Main and auxiliary integrated power supply system

Abstract

The utility model discloses a main and auxiliary integrated power supply system, and specifically relates to the technical field of power supply systems, the main and auxiliary integrated power supply system comprises a main power supply, the main power supply is connected with an auxiliary power supply, the main power supply and the auxiliary power supply are both electrically connected with a master control cabinet, the output end of the master control cabinet is connected with a load through a reversing cabinet, and the auxiliary power supply comprises a circuit breaker. A power grid is connected with a soft start circuit through a circuit breaker, the soft start circuit is connected with an isolation transformer T1 in series, the isolation transformer T1 is connected with an ACDC optimization circuit, and the ACDC optimization circuit is connected with a DCDC staggered step-down chopper circuit. In order to meet the requirements of corresponding speed and output current regulation precision, a high-precision compensation auxiliary power supply is added to an original system. A PWM rectifier principle is adopted, and a power device adopts an IGBT single tube. According to the PWM rectifier, a traditional phase-controlled rectifier is comprehensively improved. The key improvement is that a full-control power switch is used for replacing a half-control power switch, and PWM chopped-control rectification is used for replacing phase-control rectification.

Description

Technical Field

[0001] This utility model relates to the field of power supply system technology, specifically a main and auxiliary power supply system. Background Technology

[0002] The existing power supply system has a short lifespan, especially in coastal areas where salt spray and humidity are severe, creating harsh environments that cause much more serious corrosion and aging of components than in normal conditions. Currently, the control section, particularly capacitive components, is aging significantly, affecting the accuracy and stability of the power supply system. The original main power circuit used a fully controlled three-phase bridge rectifier circuit with thyristors as power devices. While thyristors are widely used in traditional phase-controlled rectifiers and have a long history of application, mature technology, and widespread use, the following problems still exist:

[0003] (1) Low sampling accuracy leads to large output current error.

[0004] (2) Decreased accuracy due to device aging

[0005] (3) The dynamic response is relatively slow during closed-loop control. Utility Model Content

[0006] The purpose of this invention is to provide a main and auxiliary power supply system to solve the problems raised in the prior art.

[0007] To achieve the above objectives, this utility model provides the following technical solution:

[0008] The main and auxiliary power supply system includes a main power supply connected to an auxiliary power supply. Both the main power supply and the auxiliary power supply are electrically connected to a main control cabinet. The output of the main control cabinet is connected to the load through a reversing cabinet. The auxiliary power supply includes a circuit breaker. The power grid is connected to a soft starter circuit through the circuit breaker. The soft starter circuit is connected in series with an isolation transformer T1. The isolation transformer T1 is connected to an AC / CDC optimization circuit. The AC / CDC optimization circuit is connected to a DC / CDC alternating step-down chopper circuit.

[0009] In a preferred embodiment, the soft start circuit includes AC contactors KM1 and KM2 connected in parallel, and the AC contactors are connected in parallel with a resistor R.

[0010] In a preferred embodiment, the three-phase output of the power grid is connected to the input terminal of circuit breaker QF, the output terminal of circuit breaker QF is connected to the input terminals of AC contactor KM1 and AC contactor KM2 respectively, the three-phase output terminals of AC contactor KM2 are respectively connected to resistors R1, R2 and R3, and the output terminals of resistors R1, R2 and R3 are connected to the three output terminals of AC contactor KM1 and then connected to the input terminal of isolation transformer T1.

[0011] In a preferred embodiment, the DC-DC interleaved buck chopper circuit includes a fuse FU1 and a resistor R2 connected to capacitor C2. The AC-DC optimization circuit includes a capacitor C1 and an inductor L connected to isolation transformer T1. The three-phase output terminals of the isolation transformer T1 are respectively connected to the three input terminals of the inductor L. The three output terminals of the inductor L are respectively connected to three current sensors LEM. The three current sensors LEM are respectively connected to two IGBT single transistors connected in series. The three sets of IGBT single transistors connected in series are connected in parallel and then connected to capacitor C2.

