Automatic voltage balancing auxiliary power supply system

Abstract

The utility model provides an automatic voltage balancing auxiliary power supply system, and belongs to the technical field of auxiliary power supplies. According to the automatic voltage balancing auxiliary power supply system, the first end of a first capacitor E21 is connected with a first direct current bus, the first end of a second capacitor E22 is connected with a second direct current bus, and the second end of the first capacitor E21 is connected with the second end of the second capacitor E22; the first input end of the transformer T5 is connected with the first end of the first capacitor E21, the second input end of the transformer T5 is connected with the first end of the switching tube Q6, and the second end of the switching tube Q6 is connected with the second end of the first capacitor E21; the third input end of the transformer T5 is connected with the second end of the second capacitor E22, the fourth input end of the transformer T5 is connected with the first end of the switching tube Q7, and the second end of the switching tube Q7 is connected with the first end of the second capacitor E22; the first output end of the transformer T5 is used for outputting power supply voltage. The problem that a traditional automatic constant-voltage auxiliary power supply system is low in efficiency can be solved.

Description

Technical Field

[0001] The present disclosure relates to the technical field of auxiliary power supplies, and in particular to an automatic voltage-balanced auxiliary power supply system. Background Art

[0002] In power electronics systems, especially those dealing with high-voltage inputs such as three-phase AC, the rectified DC bus voltage fluctuates widely, often requiring the use of series electrolytic capacitors for filtering and energy storage. However, due to differences in the internal resistance of electrolytic capacitors, series use often results in uneven voltage distribution, causing some capacitors to be subjected to excessive voltage, impacting system stability and capacitor life. Traditionally, parallel balancing resistors have been used to balance the capacitor voltages, but this approach increases system energy loss and reduces overall efficiency. Utility Model Content

[0003] The embodiments of the present disclosure provide an automatic constant voltage auxiliary power supply system to solve the problem of low efficiency of traditional automatic constant voltage auxiliary power supply systems.

[0004] The embodiment of the present disclosure provides an automatic voltage-balanced auxiliary power supply system, comprising: a driving module, a first capacitor E21, a second capacitor E22, a transformer T5, a switch tube Q6, and a switch tube Q7;

[0005] A first end of the first capacitor E21 is connected to the first DC bus, a first end of the second capacitor E22 is connected to the second DC bus, and a second end of the first capacitor E21 is connected to the second end of the second capacitor E22;

[0006] The first input end of the transformer T5 is connected to the first end of the first capacitor E21, the second input end of the transformer T5 is connected to the first end of the switch tube Q6, the second end of the switch tube Q6 is connected to the second end of the first capacitor E21, and the control end of the switch tube Q6 is connected to the driving module;

[0007] The third input terminal of the transformer T5 is connected to the second terminal of the second capacitor E22, the fourth input terminal of the transformer T5 is connected to the first terminal of the switch tube Q7, the second terminal of the switch tube Q7 is connected to the first terminal of the second capacitor E22, and the control terminal of the switch tube Q7 is connected to the driving module;

[0008] The first output terminal of the transformer T5 is used to output a power supply voltage, and the second output terminal of the transformer T5 is grounded.

[0009] In an exemplary embodiment of the present disclosure, it further includes:

[0010] Resistor R179 and resistor R199;

[0011] A first end of the resistor R179 is connected to the second end of the switch tube Q6, and a second end of the resistor R179 is connected to the second end of the first capacitor E21;

[0012] A first end of the resistor R199 is connected to the second end of the switch tube Q7 , and a second end of the resistor R199 is connected to the first end of the second capacitor E22 .

[0013] In an exemplary embodiment of the present disclosure, it further includes:

[0014] Diode D50 and capacitor C118;

[0015] The anode of the diode D50 is connected to the first output terminal of the transformer T5 , the cathode of the diode D50 is grounded via the capacitor C118 , and the cathode of the diode D50 is used to output a power supply voltage.

