Automatic voltage equalization circuit

Abstract

An automatic voltage-equalizing circuit is disclosed. The automatic voltage-equalizing circuit includes a capacitor voltage-dividing circuit, a cascade circuit, and a dynamic balance control circuit; wherein the capacitor voltage-dividing circuit includes a plurality of capacitors, the plurality of capacitors are connected in series and are configured to share the input voltage received by the capacitor voltage-dividing circuit; the cascade circuit includes a multi-stage cascade circuit unit, the multi-stage cascade circuit unit corresponds to the plurality of capacitors one by one and is electrically connected to each other; the dynamic balance control circuit is electrically connected to each cascade circuit unit of the multi-stage cascade circuit, and is configured to provide a voltage signal to each cascade circuit unit so that the input voltage is automatically equalized between the multi-stage cascade circuit units. The present invention realizes automatic voltage equalization between a plurality of capacitors by adding an auxiliary circuit in each cascade unit circuit, so that the entire output voltage is controlled by a closed-loop circuit, thereby enhancing stability.

Description

Technical Field

[0001] The invention relates to the technical field of power electronics, and in particular to an automatic voltage equalizing circuit. Background Art

[0002] In the fields of rail transportation, new energy generation, etc., the power supply voltage may be as high as several thousand volts. When converting this high voltage to other voltages, if a high-frequency switching power supply is used for direct conversion, it is necessary to select a suitable circuit topology to adapt to current semiconductor technology and take into account reliability and economy.

[0003] In the current high-voltage DC conversion topology theory, two commonly used methods are multi-level theory and cascade theory. The circuit designed using the multi-level theory is complex to control, adding clamping diodes and voltage-equalizing capacitors, and using complex control methods to suppress the dispersion of devices. The cascade circuit is relatively simple to control, and only requires the commonly used two-level circuits to be superimposed. However, in the prior art, in the cascade circuit, only two-level circuits are connected in series or in parallel, which is not enough to control the voltage of each circuit level to a better level. The main reason is that the efficiency of each two-level circuit will not be exactly the same, and the discrete parameters of the device will not be exactly the same, which brings hidden dangers to the safety of the circuit. As long as the first level that withstands high voltage fails, the entire circuit will fail. The method of using capacitors in parallel with resistors for voltage balancing is only suitable for occasions where the load is much less than the energy consumed by the parallel resistor. In applications where the actual output power is relatively large, it is limited by losses and cannot be implemented at all. Summary of the invention

[0004] The present invention provides an automatic voltage equalization circuit, the purpose of which is to realize automatic voltage equalization of cascaded multi-stage circuits when converting high voltage into other voltages through circuit design and operation, thereby meeting the reliability and economy of the circuit.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] An embodiment of the present invention provides an automatic voltage equalization circuit, including a capacitor voltage divider circuit, a cascade circuit, and a dynamic balance control circuit; wherein the capacitor voltage divider circuit includes a plurality of capacitors, the plurality of capacitors are connected in series and are configured to share the input voltage received by the capacitor voltage divider circuit; the cascade circuit includes a plurality of cascade circuit units, the plurality of cascade circuit units correspond one-to-one to the plurality of capacitors and are electrically connected to each other; the dynamic balance control circuit is electrically connected to each cascade circuit unit of the multi-stage cascade circuit, and is configured to provide a voltage signal to each cascade circuit unit so that the input voltage is automatically equalized between the plurality of cascade circuit units.

[0007] For example, the dynamic balance control circuit includes multiple auxiliary circuits, each cascade circuit unit includes a main output end for outputting the power of the cascade circuit unit at this level, and each auxiliary circuit includes an auxiliary output end, which is connected in parallel to the main output end of the cascade circuit unit adjacent to the cascade circuit unit at this level.

[0008] For example, the output voltage of each auxiliary circuit of each cascade circuit unit is equal to the output voltage of the main output terminal of the cascade circuit unit connected in parallel with the auxiliary output terminal of the auxiliary circuit.

[0009] For example, when the cascade circuit unit is a first-stage or last-stage cascade circuit unit, the auxiliary output end of the auxiliary circuit is connected in parallel to the main output end of the adjacent upper-stage or adjacent lower-stage cascade circuit unit; when the cascade circuit unit is an intermediate-stage cascade circuit unit, the intermediate-stage cascade circuit unit includes two auxiliary circuits, wherein the auxiliary output end of one auxiliary circuit is connected in parallel to the main output end of the adjacent upper-stage cascade circuit unit, and the auxiliary output end of the other auxiliary circuit is connected in parallel to the main output end of the adjacent lower-stage cascade circuit unit.

