A rectifier power supply system for a high power electric hob

Abstract

This application relates to the field of electric stove technology, specifically to a rectifier power supply system for a high-power electric stove, comprising: an AC power receiving device for receiving AC power from the power grid and converting the AC power into a first DC load; a DC power receiving device for receiving DC power stored in a photovoltaic power generation system and converting the DC power into a second DC load; and a common DC bus for receiving the first DC load and the second DC load, and mixing the first DC load and the second DC load to generate a mixed DC load; the solution provided in this application can adjust the mixing ratio of the first DC load and the second DC load.

Description

Technical Field

[0001] This application relates to the field of electric stove technology, and more specifically, to a rectifier power supply system for a high-power electric stove. Background Technology

[0002] The content in this section provides only background information related to this application and may not constitute prior art.

[0003] High-altitude settlements are generally scattered and far from power grid load centers, making the extension of large power grids difficult due to high overhead line costs and stringent environmental constraints. High-altitude areas can typically only provide basic electricity for daily life, insufficient to support large-scale electricity demand. Against this backdrop, electricity is commonly used as the primary energy source for cooking in high-altitude regions.

[0004] Traditional induction cookers heat cookware using electromagnetic induction, producing no open flame during cooking—a flameless heating method. Lacking the high-temperature stir-frying conditions and "wok hei" (wok aroma) characteristic of open-flame cooking, dishes cooked on induction cookers differ significantly from those cooked over an open flame in color, aroma, and texture. To improve cooking quality and achieve a taste closer to traditional open-flame cooking, more and more users are choosing electric gas stoves. Electric gas stoves utilize high-voltage ionization of air to generate plasma flames, simulating the flame pattern of a gas stove. They can reach temperatures exceeding 1200℃, meeting the high-temperature stir-frying requirements of Chinese cooking.

[0005] To achieve heating effects comparable to open-flame cooking, electric stoves need to maintain high output power. Currently, commercially available electric stoves typically have a power output between 2500W and 3500W. Some products, operating at their rated power, place a significant instantaneous load on the power grid. The power grid infrastructure in high-altitude areas is generally sparse and has limited capacity, making it difficult to withstand excessively high electrical loads. The high-power characteristics of electric stoves further exacerbate the burden on the power grid, easily causing tripping and voltage drops during peak electricity consumption periods, severely impacting the normal use and promotion of electric stoves in high-altitude areas. Summary of the Invention

[0006] The summary section of this application is intended to provide a brief overview of the concepts, which will be described in detail in the detailed description section below. This summary section is not intended to identify key or essential features of the claimed technical solutions, nor is it intended to limit the scope of the claimed technical solutions.

[0007] Some embodiments of this application propose a rectifier power supply system for a high-power electric stove to solve the technical problems mentioned in the background section above.

[0008] A rectifier power supply system for a high-power electric stove, comprising: An AC power receiving device is used to receive AC power from the power grid and convert the AC power into a first DC load; A DC receiving device is used to receive DC power stored in a photovoltaic power generation system and convert the DC power into a second DC load. A common DC bus receives a first DC load and a second DC load, and mixes the first DC load and the second DC load to generate a mixed DC load. The high-voltage generator converts the mixed DC load into a high-voltage current and sends it to the electrodes of the electric stove to produce an open flame. The control device controls the size of the mixed load based on the power demand provided by the user, and controls the mixing ratio of the first DC load and the second DC load based on the power supply margin of the photovoltaic power generation system and the power supply margin of the power grid.

[0009] This application uses an AC receiving device and a DC receiving device to rectify the power from the power grid and clean energy sources into DC loads with controllable current, and then mixes them on a common DC bus. The control device then dynamically adjusts the mixing ratio of the two sources according to the power demand of the user and the power supply margin on both sides. This ensures the high power required for open flame cooking in electric stoves while reducing the instantaneous load impact on the power grid as needed, and alleviates problems such as tripping and voltage drops that are prone to occur in weak power grids at high altitudes and other areas during peak electricity consumption periods.

[0010] Furthermore, the AC receiving device includes: The 220V AC input terminal is connected to the power grid to receive 220V AC power. EMI filter / rectifier bridge / filter capacitor converts 220V, 50Hz AC power into DC current; The controlled isolated DC / DC converter I converts DC current into a first DC load whose current magnitude can be controlled.

[0011] The AC receiving device first rectifies the AC power from the grid into DC power through an EMI filter / rectifier bridge / filter capacitor, and then converts it into a first DC load with a controllable current through a controlled isolated DC / DC converter I, so that the output power on the grid side can be precisely adjusted, which is convenient for subsequent proportional distribution on the bus.

[0012] Furthermore, the controlled isolated DC / DC converter I includes: The first primary-side full bridge includes switch Q1, switch Q2, switch Q3, and switch Q4. Switch Q1 and switch Q2 form the first left bridge arm, and switch Q3 and switch Q4 form the first right bridge arm. The midpoints of the two bridge arms are denoted as A and B, respectively. The LLC resonant cavity includes a resonant inductor Lr, a resonant capacitor Cr, and a transformer magnetizing inductor Lm. The first isolation transformer is used to achieve electrical isolation between the primary and secondary sides and to change the turns ratio. The first secondary rectifier bridge is connected to the first isolation transformer and is used to rectify high-frequency AC into DC. Wherein, the first end of the resonant inductor Lr is connected to node A, the second end of the resonant inductor Lr is connected to the first end of the resonant capacitor Cr; the second end of the resonant capacitor Cr is connected to the first end of the primary winding of the first isolation transformer; the second end of the primary winding of the first isolation transformer is connected to node B, and the magnetizing inductance Lm is the magnetizing inductance of the first isolation transformer itself, which is equivalent to being connected in parallel between the first end and the second end of the primary winding of the first isolation transformer.

