Ozone generator power supply preceding-stage active voltage-sharing circuit topology applied to high-voltage system

Abstract

The invention discloses an ozone generator power supply pre-stage active voltage-sharing circuit topology applied to a high-voltage system, which comprises a resonant branch, two-way buck-boost converter switch bridges and a two-way buck-boost converter resonant branch, N two-way buck-boost converter switch bridges are formed by connecting a first switch bridge and a second switch bridge in series, the other end of the first switch bridge is connected in parallel to a PP parallel connection point of a circuit of the ozone generator power supply module, and the other end of the second switch bridge is connected in parallel to a Pn parallel connection point of the circuit of the ozone generator power supply module; the N bidirectional buck-boost converter resonant branches comprise a first resonant inductor and a first capacitor which are connected in series, and a second resonant inductor which is connected in parallel with the first capacitor. The voltage-sharing circuit can realize the same input voltage of each ozone generator power supply module, and ensures the same output characteristics of the ozone generator power supply modules, so that the working state consistency of the ozone generator is high, and the overall efficiency and life cycle of an ozone system are effectively improved.

Description

Technical Field

[0001] The invention relates to an active voltage balancing control technology, and in particular to an active voltage balancing circuit topology for a front stage of an ozone generator power supply applied to a high voltage system. Background Art

[0002] Ozone's strong oxidizing and sterilizing abilities make it widely used in many fields such as the semiconductor industry, water treatment, chemical oxidation, food processing, and medical and health care. Ozone is a strong oxidant second only to fluorine, and effective use of ozone can greatly improve our living conditions and environment. The benefits of ozone mainly lie in its ability to oxidize pollutants. Ozone gas itself is unstable, so it must be prepared on site when used. The product of ozone decomposition is oxygen, so ozone is an environmentally friendly oxidant.

[0003] Ozone is produced by dielectric barrier discharge. Dielectric barrier discharge is a gas discharge method that puts an insulating medium into the discharge space. An insulating dielectric is placed between two parallel high-voltage electrodes, and the discharge gap must maintain a certain distance. When a high-voltage power supply is connected, an alternating high-voltage electric field and magnetic field will be generated. When dry air or oxygen passes through the discharge channel, oxygen molecules are excited by high-energy electrons and gain energy, and collide with each other to form ozone molecules.

[0004] The core equipment of the ozone generator system to produce ozone is the ozone generator power supply. The traditional ozone generator power supply adopts a centralized power supply mode with weak fault tolerance. Once the power supply fails, the entire ozone system stops working, seriously affecting production.

[0005] The module integration solution is adopted to ensure the continuity and stability of industrialized ozone production. Each module in the system is independent of each other. When a problem occurs in one module, other modules work normally without affecting the operation of the whole machine, thus ensuring continuous production for users. At the same time, the power module adopts a modular design solution, which increases the redundancy and fault tolerance of the system. The existing technical solution of the power module adopts a series mode input voltage directly connected to the DC bus solution, that is, the three-phase high-voltage AC is converted to DC through uncontrolled rectification or controlled rectification, and all power modules are directly connected in series to the public DC bus. Due to the different equivalent impedances of each power module, the input voltage and output power of each power module are different, which in turn affects the output stability and the life of the module. Summary of the invention

[0006] In view of the above-mentioned defects or deficiencies in the prior art, it is desirable to provide an active voltage equalizing circuit topology for the front stage of an ozone generator power supply applied to a high voltage system.

[0007] According to the technical solution provided in the embodiment of the present application, the active voltage-equalizing circuit topology of the front stage of the ozone generator power supply applied to the high-voltage system is characterized in that it includes a resonant branch, a bidirectional buck-boost converter switch bridge and a bidirectional buck-boost converter resonant branch, The N bidirectional buck-boost converter switch bridges are composed of a first switch bridge S ia (i=1,2,3...n) and the second switch bridge S ib (i=1,2,3...n) are arranged alternately and connected in series, the first switch bridge S 1a The other end of (a=1,2,3...n) is connected in parallel to the first parallel terminal P of the circuit of the ozone generator power module P On the second switch bridge S 2b The other end of (b=1,2,3...n) is connected in parallel to the second parallel terminal P of the circuit of the ozone generator power module n superior; The first adjacent switch bridge S 1a (a=1,2,3...n) and the second switch bridge S 2b (b=1,2,3...n) has a parallel point P between them Im (m=1,2,3...n), several parallel points P Im (m=1,2,3...n) are connected in series; The N bidirectional buck-boost converter resonant branches include a first resonant inductor L connected in series ri (i=1,2,3...n) and the first capacitor C ri (i=1,2,3...n) and connected in parallel to the first capacitor C ri The second resonant inductor L on (i=1,2,3...n) i (i=1,2,3...n), the first capacitor C ri The other end of (i=1,2,3...n) is connected in parallel to the parallel point P between two adjacent ozone generator power modules. Im (m=1,2,3...n), The N resonant branches of the bidirectional buck-boost converter are connected via N-1 resonant branches, and the N-1 resonant branches are connected in series.