[0010] For example, each cascade circuit unit includes a transformer, which includes: a magnetic core, and a main winding and an auxiliary winding wound on the same magnetic core, wherein the main winding has the main output end for outputting the power of the cascade circuit unit of this level; the auxiliary winding constitutes the auxiliary circuit and has the auxiliary output end, which is connected in parallel to the main output end of the main winding of the cascade circuit unit adjacent to the cascade circuit unit of this level.

[0011] For example, the multi-stage cascade circuit unit includes: a first-stage cascade circuit unit, the first-stage cascade circuit unit includes a first transformer, the first transformer includes a first main winding and a first auxiliary winding; and a last-stage cascade circuit unit, the last-stage cascade circuit unit includes a second transformer, the second transformer includes a second main winding and a second auxiliary winding, wherein the auxiliary output end of the first auxiliary winding of the first transformer is connected in parallel to the main output end of the second main winding of the second transformer, so that the output voltage of the first-stage cascade circuit is transmitted to the main output end of the last cascade circuit unit.

[0012] For example, the auxiliary output end of the second auxiliary winding of the second transformer is connected in parallel to the main output end of the first main winding of the first transformer, so that the output voltage of the last stage cascade circuit is transmitted to the output end of the first stage cascade circuit unit.

[0013] For example, the multi-stage cascade circuit unit also includes: at least one intermediate cascade circuit unit located between the first-stage cascade circuit unit and the last-stage cascade circuit unit, wherein each of the intermediate cascade circuit units includes a transformer, and the transformer includes a main winding and two auxiliary windings, wherein the auxiliary output end of one auxiliary winding is connected in parallel to the main output end of the main winding of the adjacent previous-stage cascade circuit unit, and the auxiliary output end of the other auxiliary winding is connected in parallel to the main output end of the main winding of the adjacent next-stage cascade circuit unit, so that the output voltage of the intermediate-stage cascade circuit is transmitted to the output end of the adjacent previous-stage cascade circuit unit and the output end of the adjacent next-stage cascade circuit unit.

[0014] For example, the multi-stage cascade circuit unit includes at least two stages of cascade circuit units.

[0015] The beneficial effects of the present invention are: utilizing the characteristics of forcing the same current in series circuits and the same voltage in parallel circuits to make the output voltages of the power supplies of various circuits consistent, thereby automatically achieving the balance between the input side and the output side of each level of circuits. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings of the embodiments will be briefly introduced below. Obviously, the drawings in the following description only relate to some embodiments of the present invention, but are not intended to limit the present invention.

[0017] Figure 1 is a structural block diagram of an automatic voltage equalizing circuit according to an embodiment of the present invention;

[0018] Figure 2 is a schematic diagram of the principle of a dynamic balance control circuit according to an embodiment of the present invention;

[0019] Figure 3 It is a product design circuit diagram of the automatic voltage equalizing circuit of an embodiment of the present invention;

[0020] Figure 4 is a schematic diagram of the principle of a dynamic balance control circuit according to another embodiment of the present invention;

[0021] Figure 5 It is a product design circuit diagram of an automatic voltage equalizing circuit according to another embodiment of the present invention. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment 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.

[0023] In the prior art, since each cascade circuit unit is connected in parallel with a capacitor, in theory, if the three cascade circuits are exactly the same and the capacitance is exactly the same, then the voltage on each capacitor is also the same. Therefore, it is only necessary to directly connect the voltage output by the main windings of the three cascade circuit units in parallel to expand the power or directly connect them in series to increase the voltage. However, in fact, the three cascade circuits cannot be exactly the same, and the three capacitors cannot be exactly the same. The dispersion of the parasitic parameters of various components is inevitable, which will cause the natural voltage division of the capacitor to have deviations. The circuit power consumption of the three cascade circuit units is different, which will also cause the voltage division of the three capacitors to be different. Experiments have shown that if it is not controlled, the maximum voltage division may differ by 50% or more.