[0013] The controlled isolated DC / DC converter I adopts a topology combining a full-bridge and LLC resonant cavity, which can achieve soft switching of the switching transistors over a wide load range, thereby significantly reducing switching losses, improving conversion efficiency and reducing electromagnetic interference, making it suitable as a long-term main power grid branch; at the same time, the first isolation transformer achieves electrical isolation between the primary and secondary sides, improving system safety.

[0014] Furthermore, the controlled isolated DC / DC converter I also includes an output capacitor Co, with the first end of the output capacitor Co connected to the positive DC output terminal of the first secondary rectifier bridge, and the second end of the output capacitor Co connected to the negative DC output terminal of the first secondary rectifier bridge.

[0015] The output capacitor Co filters and smooths out the ripple of the rectified voltage, providing a stable DC output for the first DC load.

[0016] Furthermore, the control device controls the first DC load by controlling the switching transistors Q1 to Q4 to conduct at a frequency that is diagonally opposite.

[0017] The control device can change the gain of the LLC resonant cavity by changing the frequency of the diagonal conduction of the switching transistors Q1 to Q4 (i.e., the switching frequency fs), thereby continuously and accurately adjusting the size of the first DC load, so that the AC receiving device presents itself as a controlled current source with controllable output current.

[0018] Furthermore, the DC receiving device includes: The 48V DC input terminal is connected to the energy storage battery of the photovoltaic power generation system to receive 48V DC power. Input filter, used to smooth current ripples on the energy storage battery side; The controlled isolated DC / DC converter II converts DC current into a second DC load whose current magnitude can be controlled.

[0019] The DC receiving device first smooths the current ripple on the energy storage battery side through the input filter, and then converts the low-voltage DC power stored in the clean energy into a second DC load with controllable current through the controlled isolated DC / DC converter II, so that the output of the clean energy side can be precisely adjusted and matched proportionally with the grid side.

[0020] Furthermore, the controlled isolated DC / DC converter II includes: The second primary-side full bridge includes switch Q5, switch Q6, switch Q7, and switch Q8; switch Q5 and switch Q6 form the second left bridge arm, and switch Q7 and switch Q8 form the second right bridge arm; the midpoints of the two bridge arms are denoted as node M and node N, respectively. The second isolation transformer is used to achieve electrical isolation between the primary and secondary sides and to change the step-up ratio; The second auxiliary rectifier bridge is connected to the second isolation transformer and is used to rectify high-frequency AC into DC. The output filter circuit, including the output inductor Lo and the second output capacitor Co2, is used to smooth the intermittent block voltage after rectification into a flat DC. Current sensor A2 is used to monitor the magnitude of the second DC load; Among them, the first end of the primary winding of the second isolation transformer is connected to node M, and the second end of the primary winding is connected to node N; The positive DC output terminal of the second secondary rectifier bridge is denoted as node S, and the negative DC output terminal of the second secondary rectifier bridge is denoted as node T. The first end of the output inductor Lo is connected to node S, and the second end of the output inductor Lo is denoted as node K; the first end of the second output capacitor Co2 is connected to node K, and the second end of the second output capacitor Co2 is connected to node T; the current sensor A2 is connected in series between node K and the positive terminal of the common DC bus; node T is connected to the negative terminal of the common DC bus.

[0021] The controlled isolated DC / DC converter II adopts a full-bridge boost topology with a second isolation transformer. It relies on the transformer turns ratio to significantly boost the low-voltage DC of the energy storage battery to the bus voltage level. The output inductor Lo and the second output capacitor Co2 smooth the discontinuous voltage after rectification into a flat DC, so that the output can remain stable even when the input voltage fluctuates with the battery state of charge. The second isolation transformer also realizes electrical isolation between the battery side and the bus side, improving safety.

[0022] Furthermore, the control device controls the second DC load by controlling the duty cycle D of the switching transistors Q5 to Q8.

[0023] The control device can change the energy transferred to the secondary side in each switching cycle by adjusting the duty cycle D of the switching transistors Q5 to Q8, thereby continuously and accurately adjusting the size of the second DC load, so that the DC receiving device presents itself as a controlled current source with controllable output current.

[0024] Furthermore, the common DC bus includes: positive bus, negative bus, and bus voltage regulator capacitor bank Cbus; The outputs of controlled isolated DC / DC converter I and controlled isolated DC / DC converter II are both connected in parallel between the positive bus and the negative bus; No isolation diodes are installed on the positive busbar; The first end of the bus voltage regulator capacitor bank Cbus is connected to the positive bus, and the second end is connected to the negative bus.

[0025] Controlled isolated DC / DC converter I and controlled isolated DC / DC converter II are directly connected in parallel between the positive bus and the negative bus as two controlled current sources. The two currents are linearly superimposed on the bus to form a mixed DC load, which facilitates mixed power supply in any proportion. The bus voltage stabilizing capacitor bank Cbus is used to stabilize the bus voltage, store energy and absorb the ripple generated by the two branch switches. It supports the bus voltage in time when the output of any branch changes suddenly or switches, ensuring stable power supply and seamless switching.

[0026] Furthermore, the control device includes Central controller; The first gate drive circuit has its input terminal connected to the central controller and its output terminal connected to the control terminals of the switching transistors Q1, Q2, Q3, and Q4 in the controlled isolated DC / DC converter I. The second gate drive circuit has its input terminal connected to the central controller and its output terminal connected to the control terminals of switching transistors Q5, Q6, Q7, and Q8 in the controlled isolated DC / DC converter II, respectively. The third gate drive circuit has its input terminal connected to the central controller and its output terminal connected to the control terminal of the switching transistor in the high voltage generator. The signal sampling circuit is used to acquire data from the first DC load, the second DC load, and the mixed DC load. The central controller controls the opening and closing of switches Q1, Q2, Q3, Q4, Q5, Q6, Q7, and Q8 based on the sampling results from the signal sampling circuit.