[0012] In a preferred embodiment, resistor R2 is connected in parallel with capacitor C3, and capacitor C3 is connected in parallel with four sets of IGBT single transistors arranged in series. The four sets of IGBT single transistors are connected in parallel to four inductors L, and one end of each inductor L is connected in series with a current sensor LEM. The current sensor LEM is connected to capacitor C4.

[0013] In a preferred embodiment, the DC-DC interleaved buck chopper circuit adopts an interleaved parallel PWM generation method, and the four BUCK circuits have a PWM phase difference of 90 degrees.

[0014] Compared with the prior art, the beneficial effects of this utility model are:

[0015] 1. The main and auxiliary power supply system described in this utility model adds a high-precision compensation auxiliary power supply to the original system to meet the requirements of corresponding speed and output current regulation accuracy. The basic principle adopts the PWM rectifier principle, and the power device uses a single IGBT transistor. The PWM rectifier has comprehensively improved upon the traditional phase-controlled rectifier. Its key improvement lies in replacing the semi-controlled power switch (thyristor) with a fully controlled power switch (IGBT), and replacing phase-controlled rectification with PWM chopper rectification.

[0016] 2. The integrated main and auxiliary power supply system described in this utility model not only enables bidirectional energy transmission through its PWM rectifier but also achieves sinusoidal grid-side current operation, allowing it to operate at unity power factor. This overcomes the impact of traditional thyristor phase-controlled rectification on the power grid and electrical equipment. Furthermore, through appropriate control strategies, the AC-side current and power factor of the PWM rectifier can be controlled, enabling not only unity power factor rectification and inversion but also four-quadrant operation of the PWM rectifier. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of this utility model;

[0018] Figure 2 This is a circuit diagram for the modification of the main power supply system of this utility model;

[0019] Figure 3 This is a schematic diagram of the main electrical topology of the auxiliary power supply of this utility model;

[0020] Figure 4 This is a circuit diagram of the soft start circuit and isolation transformer of this utility model;

[0021] Figure 5 This is a circuit diagram of the isolation transformer and the optimized ACDC circuit of this utility model;

[0022] Figure 6 This is the circuit diagram of the DC-DC interleaved buck chopper circuit of this utility model. Detailed Implementation

[0023] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0024] Example: Please refer to Figures 1-6 This utility model provides a main and auxiliary power supply system, the technical solution of which is as follows:

[0025] like Figures 1-3 As shown, the main and auxiliary power supply system includes a main power supply connected to an auxiliary power supply. Both the main and auxiliary power supplies are electrically connected to the main control cabinet. The output of the main control cabinet is connected to the load through a commutator cabinet. The auxiliary power supply includes a circuit breaker, and the power grid is connected to a soft starter circuit through the circuit breaker. The soft starter circuit is connected in series with an isolation transformer T1. The isolation transformer T1 is connected to an AC / CDC optimization circuit, which is connected to a DC / CDC interleaved step-down chopper circuit. Digital circuit control is adopted. This high-precision auxiliary power supply determines the demagnetization parameters with the main power supply through communication, synchronizes with the main power supply through operation / pulse switching signals, and samples the output demagnetization current through a high-precision Hall element to achieve accurate compensation of the output current.

[0026] In a preferred embodiment, the soft start circuit includes AC contactors KM1 and KM2 connected in parallel, and the AC contactors are connected in parallel with a resistor R.

[0027] Specific examples Figure 3As shown, at the instant the input circuit closes, due to the capacitive load characteristics of the filter capacitor, it is momentarily equivalent to a short circuit, resulting in a large current surge through the capacitor. This affects system safety and capacitor lifespan, especially for high-power switching power supplies that use large-capacity filter capacitors at the input, leading to a significant inrush current. A large inrush current amplitude at the moment of power-on may prevent the circuit breaker from closing or even burn out the contacts of the closing switch, all of which can prevent the power supply from being put into operation normally. Therefore, a soft-start circuit to prevent inrush current is installed in the input circuit. The capacitor is first charged through the soft-start resistor path. Once the capacitor voltage reaches a stable value close to the grid voltage, the main circuit is engaged, avoiding the impact of the instantaneous power-on surge on the capacitor and ensuring normal and reliable power supply operation. The mains power input is 380V±10%, 50Hz±5Hz AC, connected to the power supply after passing through the input circuit breaker QF. This avoids a large inrush current at the moment of system power-on. The input terminal first passes through the soft-start circuit; once the capacitor voltage reaches a stable value close to the grid voltage, the main circuit is engaged. After the main circuit is put into normal operation, it passes through the isolation transformer T1 to the PWM rectifier module, and outputs a stable DC bus voltage.