[0016] In an exemplary embodiment of the present disclosure, it further includes:

[0017] Capacitor C176, resistor R176, diode D54, capacitor C178, resistor R177, and diode D53;

[0018] A first end of the capacitor C176 is connected to the first input end of the transformer T5, a second end of the capacitor C176 is connected to the cathode of the diode D54, the resistor R176 is connected in parallel to the capacitor C176, and the anode of the diode D54 is connected to the second input end of the transformer T5;

[0019] The first end of the capacitor C178 is connected to the third input end of the transformer T5, the second end of the capacitor C178 is connected to the cathode of the diode D53, the resistor R177 is connected in parallel with the capacitor C178, and the anode of the diode D53 is connected to the fourth input end of the transformer T5.

[0020] In an exemplary embodiment of the present disclosure, it further includes: a rectifier module;

[0021] The first input end of the rectifier module is used to connect U-phase electricity, the second input end of the rectifier module is used to connect V-phase electricity, the third input end of the rectifier module is used to connect W-phase electricity, the first output end of the rectifier module serves as a first DC bus, and the second output end of the rectifier module serves as a second DC bus.

[0022] The beneficial effects of an automatic voltage-balancing auxiliary power supply system provided by the embodiment of the present disclosure are as follows: the embodiment of the present disclosure realizes automatic balanced control of the voltage of the series electrolytic capacitors through the flyback topology structure composed of the driving module, the switch tube and the transformer. The embodiment of the present disclosure does not require a traditional balancing resistor, avoids the additional loss caused by the resistor, and improves the overall efficiency. By accurately adjusting the PWM control signal of the switch tube, it can respond to the capacitor voltage difference in real time, dynamically adjust the output voltage, ensure the voltage balance between the capacitors, and extend the service life of the capacitors. This not only solves the problem of uneven voltage of capacitors in series under high voltage, but also reduces the voltage resistance requirements of the series capacitors, thereby improving the reliability and economy of the auxiliary power supply system. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0024] Figure 1 is a circuit diagram of an automatic voltage-controlled auxiliary power supply system provided by an embodiment of the present disclosure;

[0025] Figure 2 is a circuit diagram of a traditional automatic constant voltage auxiliary power supply system provided by an embodiment of the present disclosure. DETAILED DESCRIPTION

[0026] To help those skilled in the art better understand this solution, the following will clearly describe the technical solutions in the embodiments of this solution in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of this solution, not all of it. Based on the embodiments of this solution, all other embodiments obtained by those skilled in the art without creative work should fall within the scope of protection of this solution.

[0027] Throughout the specification, claims, and accompanying figures of this solution, the term "including" and any variations thereof mean "including, but not limited to," and are intended to cover non-exclusive inclusions and are not limited to the examples listed herein. Furthermore, the terms "first" and "second," etc., are used to distinguish between different objects, not to describe a specific order.

[0028] The following describes the implementation of the present disclosure in detail with reference to the accompanying drawings:

[0029] Figure 1 This is a schematic diagram of the structure of an automatic voltage-controlled auxiliary power supply system provided by an embodiment of the present disclosure. Figure 1The automatic voltage-balancing auxiliary power supply system includes: a driving module, a first capacitor E21, a second capacitor E22, a transformer T5, a switch tube Q6 and a switch tube Q7; the first end of the first capacitor E21 is connected to the first DC bus, the first end of the second capacitor E22 is connected to the second DC bus, and the second end of the first capacitor E21 is connected to the second end of the second capacitor E22; the first input end of the transformer T5 is connected to the first end of the first capacitor E21, the second input end of the transformer T5 is connected to the first end of the switch tube Q6, the second end of the switch tube Q6 is connected to the second end of the first capacitor E21, and the control end of the switch tube Q6 is connected to the driving module; the third input end of the transformer T5 is connected to the second end of the second capacitor E22, the fourth input end of the transformer T5 is connected to the first end of the switch tube Q7, the second end of the switch tube Q7 is connected to the first end of the second capacitor E22, and the control end of the switch tube Q7 is connected to the driving module; the first output end of the transformer T5 is used to output the power supply voltage, and the second output end of the transformer T5 is grounded.