[0027] The control device, through the cooperation of the central controller, the first to third gate drive circuits and the signal sampling circuit, drives the switching tubes of the two converters and the high-voltage generator respectively according to the sampled branch current and bus status, so as to achieve unified and coordinated control of the output ratio and firepower of the two circuits.

[0028] Furthermore, the control device employs dual closed-loop control to achieve power distribution, specifically including an inner loop and an outer loop; The inner loop is a constant current loop for each branch. The central controller controls the controlled isolated DC / DC converter I and the controlled isolated DC / DC converter II to output a controllable first load current and a second load current respectively. The outer ring is a power distribution and bus clamping ring. The central controller obtains the total current reference based on the power demand provided by the user end, and determines the mixing ratio k of the first DC load and the second DC load based on the power supply margin of the photovoltaic power generation system and the power supply margin of the grid. The first load current and the second load current are adjusted according to the mixing ratio k.

[0029] The control device uses an inner loop (constant current loops for each branch) to ensure that the two converters output controllable first and second load currents respectively, each exhibiting controlled current source characteristics; and an outer loop (power distribution and bus clamping loop) to determine the mixing ratio k based on power demand and the power supply margin on both sides, thereby distributing the current reference and clamping the bus voltage to the set value. In this way, while meeting the user's thermal power demand, the device accurately and stably controls the output ratio of the power grid and clean energy, minimizing the load on the power grid. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the rectifier power supply system for a high-power electric stove.

[0031] Figure 2 This is a schematic diagram of an AC power receiving device.

[0032] Figure 3 This is a schematic diagram of a DC receiving device.

[0033] Figure 4 This is a schematic diagram of a common DC bus.

[0034] Figure 5 This is a block diagram of the control device. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below in conjunction with specific embodiments. The same reference numerals in the accompanying drawings represent the same components. It should be noted that the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the described embodiments of this application without creative effort are within the scope of protection of this application.

[0036] Compared to the embodiments shown in the accompanying drawings, feasible embodiments within the scope of this application may have fewer components, other components not shown in the drawings, different components, differently arranged components, or components with different connections, etc. Furthermore, two or more components in the drawings may be implemented in a single component, or a single component shown in the drawings may be implemented as multiple separate components.

[0037] Unless otherwise defined, the technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this application pertains. The terms “first,” “second,” and similar terms used in this specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms “an” or “a” and similar terms do not necessarily indicate a quantity limitation. Terms such as “upper” and “lower” are used only to indicate relative positional relationships, and these relative positional relationships may change accordingly when the absolute position of the described object changes.

[0038] The working principle of an electric stove is as follows: the built-in high-voltage generating circuit boosts the mains electricity (220V / 50Hz) to a high voltage of several thousand volts or even tens of thousands of volts, and applies it between the discharge electrodes on the stove surface. This causes the air in the gap between the electrodes to be broken down and ionized by the strong electric field, generating a continuous and stable plasma arc (i.e., artificial open flame). The temperature of this arc can reach over 1200℃, which can simulate the flame shape of a traditional gas stove, thereby achieving open flame heating and cooking of cookware.

[0039] Electric stoves have a high load, and cooking time is very concentrated. Therefore, if all residents in the settlement use electric stoves at the same time, it can easily lead to an overload of the power grid, resulting in power outages.

[0040] Based on this, this application provides a rectifier power supply system for a high-power electric stove. The principle is as follows: utilizing photovoltaic power generation systems common in high-altitude areas, a portion of electrical energy is pre-stored in the battery. When the stove needs power, the power grid and the battery simultaneously supply power, adjusting the output ratio of the power grid and the battery to reduce the load on the power grid.

[0041] Photovoltaic power generation systems are a common energy source in high-altitude areas. High-altitude areas have abundant sunshine, and most households typically install photovoltaic power generation systems beforehand. These systems generally include solar energy receiving devices and solar energy storage devices (batteries). This solution utilizes the solar energy storage device as an alternative power source for the electric stove, thereby reducing the load on the power grid.

[0042] Therefore, in practice, a suitable power supply scheme can be selected based on the amount of sunshine and solar energy storage. When solar energy is abundant and batteries have sufficient energy storage, direct solar power supply can reduce emissions, lower electricity prices, and reduce the load on the power grid.

[0043] Of course, in practice, a storage battery can also be directly connected. This storage battery is charged at night or during off-peak electricity prices, and then discharged to power the stove during subsequent cooking.

[0044] The key to this solution is to utilize energy storage batteries to mitigate the load on the power grid when electric stoves are used in concentrated areas, thus preventing power outages. Maintenance of the energy storage batteries can be configured according to requirements. In this solution, the energy storage batteries are charged using solar energy receiving equipment.

[0045] refer to Figure 1 Example 1: A rectifier power supply system for a high-power electric stove, comprising: an AC power receiving device, a DC power receiving device, a common DC bus, and a control device, wherein: An AC power receiving device is used to receive AC power from the power grid and convert the AC power into a first DC load; A DC receiving device is used to receive DC power stored in a photovoltaic power generation system and convert the DC power into a second DC load. A common DC bus receives a first DC load and a second DC load, and mixes the first DC load and the second DC load to generate a mixed DC load. The high-voltage generator converts the mixed DC load into a high-voltage current and sends it to the electrodes of the electric stove to produce an open flame. The control device controls the size of the mixed load based on the power demand provided by the user, and controls the mixing ratio of the first DC load and the second DC load based on the power supply margin of the photovoltaic power generation system and the power supply margin of the power grid.

[0046] In this scheme, the grid power supply and battery power supply are processed separately using AC and DC receiving devices, then mixed on a common DC bus before subsequent voltage boosting. This is because the current from the grid power supply and battery power supply are not uniform; directly connecting them to the DC bus could easily cause a short circuit in the power system, or make it difficult to control the output ratio of the grid and battery power according to the required proportion.