[0024] Figure 1 is a structural block diagram of the automatic voltage equalization circuit of an embodiment of the present invention. Figure 1 As shown, an embodiment of the present invention provides an automatic voltage equalization circuit, including an input terminal 102, a capacitor voltage divider circuit 104, a cascade circuit 106, a dynamic balance control circuit 108, a filter circuit 110 and a load 112. For example, the input terminal 102 provides a DC voltage greater than 1000V to the capacitor voltage divider circuit 104, especially a high-level DC voltage of 2000V or more. The capacitor voltage divider circuit 104 may include a plurality of capacitors, which are connected in series and configured to share the input voltage from the input terminal 102. The cascade circuit 106 includes a multi-stage cascade circuit unit J1, J2...Jn, where n is an integer greater than or equal to 2, and the multi-stage cascade circuit unit corresponds to the plurality of capacitors one by one and is electrically connected to each other, and is used to transmit the divided voltage of the corresponding capacitor to the load 112. The dynamic balance control circuit 108 is electrically connected to each of the multi-stage cascade circuit units J1, J2 ... Jn, and is configured to provide a voltage signal to each cascade circuit unit so that the input voltage is automatically balanced between the multi-stage cascade circuit units J1, J2 ... Jn. For example, the main output end of each cascade circuit unit is connected to the filter circuit 110, and after rectification and filtering, it is output to the load 112 as an output voltage.

[0025] In the automatic voltage equalization circuit of the above embodiment, by setting a dynamic balance control circuit 108, the input high voltage can be automatically equalized between the multi-stage cascade circuit units J1, J2...Jn to achieve dynamic balance, thereby ensuring the input voltage balance of each cascade circuit unit and the stability of the output voltage.

[0026] In at least some embodiments, the dynamic balance control circuit includes multiple auxiliary circuits, each cascade circuit unit includes a main output terminal for outputting the power of the cascade circuit unit at this level, and each auxiliary circuit includes an auxiliary output terminal, which is connected in parallel to the main output terminal of the cascade circuit unit adjacent to the cascade circuit unit at this level.

[0027] In at least some embodiments, the output voltage of each auxiliary circuit of each cascade circuit unit is equal to the output voltage of the main output terminal of the cascade circuit unit connected in parallel with the auxiliary output terminal of the auxiliary circuit, which is conducive to achieving automatic voltage balancing.

[0028] In at least some embodiments, when the cascade circuit unit is a first-stage or last-stage cascade circuit unit, the auxiliary output terminal of the auxiliary circuit is connected in parallel to the main output terminal of the adjacent previous-stage or next-stage cascade circuit unit;

[0029] When the cascade circuit unit is an intermediate-level cascade circuit unit, the intermediate-level cascade circuit unit includes two auxiliary circuits, wherein the auxiliary output end of one auxiliary circuit is connected in parallel to the main output end of the adjacent upper-level cascade circuit unit, and the auxiliary output end of the other auxiliary circuit is connected in parallel to the main output end of the adjacent lower-level cascade circuit unit.

[0030] In at least some embodiments, each cascade circuit unit includes a transformer, the transformer including: a magnetic core, and a main winding and an auxiliary winding wound on the same magnetic core, wherein the main winding has the main output end for outputting the power of the cascade circuit unit of the current level; the auxiliary winding constitutes the auxiliary circuit and has the auxiliary output end, the auxiliary output end is connected in parallel to the main output end of the main winding of the cascade circuit unit adjacent to the cascade circuit unit of the current level. In this way, the input voltage balance and output voltage stability of each cascade circuit unit are guaranteed.

[0031] In all embodiments of the present invention, the number of cascade circuit units can be set according to actual needs, for example, it can be two or more. The following takes three cascade circuit units as an example to further illustrate the principle of the dynamic balance control circuit of the embodiment of the present disclosure.

[0032] like Figure 2As shown, the multi-stage cascade circuit unit includes three cascade circuit units, namely a first stage cascade circuit unit J1, a second stage cascade circuit unit J2 and a third stage cascade circuit unit J3.

[0033] For example, the first-stage cascade circuit unit J1 includes a first transformer T1, and the first transformer T1 includes: a first main winding X11 and a first auxiliary winding X12. The second cascade circuit unit J2 includes a second transformer T2, and the second transformer T2 includes: a second main winding X21, a second auxiliary winding X22, and a third auxiliary winding X23. The third-stage cascade circuit unit J3 includes a third transformer T3, and the third transformer T3 includes: a third main winding X31 and a fourth auxiliary winding X32. In the embodiment of the present invention, whether the transformer has two or three windings, since the windings are all wound on a magnetic core, the power change of any winding will affect the adjustment of the power of this stage. The main output end of the first main winding X11 is used to output the power VO1 of the first-stage cascade circuit unit J1. The main output end of the second main winding X21 is used to output the power VO2 of the second cascade circuit unit J2. The main output end of the third main winding X31 is used to output the power VO3 of the third-stage cascade circuit unit J3.