[0008] In the present invention, further, the resonant branch is a third resonant inductor L pi (i=1,2,3...n-1) and the second capacitor C Pi (i=1,2,3...n-1) are connected in series.

[0009] In the present invention, further, the ozone generator power module includes first ozone generator power modules B alternately arranged and connected in series. ia (i=1,2,3...n) and the second ozone generator power module B ib (i=1,2,3...n).

[0010] 2n ozone generator power modules are connected in parallel to the output capacitor B of the voltage equalization circuit 1a -B nb The voltage balancing circuit topology is designed as a multi-layer voltage balancing topology structure, and the basic voltage balancing units of Layer1-Layerm are the same, such as Figure 2 The voltage equalization circuit has a fast voltage equalization effect and excellent dynamic characteristics.

[0011] In summary, the beneficial effects of this application are: 1. Ensure that the input voltage of the front stage of the modular ozone generator power supply is the same, and the output power of each module power supply is the same, so that the consistency of the system is improved and the stability is high. At the same time, the balancing path and balancing threshold can be adjusted in the dynamic process; the voltage balancing circuit greatly reduces the number and voltage level of switches at the same voltage level, and all switch tubes can realize ZVS and ZCS opening and closing, thereby improving efficiency, power density and system stability; Second, the voltage equalization circuit can achieve the same input voltage for each ozone generator power module, ensuring the same output characteristics of the ozone generator power modules, thereby achieving high consistency in the working state of the ozone generators, effectively improving the overall efficiency and life cycle of the ozone system. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings: Figure 1 It is a schematic diagram of the topological structure of the voltage equalizing converter of the present invention; Figure 2 It is a schematic diagram of the topological structure of the balancing sub-circuit in the present invention; Figure 3 It is a schematic diagram of four working modes in one switching cycle of the present invention; Figure 4 Schematic diagram of theoretical waveform of voltage equalizing converter in the present invention. DETAILED DESCRIPTION

[0013] The present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant invention, rather than to limit the invention. It is also necessary to explain that, for ease of description, only the parts related to the invention are shown in the accompanying drawings.

[0014] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0015] As shown Figure 1 and Figure 2 As shown, n bidirectional buck-boost converter switch bridges (S 1a , S 1b ), (S 2a , S 2b ),……(S na , S nb ) in P p and P n Between them, n-1 resonant branches (L p1 , C p1 ), L p2 , C p2 ),…(L p(n-1) , C p(n-1) ) and n bidirectional buck-boost converter resonant branches (L r1 , C r1 ), L r2 , C r2 ),...(L rn , C rn ), are composed of resonant inductors and capacitors, respectively connected to the switch bridge (P i1 -P in ) connection, L1, L2, ... L n The inductor of the bidirectional buck-boost converter is 2n+1 level VBC, which can realize voltage self-balancing under various working conditions.

[0016] The topological model of the balanced subcircuit is shown in the attached Figure 2 In the figure, two bidirectional buck-boost converter switch bridges (S 1a , S 1b ), (S 2a , S 2b ) in P p and P n between them in series, 1 resonant branch (L p1 , C p1 ) and two bidirectional buck-boost converter resonant branches (L r1 , C r1 ), L r2 , C r2 ) consists of a resonant inductor and capacitor, respectively connected to the switch bridge (P i1 -P i2) connection, L1 and L2 are bidirectional buck-boost converter inductors. The VBC unit can achieve voltage self-balancing under various working conditions.

[0017] The basic principle of VBC voltage balancing is similar to that of switched capacitor based power conversion. To analyze the working principle of VBC cell, the following assumptions are made.