[0047] In this application, the AC receiving device and the DC receiving device are responsible for integrating the received power into a unified DC power, combining it onto a common DC bus, and can adjust the size of the first DC load and the second DC load at any time, thereby controlling the ratio of the first DC load and the second DC load in the mixed DC load.

[0048] The high-voltage generating device is used to amplify the mixed load to the required high-voltage current. The high-voltage generating device is a core component in existing electric stoves and belongs to the prior art. This application will not further disclose its specific circuit structure.

[0049] The key to this application is to adjust the size of the mixed load and the ratio of the first DC load and the second DC load in the mixed load according to the power requirements.

[0050] The key to this application lies in how to adjust the first DC load and the second DC load, and how to combine the adjusted first DC load and the second DC load onto the common DC bus so that the two can output power in proportion.

[0051] This application provides the following more specific solutions: refer to Figure 2 The AC receiving device includes a 220V AC input terminal, an EMI filter / rectifier bridge / filter capacitor, and a controlled isolated DC / DC converter I.

[0052] The 220V AC input terminal, EMI filter / rectifier bridge / filter capacitor, and controlled isolated DC / DC converter I are connected in sequence.

[0053] The 220V AC input terminal is connected to the power grid to receive 220V AC power.

[0054] The 220V AC input terminal is connected to the power grid, enabling the introduction of 220V, 50Hz AC power.

[0055] The EMI filter / rectifier bridge / filter capacitor converts 220V, 50Hz AC power into approximately 310V DC current. The entire process is as follows: the EMI filter performs high-frequency filtering on the 220V AC power to remove high-frequency interference; the rectifier bridge converts the AC power into "pulsating DC" (0-311V, 100Hz ripple wave); the filter capacitor then smooths out the ripple, resulting in approximately 310V DC power with a small amount of power frequency ripple.

[0056] EMI filters / rectifier bridges / filter capacitors are a common circuit structure in this field, mainly used to convert alternating current (AC) to direct current (DC). However, the power of the converted DC is difficult to control, and when combined with the load bus, it is also difficult to control the output ratio.

[0057] Therefore, a controlled isolated DC / DC converter I is needed to convert 310V DC power with a small amount of power frequency ripple into a current whose magnitude can be controlled.

[0058] The circuit structure of the "EMI filter / rectifier bridge / filter capacitor" will not be described further in this application, as this part is prior art. The specific structure of the controlled isolated DC / DC converter I will be described further below.

[0059] The controlled isolated DC / DC converter I includes: a first primary-side full bridge, an LLC resonant cavity, a first isolation transformer, and a first secondary-side rectifier bridge.

[0060] The first primary-side full bridge includes switch Q1, switch Q2, switch Q3, and switch Q4. Switch Q1 and switch Q2 form the first left bridge arm, and switch Q3 and switch Q4 form the first right bridge arm. The midpoints of the two bridge arms are denoted as A and B, respectively. The LLC resonant cavity includes a resonant inductor Lr, a resonant capacitor Cr, and a transformer magnetizing inductor Lm.

[0061] The first isolation transformer is used to achieve electrical isolation between the primary and secondary sides and to change the turns ratio. The first secondary rectifier bridge is connected to the first isolation transformer and is used to rectify high-frequency AC into DC, which is then filtered by the output capacitor Co.

[0062] The connection relationships of the controlled isolated DC / DC converter I are as follows: The positive and negative output terminals of the EMI filter / rectifier bridge / filter capacitor serve as the positive and negative input terminals of the controlled isolated DC / DC converter I, respectively.

[0063] In the first primary-side full-bridge configuration: the first terminal of switch Q1 is connected to the positive input terminal, and the second terminal of switch Q1 is connected to node A; the first terminal of switch Q2 is connected to node A, and the second terminal of switch Q2 is connected to the negative input terminal; switches Q1 and Q2 are connected in series to form the first left bridge arm. The first terminal of switch Q3 is connected to the positive input terminal, and the second terminal of switch Q3 is connected to node B; the first terminal of switch Q4 is connected to node B, and the second terminal of switch Q4 is connected to the negative input terminal; switches Q3 and Q4 are connected in series to form the first right bridge arm.

[0064] In the LLC resonant cavity: the first end of the resonant inductor Lr is connected to node A; the second end of the resonant inductor Lr is connected to the first end of the resonant capacitor Cr; the second end of the resonant capacitor Cr is connected to the first end of the primary winding of the first isolation transformer; the second end of the primary winding of the first isolation transformer is connected to node B. The magnetizing inductance Lm is the magnetizing inductance of the first isolation transformer itself, which is equivalently connected in parallel between the first and second ends of the primary winding of the first isolation transformer.

[0065] The first end of the secondary winding of the first isolation transformer is connected to the first AC input terminal of the first secondary rectifier bridge, and the second end of the secondary winding of the first isolation transformer is connected to the second AC input terminal of the first secondary rectifier bridge; the positive DC output terminal of the first secondary rectifier bridge is denoted as node G, and the negative DC output terminal of the first secondary rectifier bridge is denoted as node H.

[0066] In the first secondary rectifier bridge: the first end (anode) of diode D1 is connected to the first AC input terminal, and the second end (cathode) of diode D1 is connected to node G; the first end of diode D2 is connected to the second AC input terminal, and the second end of diode D2 is connected to node G; the first end of diode D3 is connected to node H, and the second end of diode D3 is connected to the first AC input terminal; the first end of diode D4 is connected to node H, and the second end of diode D4 is connected to the second AC input terminal.

[0067] The controlled isolated DC / DC converter I also includes an output capacitor Co and a current sensor A1.