[0034] In at least some embodiments, when the cascade circuit unit is the first or last stage cascade circuit unit, the auxiliary output end of the auxiliary winding is connected in parallel to the main output end of the main winding of the adjacent previous stage or next stage cascade circuit unit, so that the output voltage of the current stage cascade circuit is transmitted to the main output end of the adjacent previous stage or next stage cascade circuit unit, thereby achieving dynamic balance. Figure 2 As shown, the auxiliary output end of the first auxiliary winding X12 of the first transformer T1 is connected in parallel to the main output end of the second main winding X21 of the second transformer T2, so that the output voltage VO1 of the first-stage cascade circuit unit J1 and the output voltage VO2 of the second cascade circuit unit J2 are dynamically balanced. For another example, the auxiliary output end of the fourth auxiliary winding X32 of the third transformer T3 is connected in parallel to the main output end of the second main winding X21 of the second transformer T2, so that the output voltage VO3 of the third-stage cascade circuit unit J3 and the output voltage VO2 of the second cascade circuit unit are dynamically balanced.

[0035] In at least some embodiments, when the cascade circuit unit is an intermediate-stage cascade circuit unit, there are two auxiliary windings, wherein the auxiliary output end of one auxiliary winding is connected in parallel to the main output end of the main winding of the adjacent upper-stage cascade circuit unit, and the auxiliary output end of the other auxiliary winding is connected in parallel to the main output end of the main winding of the adjacent lower-stage cascade circuit unit, so that the output voltage of the intermediate-stage cascade circuit is transmitted to the output end of the adjacent upper-stage cascade circuit unit and the output end of the adjacent lower-stage cascade circuit unit. For example, still referring to Figure 2 The second transformer T2 includes a second auxiliary winding 22 and a third auxiliary winding 23. The auxiliary output end of the second auxiliary winding X22 is connected in parallel to the main output end of the first main winding X12 of the first transformer T1, so that the output voltage VO2 of the second-stage cascade circuit unit J2 and the output voltage VO1 of the first-stage cascade circuit unit J1 are dynamically balanced. The auxiliary output end of the third auxiliary winding X23 of the second transformer T2 is connected in parallel to the main output end of the third main winding X31 of the third transformer T3, so that the output voltage VO2 of the second-stage cascade circuit unit J2 and the output voltage VO3 of the third-stage cascade circuit unit J3 are dynamically balanced.

[0036] In the above embodiment, the output voltage of the auxiliary circuit of the first-stage cascade circuit unit J1 is the same as the output voltage of the main output terminal X21 of the second-stage cascade circuit unit J2 connected in parallel therewith, for example, both are VO2. The output voltage of one of the auxiliary circuits of the second-stage cascade circuit unit J2 is equal to the output voltage of the main output terminal X11 of the first-stage cascade circuit unit J1 connected in parallel therewith, for example, VO1; and the output voltage of another auxiliary circuit of the second-stage cascade circuit unit J2 is equal to the output voltage of the main output terminal X31 of the third-stage cascade circuit unit J3 connected in parallel therewith, for example, VO3. In order to ensure that the voltages borne by the cascade circuit units at each stage are the same, the number of turns of all windings are set to be the same, and the output voltages of each stage are equal, for example, VO1, VO2, and VO3 are equal.

[0037] Below Figure 2The working principle of the dynamic balance control circuit is described. When the auxiliary output terminal of the first-stage cascade circuit unit J1 is connected in parallel with the main output terminal of the adjacent second-stage cascade circuit unit, the input voltages borne by the two cascade circuit units can be automatically balanced. For example, when VO1 is greater than VO2, VO2 can be increased and VO1 can be reduced by the auxiliary circuit of the first-stage cascade circuit unit J1, so that VO1 and VO2 are equal to each other, thereby achieving voltage balance, and since the current of the series circuit is the same, the output power of the two-stage circuit is equal, and then the voltage borne by the input side voltage divider capacitor is also the same. Conversely, when VO1 is less than VO2, VO1 can also be increased and VO2 can be reduced by the auxiliary circuit of the second-stage cascade circuit unit J2, so that VO1 and VO2 are equal to each other, thereby achieving voltage balance. Therefore, by setting at least one auxiliary circuit in each cascade circuit unit, the voltage dynamic balance between adjacent cascade circuit units can be achieved, thereby ensuring that the voltage borne by the input voltage divider capacitor of each cascade circuit unit, the output voltage, etc. are balanced. Similarly, the two auxiliary circuits of the second-stage cascade circuit unit J2 and one auxiliary circuit of the third-stage cascade circuit unit J3 also have the above dynamic balancing function, which will not be described in detail here.