[0028] In a preferred embodiment, the three-phase output of the power grid is connected to the input terminal of circuit breaker QF, the output terminal of circuit breaker QF is connected to the input terminals of AC contactor KM1 and AC contactor KM2 respectively, the three-phase output terminals of AC contactor KM2 are respectively connected to resistors R1, R2 and R3, and the output terminals of resistors R1, R2 and R3 are connected to the three output terminals of AC contactor KM1 and then connected to the input terminal of isolation transformer T1.

[0029] Specific examples Figure 4 As shown, when the input power supply voltage fluctuates within the range of 380V±10%, it will affect the DCBUS voltage. To ensure the output voltage regulation requirement, the inverter's PWM duty cycle needs to meet the DC BUS voltage variation requirements. When the input power supply voltage decreases, causing the DC BUS voltage to drop, the PWM duty cycle will automatically increase to meet the output voltage stability requirement. Similarly, when the input power supply voltage increases, causing the DC BUS voltage to rise, the PWM duty cycle will automatically decrease to also meet the output voltage stability requirement. When the input power supply voltage fluctuates within the range of 380V±10%, it will affect the stability of the PCBA-level control system's operating power supply. To ensure the safety and reliability of the control system's power supply, this part adopts the company's mature DC SWITH POWER technology and is designed as a switching power supply module to provide reliable power supply protection with wide input variation for the overall power supply.

[0030] In a preferred embodiment, the ACCDC optimization circuit includes a capacitor C1 and an inductor L connected to an isolation transformer T1. The three-phase output terminals of the isolation transformer T1 are respectively connected to the three input terminals of the inductor L. The three output terminals of the inductor L are respectively connected to three current sensors LEM. The three current sensors LEM are respectively connected to two IGBT single transistors connected in series. The three sets of IGBT single transistors connected in series are connected in parallel and then connected to a capacitor C2.

[0031] Specific examples Figure 5 As shown, due to the AC-DC topology of the power supply itself, the AC-DC rectifier unit before the input stage can easily lower the power factor at the input. To ensure that the power factor at the input is not less than 0.99, it is necessary to perform calculations and adopt phase-shifted PWM controllable rectification technology, along with a matching input inductor, to ensure that the power supply's power factor (PF) is ≥0.99 under full load and that grid harmonics are kept below 5%. To ensure that the system has excellent power quality characteristics, the AC ITHD must be controlled below 5%, and the power factor must reach ≥0.99. Based on the system bus voltage requirements and inverter switching frequency, the equivalent inductance of the LC filter inductor is calculated. The transformer on the grid side adopts a star-shaped structure design, based on the cutoff frequency requirements: Where fc is the system switching frequency and Fl is the cutoff frequency of the LC filter system. EACO three-phase AC filter capacitors are selected for the LC filter.

[0032] In a preferred embodiment, the DC-DC interleaved buck chopper circuit includes a fuse FU1 connected to capacitor C2 and a resistor R2. Resistor R2 is connected in parallel with capacitor C3. Four IGBT transistors connected in series are connected in parallel with capacitor C3. The four IGBT transistors are then connected in parallel to four inductors L. Each inductor L has a current sensor LEM connected in series at one end, and the current sensor LEM is connected to capacitor C4. The DC-DC interleaved buck chopper circuit employs an interleaved parallel PWM generation method, with the four BUCK circuit PWM phases differing by 90 degrees.