[0068] The first end of the output capacitor Co is connected to node G, and the second end of the output capacitor Co is connected to node H.

[0069] Current sensor A1 is connected in series between node G and the positive terminal of the common DC bus; node H is connected to the negative terminal of the common DC bus.

[0070] The isolated DC / DC converter I serves as the main power supply for long-term operation. Its input is approximately 310V DC after rectification, and its output needs to stably supply a controllable current to the bus. An LLC resonant full-bridge converter is chosen here because it can achieve soft switching (the switching transistor operates instantaneously when the voltage or current is zero) over a wide load range. It has extremely low switching losses, high efficiency, and very low electromagnetic interference, making it particularly suitable for long-term continuous operation.

[0071] The steps for implementing power conversion using an isolated DC / DC converter I are as follows: S1: Four switching transistors Q1 to Q4 work in turn to obtain the resonant current; Specifically: Four switching transistors Q1 to Q4 form a "full bridge," divided into two arms: Q1 and Q2 form the left arm, and Q3 and Q4 form the right arm, with midpoints A and B respectively. They operate alternately in a "diagonal conduction" manner. When Q1 and Q4 are both turned on, the current flows from "+" through Q1→A→(LLC resonant cavity)→B→Q4→"-", and +310V is obtained between A and B; After a period of "dead zone" (all four transistors are off), Q2 and Q3 are switched on, resulting in -310V between A and B.

[0072] By alternating in this way, a high-frequency square wave with an amplitude of ±310V and a frequency of fs appears between A and B. The dead zone is to prevent the upper and lower transistors in the same bridge arm from conducting directly and short-circuiting, and it is also the key to achieving soft switching.

[0073] S2: The resonant current flows through the primary winding of the first isolation transformer, inducing a corresponding voltage in the secondary winding of the first isolation transformer to obtain high-frequency alternating current on the secondary side; S3: The high-frequency alternating current on the secondary side is rectified by the full bridge of D1~D4: D1 and D4 conduct in one half-cycle, and D2 and D3 conduct in the other half-cycle, converting the alternating current into direct current, which is then smoothed by the output capacitor Co and sent to the bus through A1. Since the resonant current itself is sinusoidal and will naturally pass through zero, the rectifier diode turns off when the current is zero (ZCS, zero-current turn-off), and the turn-off loss is very small and there is almost no reverse recovery spike.

[0074] The principle of the isolation DC / DC converter I for realizing power is as follows: The high-frequency square wave between A and B is not directly applied to the transformer, but first passes through a "resonant cavity" composed of three components: the resonant inductor Lr, the resonant capacitor Cr, and the transformer excitation inductor Lm.

[0075] The resonant cavity can be understood as a filter that is very picky about frequency: the square wave contains the fundamental wave and various harmonics, and the resonant cavity almost only allows the fundamental wave of this frequency to pass through smoothly and transmit power. As a result, the current flowing through the transformer becomes an approximately sinusoidal resonant current (instead of a square wave); the "amplification factor" (gain) of this filter changes with the switching frequency fs. There is a series resonant frequency fr = 1 / (2π·√(Lr·Cr)): when fs = fr, the gain ≈ 1, and the high-frequency alternating current on the secondary side is only determined by the turns ratio and is almost independent of the load. This is the "nominal operating point" with the highest efficiency; when fs < fr, the gain > 1, and the output is elevated (boost region); when fs > fr, the gain < 1, and the output is depressed (buck region). Therefore, as long as the control device changes the switching transistor frequency fs, it can change the gain of the resonant cavity, thereby continuously adjusting the output size of this branch.

[0076] Reference Figure 3 , the DC power receiving device includes a 48V DC input terminal, an input filter, and a controlled isolation DC / DC converter II.

[0077] Among them, the 48V DC input terminal, the input filter, and the controlled isolation DC / DC converter II are connected in sequence.

[0078] The 48V DC input terminal is connected to the energy storage battery of the photovoltaic power generation system to receive 48V DC power.

[0079] The 48V DC input terminal receives power from the energy storage battery and can introduce approximately 48V DC power (its voltage fluctuates between approximately 42V and 54V depending on the state of charge of the energy storage battery).

[0080] The input filter includes an input filter capacitor Cin; the first terminal of the input filter capacitor Cin is connected to the positive terminal of the 48V DC input terminal, and the second terminal of the input filter capacitor Cin is connected to the negative terminal of the 48V DC input terminal.

[0081] The input filter smooths current ripple on the energy storage battery side: During high-frequency switching, the controlled-isolation DC / DC converter II draws a pulsed high-frequency current from the input side. The input filter capacitor Cin provides this pulsed current nearby, ensuring the energy storage battery only needs to provide a smooth, average DC current. This reduces heat generation in the energy storage battery and its connecting cables, suppresses input voltage drops and spikes, and minimizes electromagnetic interference. The controlled-isolation DC / DC converter II also incorporates an input filter capacitor Cin with the same function.

[0082] The input filter capacitor Cin mainly smooths and decouples the DC output from the energy storage battery. However, the DC voltage of approximately 48V is relatively low at this point, and its power is difficult to control. Even after combining it with the common DC bus, it is still difficult to control its output ratio.

[0083] Therefore, a controlled isolated DC / DC converter II is needed to boost the approximately 48V DC power and convert it into approximately 310V DC power (i.e., a second DC load) with a controllable current.

[0084] The specific structure of the controlled isolated DC / DC converter II is described further below.

[0085] The controlled isolated DC / DC converter II includes: a second primary-side full bridge, a second isolation transformer, a second secondary-side rectifier bridge, and an output filter circuit.

[0086] The second primary-side full bridge includes switch Q5, switch Q6, switch Q7, and switch Q8; switch Q5 and switch Q6 form the second left bridge arm, and switch Q7 and switch Q8 form the second right bridge arm; the midpoints of the two bridge arms are denoted as node M and node N, respectively.