[0038] In the above embodiment, since one or two auxiliary windings are provided on the transformer of each cascade circuit unit, the auxiliary winding can transmit the output voltage of the cascade circuit unit of this level to the adjacent upper level and / or next level cascade circuit unit in parallel, so that the output voltages of any two adjacent cascade circuit units will be clamped by each other, resulting in a dynamic voltage division balance, thereby ensuring the stability of the output voltage of each cascade circuit unit. At the same time, since the current flowing through the series circuit is the same, the power consumed by each level of the cascade circuit unit is the same, thereby achieving the same input voltage of each level of the cascade circuit unit on the input side.

[0039] The embodiment of the present invention also provides a Figure 2 Product design circuit diagram of automatic voltage equalizing circuit of dynamic balance control circuit.

[0040] like Figure 3As shown, three capacitors C1, C2 and C3 constitute a capacitor voltage divider circuit. The first-stage cascade circuit unit J1 includes a MOS tube VM1, a first transformer T1, a diode VD1A and a diode VD1B. The second-stage cascade circuit unit J2 includes a MOS tube VM2, a second transformer T2, a diode VD2A, a diode VD2B, and a diode VD2C. The third-stage cascade circuit unit J3 includes a MOS tube VM3, a third transformer T3, a diode VD3A and a diode VD3C. It can be understood that any number of circuit units can be cascaded, for example, 4, 5 or more circuit units can be cascaded, and the circuit form of the intermediate-stage cascade circuit unit is the same as that of the second-stage cascade circuit unit J2. The output filter circuit includes a capacitor C4, for example, an inductor can be added to the filter circuit. Each transformer T1, T2 or T3 includes a magnetic core. This article takes the flyback topology as an example, and it can also be a forward, half-bridge, full-bridge or other topologies for automatic voltage balancing of multiple circuit units cascaded.

[0041] Theoretically, if the three cascade circuits are exactly the same, and the capacitance is exactly the same, then the voltages on C1 to C3 should also be the same. Then you only need to connect the voltages of the three windings where VD1A, VD2A, and VD3A are located in parallel to expand the power or directly connect them in series to increase the voltage. But in fact, the circuits cannot be exactly the same, the control signals G1, G2, and G3 on VM1, VM2, and VM3 will not be exactly the same, and the capacitors C1, C2, and C3 cannot be exactly the same. The dispersion of the parasitic parameters of various components is inevitable, which will cause the natural voltage division of the capacitors to have deviations. The different power consumption of the three unit circuits will also cause the voltage division of the three capacitors to be different. Experiments have shown that the difference can be 50% or more at the limit.

[0042] Above Figure 3 In the embodiment shown, the input is connected in series and the output is connected in series in parallel. Only by adding 1 to 2 diodes to each cascade unit circuit, the automatic voltage balancing between capacitors C1 to C3 can be achieved. The entire output voltage is controlled by a closed-loop circuit to maintain stability.

[0043] Below Figure 3The working principle of the automatic voltage equalization circuit is described below. When the VD2A of the second-stage cascade circuit unit J2 has a large loss in the rectification path, it is necessary to consume more energy under the same driving signal, resulting in an increase in the voltages of C1 and C3 and a low voltage of C2. As the voltages of C1 and C3 increase, the rectified voltages corresponding to the VD1A of the first-stage cascade circuit unit J1 and the VD3A of the third-stage cascade circuit unit J3 will increase. However, since an auxiliary circuit is provided in each cascade circuit unit, the voltage of VD1B of the first-stage cascade circuit unit J1 and the voltage of VD2A of the second-stage cascade circuit unit J2 can be dynamically balanced, and the voltage of VD3C of the third-stage cascade circuit unit J3 and the voltage of VD2A of the second-stage cascade circuit unit J2 can be dynamically balanced. In this way, the energy consumed on the VD2A of the second-stage cascade circuit unit J2 can be effectively supplemented until the power value corresponding to the product of its corresponding output voltage and output load current balances the imbalance caused by the excess loss of the second-stage cascade circuit unit J2. That is to say, VD1B of the first-stage cascade circuit unit J1 and VD3C of the third-stage cascade circuit unit J3 will both supply power to VD2A of the second-stage cascade circuit unit J2, automatically balancing the losses of each stage of the circuit, and clamping the output voltage of the first-stage cascade circuit unit J1 and the output voltage of the third-stage cascade circuit unit J3 to be the same as VD2A of the second-stage cascade circuit unit J2, eliminating the hidden danger of different voltages in each path. Assuming that VD2A of the second-stage cascade circuit unit J2 outputs a larger current, but since this larger current must pass through other stages in series to supply the load, the other output paths will jointly suppress this excess current, eliminating the hidden danger of unbalanced output current and balancing the input side capacitor voltage division.