[0018] 1) All devices are ideal and parasitic parameters can be ignored.

[0019] 2) (L p1 , C p1 ) has a resonant period of T p , (L r1 , C r1 ) and (L r2 , C r2 ) has a resonant period of T r , (S 1a , S 1b ) and (S 2a , S 2b ) has a switching period of T s , the dead time of the switch is T d .

[0020] 3) Resonance period T p Approximately equal to (T s –2T d ), and T p =2T r , that is, ωr=2ωp. The theoretical waveform of the VBC unit is as follows Figure 4 According to the theoretical waveform, there are four working modes in one switching cycle, such as Figure 3 shown.

[0021] Mode I (t0–t1): At t0, S 1a and S 2a In the open state, S 1b and S 2b In the off state. The resonant capacitor C p1 By battery B 1a , B 1b By S 1a , L p1 , C p1 and S 2a The circuit composed of the two is charged. The resonant current i Lp1 will increase from 0 at t0 and then oscillate back to 0 at t1. At the same time, the resonant capacitor C r1 By battery B 1a By S 1a , L r1 and C r1The circuit composed of charging and discharging, inductor L1 and C r1 The voltages at both ends of the parallel connection are equal, so the inductor L1 can store energy, and the resonant current i Lr1 will increase from 0 at t0 and then oscillate back to 0 at t1; the resonant capacitor C r2 By battery B 2a By S 2a , L r2 and C r2 The circuit composed of charging and discharging, inductor L2 and C r2 The voltages at both ends of the parallel connection are equal, so the inductor L2 can store energy, and the resonant current i Lr2 will increase from 0 at t0 and then oscillate back to 0 at t1. Therefore, in this mode, S 1a and S 2a Zero current can be turned on. The working principle diagram of mode I is as follows: Figure 3 (a), the quantitative expression is as follows: (1) in , I L1 is the average current of inductor L1, and the peak current value in formula (1) is derived as follows: s ) inside, B 1a , B 1b Discharge through the resonant branch, the discharge current is i Lp1 (t), according to the law of conservation of charge, , assuming that the discharge current i Lp1 (t) is a sinusoidal current, which can be used It means that the peak value I can then be Lp1 Calculated as .

[0022] Mode II (t1–t2): At time t1, S 1a and S 2a Closed because the resonant current i Lp1 、i Lr1 and i Lr2 It has oscillated back to 0, so S1a and S2a can achieve zero current shutdown. In this mode, all switches are in the off state.

[0023] Mode III (t2–t3): At t2, S 1b and S 2b In the open state, S 1a and S 2a In the off state, battery B 2a , B 2b By the resonant capacitor C p1 By S 1b , Lp1 , C p1 and S 2b Loop charging, resonant current i Lp1 It will increase from 0 at t2 and then oscillate back to 0 at t3. At the same time, the resonant capacitor C r1 By battery B 1b By S 1b , L r1 and C r1 The circuit composed of charging and discharging, inductor L1 and C r1 The voltages at both ends of the parallel connection are equal, so the inductor L1 releases energy and the resonant current i Lr1 will increase from 0 at t2 and then oscillate back to 0 at t3; the resonant capacitor C r2 By battery B 2b By S 2b , L r2 and C r2 The circuit composed of charging and discharging, inductor L2 and C r2 The voltages at both ends of the parallel connection are equal, so the inductor L2 releases energy and the resonant current i Lr2 will increase from 0 at t2 and then oscillate back to 0 at t3. Therefore, in this mode, S 1b and S 2b Zero current can be turned on. The working principle diagram of mode III is as follows: Figure 3 (c) is shown, and the quantitative expression is as follows: (2) Mode IV (t3–t4): At time t3, S 1b and S 2b Turn off, due to the resonant current i Lp1 、i Lr1 and i Lr2 Oscillates back to 0, S 1b and S 2b Zero current shutdown can be achieved. As in mode II, all switches are in the off state. The duty cycle and frequency of the drive pulse of the VBC unit are fixed, then each half bridge uses a complementary drive pulse with a duty cycle of 50%, and the drive pulses of all half bridges are synchronized.