[0087] The second isolation transformer is used to achieve electrical isolation between the primary and secondary sides and to change the step-up ratio.

[0088] The second secondary rectifier bridge, including diodes D5, D6, D7, and D8, is used to rectify the high-frequency AC on the secondary side of the second isolation transformer into DC.

[0089] The output filter circuit, including the output inductor Lo and the second output capacitor Co2, is used to smooth the intermittent block voltage after rectification into a flat DC voltage; the output terminal of the controlled isolated DC / DC converter II is also connected in series with a current sensor A2 to detect the current of the second DC load.

[0090] The connection relationships of the controlled isolation DC / DC converter II are as follows: The first and second terminals of the input filter capacitor Cin serve as the positive and negative input terminals of the controlled isolated DC / DC converter II, respectively.

[0091] In the second primary-side full bridge: the first terminal of switch Q5 is connected to the positive input terminal, and the second terminal of switch Q5 is connected to node M; the first terminal of switch Q6 is connected to node M, and the second terminal of switch Q6 is connected to the negative input terminal; switches Q5 and Q6 are connected in series to form the second left bridge arm. The first terminal of switch Q7 is connected to the positive input terminal, and the second terminal of switch Q7 is connected to node N; the first terminal of switch Q8 is connected to node N, and the second terminal of switch Q8 is connected to the negative input terminal; switches Q7 and Q8 are connected in series to form the second right bridge arm.

[0092] The first end of the primary winding of the second isolation transformer is connected to node M, and the second end of the primary winding is connected to node N.

[0093] The first end of the secondary winding of the second isolation transformer is connected to the first AC input terminal of the second secondary rectifier bridge, and the second end of the secondary winding is connected to the second AC input terminal of the second secondary rectifier bridge; the positive DC output terminal of the second secondary rectifier bridge is denoted as node S, and the negative DC output terminal is denoted as node T.

[0094] In the second secondary rectifier bridge: the first end (anode) of diode D5 is connected to the first end of the secondary winding of the second isolation transformer, and the second end (cathode) of diode D5 is connected to node S; the first end of diode D6 is connected to the second end of the secondary winding of the second isolation transformer, and the second end of diode D6 is connected to node S; the first end of diode D7 is connected to node T, and the second end of diode D7 is connected to the first end of the secondary winding of the second isolation transformer; the first end of diode D8 is connected to node T, and the second end of diode D8 is connected to the second end of the secondary winding of the second isolation transformer.

[0095] In the output filter circuit: the first end of the output inductor Lo is connected to node S, and the second end of the output inductor Lo is denoted as node K; the first end of the second output capacitor Co2 is connected to node K, and the second end of the second output capacitor Co2 is connected to node T.

[0096] Current sensor A2 is connected in series between node K and the positive terminal of the common DC bus; node T is connected to the negative terminal of the common DC bus.

[0097] Controlled isolated DC / DC converter II is another power supply branch. Its input is approximately 48V DC from the energy storage battery, and its output needs to stably supply a controllable current (i.e., a second DC load) to the common DC bus. Due to the low input voltage, large boost ratio, and the fact that the energy storage battery voltage changes with the state of charge, a full-bridge boost topology with a second isolation transformer is selected here: the voltage is boosted by the turns ratio of the second isolation transformer, and the duty cycle (or phase shift angle) is used to adjust it at any time to adapt to changes in the energy storage battery voltage and stabilize the output.

[0098] The steps for power conversion using the controlled isolated DC / DC converter II are as follows: S1: Four switching transistors Q5 to Q8 work in turn to cut approximately 48V DC into high-frequency AC and apply it to the primary winding of the second isolation transformer; Specifically: Switches Q5 through Q8 operate alternately in a "diagonal conduction" manner. When switches Q5 and Q8 are simultaneously on, approximately 48V is applied to the primary winding via switch Q5 → node M → primary winding of the second isolation transformer → node N → switch Q8 (effective interval, energy is supplied to the secondary side). When switches Q5 and Q7 are simultaneously on, or switches Q6 and Q8 are simultaneously on, the primary winding is short-circuited, and the voltage across it is zero (freewheeling interval, no energy is supplied). When switches Q6 and Q7 are simultaneously on, a reverse voltage is applied to the primary winding. The proportion of the effective interval is the effective duty cycle D. By adjusting the duty cycle D (achieved by changing the phase shift angle between the two bridge arms in a phase-shifted full-bridge circuit), the energy transferred to the secondary side in each cycle can be changed.

[0099] S2: After the high-frequency AC is stepped up by the second isolation transformer, the stepped-up high-frequency AC is obtained on the secondary winding; S3: The high-frequency AC power on the secondary side is rectified by diodes D5 to D8: diodes D5 and D8 conduct during one half-cycle, and diodes D6 and D7 conduct during the other half-cycle, rectifying the AC power into pulsating DC power. This DC power is then filtered by the output inductor Lo and the second output capacitor Co2 to obtain approximately 310V of flat DC power, which is then sent to the common DC bus via the current sensor A2.

[0100] The principle of power generation by the controlled isolated DC / DC converter II is as follows: The approximately 48V DC is inverted into high-frequency AC by the second primary-side full-bridge inverter, then stepped up by the second isolation transformer at a turns ratio of 1:N, rectified, and then smoothed by the output inductor Lo and the second output capacitor Co2, thus raising the approximately 48V to the bus voltage level of approximately 310V.

[0101] The rectified voltage is a discontinuous block voltage "cut" out by the duty cycle. During the freewheeling phase, the output inductor Lo uses its stored energy to continue supplying power to the load via the second secondary rectifier bridge, ensuring a continuous output current in both the effective and freewheeling phases. The output inductor Lo and the second output capacitor Co2 together average the discontinuous block voltage into a smooth DC current. The averaging relationship is approximately Vo≈N·Vin·D (ignoring voltage drop), meaning the output voltage is proportional to the turns ratio, input voltage, and duty cycle. Therefore, the control device can continuously adjust the output current of this branch simply by changing the duty cycle D.