[0044] The following is an example of adjusting the imbalance on the input side. Figure 3 The working principle of the automatic voltage equalization circuit is explained. Figure 3 The input voltage of the first-stage cascade unit represented by C1 is higher than the input voltage of the second-stage cascade unit represented by C2. The output voltage VO1 after transformation by the first transformer T1 is higher than the output voltage VO2 after transformation by the second transformer T2. At this time, the first transformer T1 connects VO1 in parallel to VO2 through the auxiliary winding. Since VO1 is greater than VO2, energy will be provided through the auxiliary winding first, so that the first transformer T1 consumes more energy and the second transformer T2 reduces the consumed energy. That is, the discharge of C1 increases and the discharge of C2 decreases, so the voltage provided to the first-stage cascade unit on C1 decreases, and the voltage provided to the second-stage cascade unit on C2 increases. After such adjustment, the voltage on C1 and C2 is rebalanced.

[0045] In the prior art, it is assumed that each cascade circuit unit J1 to J3 only retains its own main windings VD1A to VD3A, that is, the remaining auxiliary windings VD1B, VD2B, VD2C, and VD3C are not set, and the three-stage circuit is output in series. Then within the range of the output voltage stability value, the output voltages of the three windings are not constrained and can be freely deviated. If the loss of VD2A rectification is large, it is necessary to consume more energy under the same drive signal, resulting in an increase in the voltages of C1 and C3 and a low voltage of C2. As the voltages of C1 and C3 increase, the rectified voltages corresponding to VD1A and VD3A will increase until the corresponding total output power values ​​of each stage are stable. The advantage of the above method is that the currents of the circuits at each stage are the same (because they are connected in series), but the disadvantage is that the output voltages may differ greatly, and dynamically change between the stages, and cannot be automatically adjusted to a stable state, resulting in a large difference in the voltage pressure on the capacitors in the input side capacitor voltage divider circuit, and a large difference in the output voltage, resulting in a large requirement for the output device derating margin, which leads to a reduction in reliability and an increase in cost. This circuit also has positive feedback characteristics due to the inherent negative impedance characteristics of the switching power supply, which further deepens the imbalance. In the process of circuit balancing, due to the lack of a suppression circuit, it is very easy to form switching waveform oscillation, which can cause unstable output ripple in the least and damage the circuit in the worst.

[0046] In the automatic voltage equalization circuit of the disclosed embodiment, the characteristics of forcing the current of the series circuit to be the same and the voltage of the parallel circuit to be the same are utilized to make the output power of the power supply of each circuit consistent, thereby automatically achieving the balance between the input side and the output side of each level of the circuit.

[0047] Another embodiment of the present invention provides another circuit diagram of a dynamic balance control circuit. Figure 4 As shown, the capacitor voltage divider circuit includes three capacitors C1, C2 and C3, and the three cascade circuit units include three transformers, namely the first transformer T1, the second transformer T2 and the third transformer T3. The transformer includes a magnetic core, and a main winding and an auxiliary winding wound on the same magnetic core. Figure 4 and Figure 2 The difference is that Figure 4 The auxiliary circuit (i.e. auxiliary winding) of each cascade circuit unit is arranged in the same manner as Figure 2 The difference: Figure 4 Each auxiliary circuit is connected in parallel to the capacitor corresponding to the cascade circuit unit adjacent to the cascade circuit unit of the current level.

[0048] For example, the first stage cascade circuit unit J1 includes a first transformer T1, and the first transformer T1 includes: a first main winding X11 and a first auxiliary winding X12. The second cascade circuit unit includes a second transformer T2, and the second transformer T2 includes: a second main winding X21, a second auxiliary winding X22, and a third auxiliary winding X23. The third stage cascade circuit unit includes a third transformer T3, and the third transformer T3 includes: a third main winding X31 and a fourth auxiliary winding X32.