[0033] Specific examples Figure 6As shown, the DC buck chopper circuit achieves an output range of 0V to 600V. The entire system consists of two identical DC control units, each employing an IGBT modular design and an interleaved parallel waveform generation method. The four BUCK circuits have PWM phase differences of 90 degrees, achieving energy complementarity and significantly reducing the current stress on individual IGBT transistors during high-current operation. Due to the IGBT modular design, the upper and lower bridge arms also use complementary waveform generation, thus achieving bidirectional energy conversion. The test system is current-controlled; to ensure current response characteristics and good current ripple characteristics, the inductor design controls the current ripple rate to within 0.2% of the rated current. Furthermore, based on the cutoff frequency calculation method, the output current control loop ripple is minimized. Low-resistance film capacitors are selected for the filter capacitors, and multiple capacitors are connected in parallel. Each DC-DC power supply uses four inductors connected in parallel, and the inductor current is sampled as a reference quantity for the control loop. This part of the design uses a current negative feedback method to adjust the output current in real time. Combined with an optimized PID regulator circuit, the output current is controlled with a fast response speed on the basis of output stability, ensuring that the amplitude-frequency and phase-frequency characteristics of its closed-loop control are optimized, further ensuring the fast response characteristics of current conversion. When PWM high-frequency switching is used to achieve inversion, high-order harmonic components will inevitably be coupled in the output waveform. In this part of the design, an optimized design is adopted to add specific harmonic filtering on the basis of output LC filtering, effectively reducing the distortion and high-order harmonic content of the output waveform.

[0034] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A combined main and auxiliary power supply system, including a main power supply, characterized in that: The main power supply is connected to an auxiliary power supply. Both the main power supply and the auxiliary power supply are electrically connected to the main control cabinet. The output of the main control cabinet is connected to the load through a commutator cabinet. The auxiliary power supply includes a circuit breaker. The power grid is connected to a soft starter circuit through the circuit breaker. The soft starter circuit is connected in series with an isolation transformer T1. The isolation transformer T1 is connected to an AC / CDC optimization circuit. The AC / CDC optimization circuit is connected to a DC / CDC alternating step-down chopper circuit.

2. The main and auxiliary power supply system according to claim 1, characterized in that: The soft start circuit includes AC contactors KM1 and KM2 connected in parallel, and the AC contactors are connected in parallel with resistors R.

3. The main and auxiliary power supply system according to claim 2, characterized in that: The three-phase output of the power grid is connected to the input terminal of circuit breaker QF. The output terminal of circuit breaker QF is connected to the input terminals of AC contactor KM1 and AC contactor KM2 respectively. The three-phase output terminals of AC contactor KM2 are respectively connected to resistors R1, R2 and R3. The output terminals of resistors R1, R2 and R3 are connected to the three output terminals of AC contactor KM1 and then connected to the input terminal of isolation transformer T1.

4. The main and auxiliary power supply system according to claim 3, characterized in that: The AC / CDC optimization circuit includes a capacitor C1 and an inductor L connected to an isolation transformer T1. The three-phase output terminals of the isolation transformer T1 are respectively connected to the three input terminals of the inductor L. The three output terminals of the inductor L are respectively connected to three current sensors LEM. The three current sensors LEM are respectively connected to two IGBT single transistors connected in series. The three sets of IGBT single transistors connected in series are connected in parallel and then connected to a capacitor C2.

5. The main and auxiliary power supply system according to claim 4, characterized in that: The DC-DC interleaved step-down chopper circuit includes a fuse FU1 connected to capacitor C2 and a resistor R2. Resistor R2 is connected in parallel with capacitor C3. Four sets of IGBT single transistors are connected in series in parallel with capacitor C3. The four sets of IGBT single transistors are connected in parallel to four inductors L. One end of each inductor L is connected in series with a current sensor LEM. The current sensor LEM is connected to capacitor C4.

6. The main and auxiliary power supply system according to claim 5, characterized in that: The DC-DC interleaved buck chopper circuit adopts an interleaved parallel waveform generation method, and the four BUCK circuits have a PWM phase difference of 90 degrees.

Images