[0102] The current sensor A2 detects the output current (i.e., the second DC load) of the controlled isolated DC / DC converter II in real time and feeds it back to the control device. The control device adjusts the duty cycle D accordingly so that the second DC load accurately follows the second current reference given by the control device, thereby making the controlled isolated DC / DC converter II appear to the outside world as a controlled current source with controllable output current.

[0103] The turns ratio of the first and second isolation transformers is set according to the actual situation. The second isolation transformer receives a lower voltage (approximately 48V), so its turns ratio should be higher to facilitate voltage boosting. Conversely, the first isolation transformer receives a higher voltage (approximately 310V), so its turns ratio should be lower.

[0104] refer to Figure 4 The common DC bus includes the positive bus, the negative bus, the bus voltage stabilizing capacitor bank Cbus, the bus voltage sensor Vbus, and the bus current sensor A3.

[0105] The outputs of controlled isolated DC / DC converter I and controlled isolated DC / DC converter II are connected in parallel between the positive bus and the negative bus, and no isolation diodes are installed on the positive bus.

[0106] The connection relationships of the common DC bus are as follows: The positive rectified output terminal (node ​​G) of the controlled isolated DC / DC converter I is connected to the positive bus via current sensor A1, and the negative rectified output terminal (node ​​H) of the controlled isolated DC / DC converter I is connected to the negative bus; the positive output terminal (node ​​K) of the controlled isolated DC / DC converter II is connected to the positive bus via current sensor A2, and the negative rectified output terminal (node ​​T) of the controlled isolated DC / DC converter II is connected to the negative bus.

[0107] The first end of the bus voltage stabilizing capacitor bank Cbus is connected to the positive bus, and the second end is connected to the negative bus; the bus voltage sensor Vbus is connected between the positive bus and the negative bus to detect the bus voltage; the positive input terminal of the high voltage generator is connected to the positive bus via the bus current sensor A3, and the negative input terminal of the high voltage generator is connected to the negative bus.

[0108] The principle of a common DC bus is as follows: The common DC bus is used to receive the first DC load and the second DC load, and mixes the first DC load and the second DC load to generate a mixed DC load. Since there is no isolation diode on the positive bus, the controlled isolated DC / DC converter I and the controlled isolated DC / DC converter II are directly connected in parallel as two controlled current sources. The two currents are directly superimposed at the bus node according to Kirchhoff's current law, that is, the current of the mixed DC load is equal to the sum of the current of the first DC load and the current of the second DC load.

[0109] Because the bus consists of two controlled current sources connected in parallel, rather than mixed currents via an isolation diode, the problem of "the higher voltage source monopolizing power supply and the lower voltage source being reverse-cut off" will not occur. The two current sources of any proportion can coexist stably and be linearly superimposed on the bus, which is the physical basis for the realization of proportional mixed power supply.

[0110] The bus voltage stabilizing capacitor bank Cbus is used to stabilize the bus voltage, store energy, and absorb current fluctuations generated by the switching transistors of the two branches. When the output of any branch changes abruptly or a switching occurs, the bus voltage stabilizing capacitor bank Cbus can immediately support the bus voltage, preventing a significant drop in bus voltage and ensuring seamless switching between the two branches. The bus voltage sensor Vbus and the bus current sensor A3 respectively feed back the bus voltage and the current flowing to the high-voltage generator to the control device, serving as the basis for the control device to perform bus clamping and power distribution.

[0111] refer to Figure 5 The control device includes a central controller, a first gate drive circuit, a second gate drive circuit, a third gate drive circuit, and a signal sampling circuit.

[0112] The connection relationships of the control devices are as follows: The input of the first gate drive circuit is connected to the central controller, and the output of the first gate drive circuit is connected to the control terminals of switches Q1, Q2, Q3, and Q4 in the controlled isolated DC / DC converter I, respectively. The input of the second gate drive circuit is connected to the central controller, and the output of the second gate drive circuit is connected to the control terminals of switches Q5, Q6, Q7, and Q8 in the controlled isolated DC / DC converter II, respectively. The input of the third gate drive circuit is connected to the central controller, and the output of the third gate drive circuit is connected to the control terminals of the switches in the high voltage generator.

[0113] The input terminals of the signal sampling circuit are connected to current sensor A1, current sensor A2, bus current sensor A3, and bus voltage sensor Vbus, respectively. The output terminal of the signal sampling circuit is connected to the central controller. The central controller is also equipped with a power demand input terminal to receive the power demand provided by the user.

[0114] The principle of the control device is as follows: The control device uses dual closed-loop control to achieve power distribution, specifically including an inner loop and an outer loop.

[0115] The inner loop consists of constant current loops for each branch: Based on feedback from current sensor A1, the central controller changes the switching frequency fs of the controlled isolated DC / DC converter I via the first gate drive circuit, causing the current of the first DC load to follow the first current reference; based on feedback from current sensor A2, the central controller changes the duty cycle D of the controlled isolated DC / DC converter II via the second gate drive circuit, causing the current of the second DC load to follow the second current reference. Thus, the controlled isolated DC / DC converter I and the controlled isolated DC / DC converter II respectively function as controlled current sources with controllable output current.

[0116] The outer loop is the power distribution and bus clamping loop: The central controller obtains the total current reference based on the power demand provided by the user end, and determines the mixing ratio k of the first DC load and the second DC load based on the power supply margin of the photovoltaic power generation system and the power supply margin of the grid. According to this ratio, the total current reference is split into a first current reference (equal to k multiplied by the total current reference) and a second current reference (equal to 1 minus k multiplied by the total current reference). At the same time, the central controller adjusts the total current reference based on the feedback from the bus voltage sensor Vbus, clamping the bus voltage at approximately 310V, thus balancing the total output power of the two branches with the power drawn by the high-voltage generator.