[0049] For example, the auxiliary winding X12 is connected in parallel to the capacitor C2 corresponding to the second-stage cascade circuit unit J2 adjacent to the first-stage cascade circuit unit J1 as an auxiliary circuit of the first-stage cascade circuit unit J1, so that the voltage of the capacitor C2 and the input voltage VC1 of the first-stage cascade circuit unit J1 are dynamically balanced. The auxiliary winding X22 is connected in parallel to the capacitor C1 corresponding to the first-stage cascade circuit unit J1 adjacent to the second-stage cascade circuit unit J2 as an auxiliary circuit of the second-stage cascade circuit unit J2, so that the voltage of the capacitor C1 and the input voltage VC2 of the second-stage cascade circuit unit J2 are dynamically balanced; at the same time, since the second transformer T2 of the second-stage cascade circuit unit J2 also includes an auxiliary winding X23, the auxiliary winding X23 is also connected in parallel to the capacitor C3 corresponding to the third-stage cascade circuit unit J3 adjacent to the second-stage cascade circuit unit J2 as an auxiliary circuit of the second-stage cascade circuit unit J2, so that the voltage of the capacitor C3 and the input voltage VC2 of the second-stage cascade circuit unit J2 are dynamically balanced. The auxiliary winding X32 serves as an auxiliary circuit of the third-stage cascade circuit unit J3 and is connected in parallel to the capacitor C2 corresponding to the second-stage cascade circuit unit J2 adjacent to the third-stage cascade circuit unit J3, so that a dynamic balance is achieved between the voltage of the capacitor C2 and the input voltage VC3 of the third-stage cascade circuit unit J3.

[0050] In the above embodiment, since one or two auxiliary windings are provided on the transformer of each cascade circuit unit, the auxiliary winding can transmit the input voltage of the cascade circuit unit of this stage to the adjacent upper and / or lower cascade circuit units in parallel. In this way, the input voltages of any two adjacent cascade circuit units will be clamped by each other, resulting in a dynamic voltage division balance, thereby ensuring the stability of the input voltage of each cascade circuit unit.

[0051] The embodiment of the present invention also provides a Figure 4 Product design circuit diagram of automatic voltage equalizing circuit of dynamic balance control circuit.

[0052] like Figure 5As shown, three capacitors C1, C2 and C3 form a capacitor voltage divider circuit. The first-stage cascade circuit unit J1 includes a MOS tube VM1, a first transformer T1, a diode VD1A and a diode VD1B. The second-stage cascade circuit unit J2 includes a MOS tube VM2, a second transformer T2, a diode VD2A, a diode VD2B, and a diode VD2C. The third-stage cascade circuit unit J3 includes a MOS tube VM3, a third transformer T3, a diode VD3A and a diode VD3C.

[0053] Above Figure 5 In the embodiment, the input is connected in parallel and the output is connected in series. Only 1 to 2 diodes are added to each cascade unit circuit to achieve automatic voltage balancing between capacitors C1 to C3. The entire output voltage is controlled by a closed-loop circuit to maintain stability.

[0054] Below Figure 5 The working principle of the automatic voltage equalization circuit is explained below. When the loss of the second-stage cascade circuit unit J2 is large, more energy needs to be consumed under the same driving signal, resulting in an increase in the voltages of C1 and C3 and a low voltage of C2. As the voltages of C1 and C3 increase, the rectified voltages corresponding to VD1B of the first-stage cascade circuit unit J1 and VD3C of the third-stage cascade circuit unit J3 will increase. The voltages output by VD1B and VD3C are connected in parallel to C2 to compensate for the extra energy consumed by C2, while increasing the energy output of the circuit unit in which they are located, so that the voltages of C2, C1, and C3 can be dynamically balanced. In other words, VD1B of the first-stage cascade circuit unit J1 and VD3C of the third-stage cascade circuit unit J3 will both supply power to C2 of the second-stage cascade circuit unit J2 at the same time, automatically balancing the losses of each stage of the circuit.

[0055] In the automatic voltage equalization circuit of the above embodiment of the present disclosure, the characteristics of forcing the current of the series circuit to be the same and the voltage of the parallel circuit to be the same are utilized to make the output power of the power supply of each circuit consistent, thereby automatically achieving the balance between the input side and the output side of each level of the circuit.

[0056] The features, structures or characteristics described in the above embodiments may be combined in one or more embodiments in any other suitable manner. In the above description, some specific details, such as circuits, devices, etc., are provided to provide a comprehensive understanding of the embodiments of the present invention. However, it should be understood by those skilled in the art that the present invention can be implemented without the above one or more specific details, or can also be implemented using other components, materials, methods, etc. In other examples, well-known structures, materials or operations are not shown or described in detail to avoid blurring various aspects of the present invention.