[0030] With three-phase AC input, when the input voltage is AC380V ± 20%, the rectified output voltage is 429-644VDC. To transmit power to subsequent circuits, electrolytic capacitors are connected to the rectified DC bus for filtering and energy storage. Conventional electrolytic capacitors have a maximum withstand voltage of 450V, so two filter and energy storage capacitors must be connected in series.

[0031] like Figure 2 As shown, when a first capacitor E21 and a second capacitor E22 are connected in series, the voltages across the first and second capacitors E21 and E22 are not consistent due to the difference in their internal resistances. The capacitor with the larger internal resistance has a higher voltage. To address this issue, a conventional approach is to add balancing resistors to both capacitors. These resistors are connected in parallel with the internal resistances to balance the capacitor impedances. However, since the voltages across the capacitors are relatively high, a too large balancing resistor will not achieve the desired balance. A too small resistor will increase resistance losses, reducing efficiency.

[0032] In order to solve the capacitor bias problem without increasing losses, this embodiment uses an auxiliary power system to automatically balance the voltages of the series capacitors.

[0033] like Figure 1 As shown, in this embodiment, transformer T5, switch Q6, and switch Q7 form a flyback topology. Transformer T5 outputs voltage using pulse-width modulation (PWM). The driver module is configured to output a PWM control signal. When the output voltage is higher than a set value, the drive pulse widths of switches Q6 and Q7 are reduced. When the output voltage is lower than the set value, the drive pulse widths of switches Q6 and Q7 are increased. Voltage stabilization is achieved through multiple PWM modulation cycles within a cycle.

[0034] In this embodiment, the first input terminal of the transformer T5 and the second input terminal of the transformer T5 constitute a first primary winding (T17C), the third input terminal of the transformer T5 and the fourth input terminal of the transformer T5 constitute a second primary winding (T17B), and the first output terminal of the transformer T5 and the second output terminal of the transformer T5 constitute a secondary winding (T17A).

[0035] The two primary windings of transformer T5 are connected in parallel, and their component parameters are identical. Assuming the ratio of the two primary windings T17C, T17B, and T17A of transformer T5 are both n, and at a certain moment, the driving time of the switch tubes Q6 and Q7 is 0.4T, then the voltages on the secondary winding T17A corresponding to the primary windings T17C and T17B are Ve21*0.4T / n / (1-0.4T)=T17C1 and Ve22*0.4T / n / (1-0.4T)=T17B1, respectively.

[0036] Where Ve21 is the voltage across the first capacitor E21, and Ve22 is the voltage across the second capacitor E22. If the voltage Ve21 across the first capacitor E21 is higher than the voltage Ve22 across the second capacitor E22, then T17C1 > T17B1. Due to the parallel connection, the output power is provided by the first capacitor E21, reducing the voltage across the first capacitor E21. The reverse is also true, achieving dynamic balance between the upper and lower capacitor voltages, further reducing the withstand voltage of the series capacitors and lowering costs.

[0037] From the above, it can be concluded that this embodiment realizes automatic balanced control of the voltage of the series electrolytic capacitors through the flyback topology composed of the drive module, the switch tube and the transformer. This embodiment does not require a traditional balancing resistor, avoids the additional loss caused by the resistor, and improves the overall efficiency. By accurately adjusting the PWM control signal of the switch tube, it is possible to respond to the capacitor voltage difference in real time, dynamically adjust the output voltage, ensure the voltage balance between the capacitors, and extend the service life of the capacitors. This not only solves the problem of uneven voltage in series capacitors under high voltage, but also reduces the withstand voltage requirement of the series capacitors, thereby improving the reliability and economy of the auxiliary power supply system.