[0024] According to the above analysis, for the VBC unit, according to the initial condition B 1a , B 1b and B 2a , B 2b The energy in the battery can be transferred to each other, and finally reach equilibrium after multiple cycles. Therefore, for the proposed VBC 2n batteries (B 1a , B 1b , B 2a , B 2b , … Bna , B nb ) can achieve power balance, and at the same time, B na and B nb The power in the circuit can also be balanced according to the basic principle and control strategy of bidirectional buck-boost. For the VBC unit in mode I, assuming B 1a , B 1b The voltage and is a constant DC value without any ripple. According to the basic resonance principle, when the resonance is in a steady state, the voltage of the resonant capacitor and the current of the resonant inductor can be expressed as: (3) Among them, I L1 and I L2 are the average values ​​of inductance L1 and L2 in two resonant cycles, and the resonant inductance L p1 The initial current value is 0, and the resonant capacitor C p1 The initial voltage value is , resonant inductor L r1 The initial current value is 0, and the resonant capacitor C r1 The initial voltage value is , resonant inductor L r2 The initial current value is 0, the resonant capacitor C r2 The initial voltage value is 0, and the solution of differential equation (3) is: (4) (5) (6) (7) in, , .

[0025] For mode III, according to the basic resonance principle, when the resonance is in steady state, the voltage of the resonant capacitor and the current of the resonant inductor can be expressed as: (8) Resonant inductor L p1 The initial current value is 0, and the resonant capacitor C p1 The initial voltage value is , resonant inductor L r1 The initial current value is 0, and the resonant capacitor C r1 The initial voltage value is , resonant inductor L r1 The initial current value is 0, and the resonant capacitor C r1 The initial voltage value is 0, and the solution of differential equation (8) is: (9) (10) (11) (12) From formula (1), we can know that the voltage of the resonant capacitor at time t1 is: , then ,again , from formula (10) we can get: (13) Combining equation (2) and equation (13), we can get: (14) From (14), we can see that the input voltage is equalized.

[0026] The above description is only an explanation of the preferred embodiments of the present application and the technical principles and other schemes used. At the same time, the scope of the invention involved in the present application is not limited to the technical scheme formed by a specific combination of the above technical features, but also includes other technical schemes formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the above features are replaced with the technical features with similar functions disclosed in the present application (but not limited to) to form a technical scheme.

Claims

1. The active voltage equalization circuit topology of the front stage of the ozone generator power supply used in the high-voltage system is characterized by: It includes a resonant branch, a bidirectional buck-boost converter switch bridge and a bidirectional buck-boost converter resonant branch. The N bidirectional buck-boost converter switch bridges are composed of a first switch bridge S ia (i=1,2,3...n) and the second switch bridge S ib (i=1,2,3...n) are arranged alternately and connected in series, the first switch bridge S 1a The other end of (a=1,2,3...n) is connected in parallel to the first parallel terminal P of the circuit of the ozone generator power module P The second switch bridge S 2b The other end of (b=1,2,3...n) is connected in parallel to the second parallel terminal P of the circuit of the ozone generator power module n superior; The first adjacent switch bridge S 1a (a=1,2,3...n) and the second switch bridge S 2b (b=1,2,3...n) has a parallel connection point P between them Im (m=1,2,3...n), a number of said parallel connection points P Im (m=1,2,3...n) are connected in series; The N bidirectional buck-boost converter resonant branches include a first resonant inductor L connected in series ri (i=1,2,3...n) and the first capacitor C ri (i=1,2,3...n) and connected in parallel to the first capacitor C ri The second resonant inductor L on (i=1,2,3...n) i (i=1,2,3...n), the first capacitor C ri The other end of (i=1,2,3...n) is connected in parallel to the parallel point P between two adjacent ozone generator power modules. Im (m=1,2,3...n), The N resonant branches of the bidirectional buck-boost converter are connected via N-1 resonant branches, and the N-1 resonant branches are connected in series.

2. According to claim 1, the active voltage equalizing circuit topology for the front stage of the ozone generator power supply applied to the high voltage system is characterized by: The resonant branch is a third resonant inductor L pi (i=1,2,3...n-1) and the second capacitor C Pi (i=1,2,3...n-1) are connected in series.

3. According to claim 1, the active voltage equalizing circuit topology for the front stage of the ozone generator power supply applied to the high voltage system is characterized by: The ozone generator power module comprises first ozone generator power modules B which are alternately arranged and connected in series. ia (i=1,2,3...n) and the second ozone generator power module B ib (i=1,2,3...n).

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