Claims

1. An automatic voltage equalization circuit, characterized in that: It includes an input terminal, a capacitor voltage divider circuit, a cascade circuit, and a dynamic balance control circuit; wherein, The input end provides an input voltage to the capacitive voltage divider circuit, and the input voltage is a DC voltage greater than 1000V; The capacitive voltage divider circuit comprises a plurality of capacitors, the plurality of capacitors being connected in series with each other and configured to share an input voltage received by the capacitive voltage divider circuit; The cascade circuit comprises a plurality of cascade circuit units, wherein the plurality of cascade circuit units correspond to the plurality of capacitors one by one and are electrically connected to each other; The dynamic balance control circuit is electrically connected to each cascade circuit unit of the multi-stage cascade circuit and is configured to provide a voltage signal to each cascade circuit unit so that the input voltage is automatically balanced among the multi-stage cascade circuit units. The dynamic balance control circuit includes a plurality of auxiliary circuits, each cascade circuit unit includes a main output terminal for outputting the power of the cascade circuit unit at the same level, and each auxiliary circuit includes an auxiliary output terminal, which is connected in parallel to the main output terminal of the cascade circuit unit adjacent to the cascade circuit unit at the same level. Wherein, when the cascade circuit unit is the first or last stage cascade circuit unit, the auxiliary output end of the auxiliary circuit is connected in parallel to the main output end of the adjacent previous stage or next stage cascade circuit unit, so that the input voltages borne by the two cascade circuit units can be automatically balanced; When the cascade circuit unit is an intermediate-level cascade circuit unit, the intermediate-level cascade circuit unit includes two auxiliary circuits, wherein the auxiliary output end of one auxiliary circuit is connected in parallel to the main output end of the adjacent upper-level cascade circuit unit, and the auxiliary output end of the other auxiliary circuit is connected in parallel to the main output end of the adjacent lower-level cascade circuit unit.

2. The automatic voltage equalization circuit according to claim 1, characterized in that: The output voltage of each auxiliary circuit of each cascade circuit unit is equal to the output voltage of the main output terminal of the cascade circuit unit connected in parallel with the auxiliary output terminal of the auxiliary circuit.

3. The automatic voltage equalization circuit according to claim 2, characterized in that: Each cascade circuit unit includes a transformer, wherein the transformer includes: A magnetic core, and a main winding and an auxiliary winding wound on the same magnetic core, wherein: The main winding has the main output end for outputting the power of the cascade circuit unit of the current stage; the auxiliary winding constitutes the auxiliary circuit and has the auxiliary output end, which is connected in parallel to the main output end of the main winding of the cascade circuit unit adjacent to the cascade circuit unit of the current stage.

4. The automatic voltage equalization circuit according to claim 3, characterized in that: The multi-stage cascade circuit unit comprises: a first-stage cascade circuit unit, the first-stage cascade circuit unit comprising a first transformer, the first transformer comprising a first main winding and a first auxiliary winding; and a last stage cascade circuit unit, the last stage cascade circuit unit comprising a second transformer, the second transformer comprising a second main winding and a second auxiliary winding, The auxiliary output end of the first auxiliary winding of the first transformer is connected in parallel to the main output end of the second main winding of the second transformer, so that the output voltage of the first stage cascade circuit is transmitted to the main output end of the last cascade circuit unit.

5. The automatic voltage equalization circuit according to claim 4, characterized in that: The auxiliary output end of the second auxiliary winding of the second transformer is connected in parallel to the main output end of the first main winding of the first transformer, so that the output voltage of the last stage cascade circuit is transmitted to the output end of the first stage cascade circuit unit.

6. The automatic voltage equalizing circuit according to claim 4 or 5, characterized in that: The multi-stage cascade circuit unit further comprises: at least one intermediate stage cascade circuit unit located between the first stage cascade circuit unit and the last stage cascade circuit unit, Each of the intermediate-level cascade circuit units includes a transformer, which includes a main winding and two auxiliary windings, wherein the auxiliary output end of one auxiliary winding is connected in parallel to the main output end of the main winding of the adjacent upper-level cascade circuit unit, and the auxiliary output end of the other auxiliary winding is connected in parallel to the main output end of the main winding of the adjacent lower-level cascade circuit unit, so that the output voltage of the intermediate-level cascade circuit is transmitted to the output end of the adjacent upper-level cascade circuit unit and the output end of the adjacent lower-level cascade circuit unit.

7. The automatic voltage equalization circuit according to claim 1, characterized in that: The multi-stage cascade circuit unit includes at least two stages of cascade circuit units.

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