[0038] In one embodiment of the present disclosure, the system further includes: a resistor R179 and a resistor R199; a first end of the resistor R179 is connected to the second end of the switch tube Q6, and a second end of the resistor R179 is connected to the second end of the first capacitor E21; a first end of the resistor R199 is connected to the second end of the switch tube Q7, and a second end of the resistor R199 is connected to the first end of the second capacitor E22.

[0039] In this embodiment, when switch Q6 or Q7 is turned on or off, significant current fluctuations may occur in the circuit. Resistors R179 and R199 can provide a certain current-limiting effect, limiting sudden current fluctuations and preventing excessive current from damaging the switch, capacitor, and other components. Especially when switch Q6 or Q7 is turned on, the DC bus voltage may be instantly applied to the primary winding of the transformer. Without current-limiting measures, a large inrush current may be generated.

[0040] Therefore, the resistor R179 and the resistor R199 can play the role of current limiting, stabilizing the working state and assisting in voltage balancing in the circuit.

[0041] In one embodiment of the present disclosure, it further includes: a diode D50 and a capacitor C118; the anode of the diode D50 is connected to the first output terminal of the transformer T5, the cathode of the diode D50 is grounded through the capacitor C118, and the cathode of the diode D50 is used to output the supply voltage.

[0042] In this embodiment, the automatic constant-voltage auxiliary power supply system converts a three-phase AC voltage signal into a low-voltage DC signal, which serves as an auxiliary power source for the power consumption system. During normal operation, the output of transformer T5 is an AC signal. To meet the DC power supply requirements, the AC signal output by transformer T5 must be converted to a DC signal.

[0043] When transformer T5's secondary winding outputs AC power, diode D50 acts as a rectifier. It allows current to flow only from the transformer's output to capacitor C118 and the load, preventing reverse current flow. This converts the transformer's AC output voltage into a unidirectional, pulsating DC voltage, providing a stable power source for subsequent circuits.

[0044] Capacitor C118 acts as a filter. The pulsating DC voltage rectified by diode D50 contains significant ripple. The capacitor smoothes the output voltage and reduces ripple through its charge and discharge process. When the output voltage increases, the capacitor charges; when the output voltage decreases, the capacitor discharges, making the output voltage more stable.

[0045] From the above, it can be concluded that the diode D50 and the capacitor C118 play the role of rectification and filtering energy storage in the circuit, and together provide a stable power supply voltage for the subsequent circuits.

[0046] In one embodiment of the present disclosure, the system further includes: a capacitor C176, a resistor R176, a diode D54, a capacitor C178, a resistor R177 and a diode D53; a first end of the capacitor C176 is connected to the first input end of the transformer T5, a second end of the capacitor C176 is connected to the cathode of the diode D54, the resistor R176 and the capacitor C176 are connected in parallel, and the anode of the diode D54 is connected to the second input end of the transformer T5; a first end of the capacitor C178 is connected to the third input end of the transformer T5, a second end of the capacitor C178 is connected to the cathode of the diode D53, the resistor R177 and the capacitor C178 are connected in parallel, and the anode of the diode D53 is connected to the fourth input end of the transformer T5.

[0047] In this embodiment, capacitor C176, resistor R176, and diode D54, as well as capacitor C178, resistor R177, and diode D53, respectively, constitute a protection circuit. Capacitors C176 and C178 can absorb the spike voltage generated by the primary winding of the transformer when the switch tube is turned on and off. When the state of the switch tube changes, the current in the primary winding of the transformer will change rapidly, thereby generating a high induced electromotive force, which may form a spike voltage. The capacitor can absorb these spike voltages by charging, protecting the switch tube and the transformer. Diodes D54 and D53 can act as a clamp. When the induced electromotive force in the primary winding of the transformer reverses, the diodes can turn on, clamping the voltage to a specific level, preventing excessive voltage from damaging components.

[0048] From the above, it can be concluded that capacitor C176, resistor R176, diode D54, capacitor C178, resistor R177 and diode D53 play a protective role in the circuit, and together improve the stability and reliability of the automatic constant voltage auxiliary power supply system.

[0049] In one embodiment of the present disclosure, it also includes: a rectifier module; the first input end of the rectifier module is used to connect to U-phase electricity, the second input end of the rectifier module is used to connect to V-phase electricity, the third input end of the rectifier module is used to connect to W-phase electricity, the first output end of the rectifier module serves as a first DC bus, and the second output end of the rectifier module serves as a second DC bus.

[0050] In this embodiment, the function of the rectifier module is to convert three-phase AC power (U phase, V phase, W phase) into DC power. After the three-phase AC power is input to the rectifier module, it undergoes a rectification process (such as Figure 2 As shown, diodes D1, D2, D3, D4, D5, and D6 form a three-phase bridge rectifier circuit (converting the current to a smooth DC output). In this embodiment, the first and second output terminals of the rectifier module serve as the first and second DC busbars, respectively, providing a stable DC power supply for subsequent circuits.

[0051] The above embodiments are only used to illustrate the technical solutions of the present disclosure, rather than to limit them. Although the present disclosure has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present disclosure.

Claims

1. An automatic voltage-controlled auxiliary power supply system, characterized in that: include: Driving module, first capacitor E21, second capacitor E22, transformer T5, switch tube Q6 and switch tube Q7; A first end of the first capacitor E21 is connected to the first DC bus, a first end of the second capacitor E22 is connected to the second DC bus, and a second end of the first capacitor E21 is connected to the second end of the second capacitor E22; The first input end of the transformer T5 is connected to the first end of the first capacitor E21, the second input end of the transformer T5 is connected to the first end of the switch tube Q6, the second end of the switch tube Q6 is connected to the second end of the first capacitor E21, and the control end of the switch tube Q6 is connected to the driving module; The third input terminal of the transformer T5 is connected to the second terminal of the second capacitor E22, the fourth input terminal of the transformer T5 is connected to the first terminal of the switch tube Q7, the second terminal of the switch tube Q7 is connected to the first terminal of the second capacitor E22, and the control terminal of the switch tube Q7 is connected to the driving module; The first output terminal of the transformer T5 is used to output a power supply voltage, and the second output terminal of the transformer T5 is grounded.

2. The automatic voltage-controlled auxiliary power supply system according to claim 1, wherein: Also includes: Resistor R179 and resistor R199; A first end of the resistor R179 is connected to the second end of the switch tube Q6, and a second end of the resistor R179 is connected to the second end of the first capacitor E21; A first end of the resistor R199 is connected to the second end of the switch tube Q7 , and a second end of the resistor R199 is connected to the first end of the second capacitor E22 .

3. The automatic voltage-controlled auxiliary power supply system according to claim 1, wherein: Also includes: Diode D50 and capacitor C118; The anode of the diode D50 is connected to the first output terminal of the transformer T5 , the cathode of the diode D50 is grounded via the capacitor C118 , and the cathode of the diode D50 is used to output a power supply voltage.

4. The automatic voltage-controlled auxiliary power supply system according to claim 1, wherein: Also includes: Capacitor C176, resistor R176, diode D54, capacitor C178, resistor R177, and diode D53; A first end of the capacitor C176 is connected to the first input end of the transformer T5, a second end of the capacitor C176 is connected to the cathode of the diode D54, the resistor R176 is connected in parallel to the capacitor C176, and the anode of the diode D54 is connected to the second input end of the transformer T5; The first end of the capacitor C178 is connected to the third input end of the transformer T5, the second end of the capacitor C178 is connected to the cathode of the diode D53, the resistor R177 is connected in parallel with the capacitor C178, and the anode of the diode D53 is connected to the fourth input end of the transformer T5.

5. The automatic voltage-controlled auxiliary power supply system according to claim 1, wherein: Also includes: Rectifier module; The first input end of the rectifier module is used to connect U-phase electricity, the second input end of the rectifier module is used to connect V-phase electricity, the third input end of the rectifier module is used to connect W-phase electricity, the first output end of the rectifier module serves as a first DC bus, and the second output end of the rectifier module serves as a second DC bus.

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