[0117] Since no isolation diodes are installed on the common DC bus, the current of the mixed DC load is equal to the sum of the first DC load and the second DC load. The mixing ratio is entirely determined by the ratio of the first current reference to the second current reference, thus allowing for any continuous ratio between 0% and 100%, including: pure grid power supply (k=1, second current reference is zero), pure battery power supply (k=0, first current reference is zero), and a proportional mixture of both (0...). <k<1)。

[0118] When any branch (e.g., the power grid) experiences an anomaly, the central controller immediately transfers the current reference of that branch to the other branch. Since the two branches are always connected in parallel to a common DC bus and are both controlled current sources, the switching process does not require mechanical contacts or isolation diodes for commutation. With the support of the bus voltage stabilizing capacitor bank Cbus, seamless switching at the microsecond level can be achieved, and the bus voltage basically does not drop.

[0119] Furthermore, the hybridization ratio k can be dynamically determined by factors such as the state of charge (SOC) of the energy storage battery, time-of-use pricing, and the instantaneous output of the photovoltaic power generation system, thereby achieving intelligent energy management that reduces grid load while ensuring the total power required by the user. The specific setting method of the hybridization ratio can be selected according to the actual situation.

[0120] In addition, the central controller, based on the power demand provided by the user, controls the high-voltage generator via the third gate drive circuit to adjust the high-voltage electrical power applied to the electrodes of the electric stove, thereby regulating the flame intensity (plasma arc). The power demand provided by the user is essentially the flame intensity adjustment on the electric stove.

[0121] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A rectifier power supply system for a high-power electric stove, characterized in that, include: An AC power receiving device is used to receive AC power from the power grid and convert the AC power into a first DC load; A DC receiving device is used to receive DC power stored in a photovoltaic power generation system and convert the DC power into a second DC load. A common DC bus receives a first DC load and a second DC load, and mixes the first DC load and the second DC load to generate a mixed DC load. The high-voltage generator converts the mixed DC load into a high-voltage current and sends it to the electrodes of the electric stove to produce an open flame. The control device controls the size of the mixed load based on the power demand provided by the user, and controls the mixing ratio of the first DC load and the second DC load based on the power supply margin of the photovoltaic power generation system and the power supply margin of the power grid.

2. The rectifier power supply system for the high-power electric stove according to claim 1, characterized in that, The AC receiving device includes: The 220V AC input terminal is connected to the power grid to receive 220V AC power. EMI filter / rectifier bridge / filter capacitor converts 220V, 50Hz AC power into DC current; The controlled isolated DC / DC converter I converts DC current into a first DC load whose current magnitude can be controlled.

3. The rectifier power supply system for the high-power electric stove according to claim 2, characterized in that, The controlled isolated DC / DC converter I includes: The first primary-side full bridge includes switch Q1, switch Q2, switch Q3, and switch Q4. Switch Q1 and switch Q2 form the first left bridge arm, and switch Q3 and switch Q4 form the first right bridge arm. The midpoints of the two bridge arms are denoted as A and B, respectively. The LLC resonant cavity includes a resonant inductor Lr, a resonant capacitor Cr, and a transformer magnetizing inductor Lm. The first isolation transformer is used to achieve electrical isolation between the primary and secondary sides and to change the turns ratio. The first secondary rectifier bridge is connected to the first isolation transformer and is used to rectify high-frequency AC into DC. Wherein, the first end of the resonant inductor Lr is connected to node A, the second end of the resonant inductor Lr is connected to the first end of the resonant capacitor Cr; the second end of the resonant capacitor Cr is connected to the first end of the primary winding of the first isolation transformer; the second end of the primary winding of the first isolation transformer is connected to node B, and the magnetizing inductance Lm is the magnetizing inductance of the first isolation transformer itself, which is equivalent to being connected in parallel between the first end and the second end of the primary winding of the first isolation transformer.

4. The rectifier power supply system for the high-power electric stove according to claim 3, characterized in that, The controlled isolated DC / DC converter I also includes an output capacitor Co. The first end of the output capacitor Co is connected to the positive DC output terminal of the first secondary rectifier bridge, and the second end of the output capacitor Co is connected to the negative DC output terminal of the first secondary rectifier bridge.

5. The rectifier power supply system for the high-power electric stove according to claim 3, characterized in that, The control device controls the first DC load by controlling the switching transistors Q1 to Q4 to conduct at a frequency that is diagonally opposite.

6. The rectifier power supply system for the high-power electric stove according to claim 1, characterized in that, The DC receiving device includes: The 48V DC input terminal is connected to the energy storage battery of the photovoltaic power generation system to receive 48V DC power. Input filter, used to smooth current ripples on the energy storage battery side; The controlled isolated DC / DC converter II converts DC current into a second DC load whose current magnitude can be controlled.

7. The rectifier power supply system for the high-power electric stove according to claim 6, characterized in that, Controlled isolated DC / DC converter II includes: The second primary-side full bridge includes switch Q5, switch Q6, switch Q7, and switch Q8; switch Q5 and switch Q6 form the second left bridge arm, and switch Q7 and switch Q8 form the second right bridge arm; the midpoints of the two bridge arms are denoted as node M and node N, respectively. The second isolation transformer is used to achieve electrical isolation between the primary and secondary sides and to change the step-up ratio; The second auxiliary rectifier bridge is connected to the second isolation transformer and is used to rectify high-frequency AC into DC. The output filter circuit, including the output inductor Lo and the second output capacitor Co2, is used to smooth the intermittent block voltage after rectification into a straight DC to obtain the second DC load. Current sensor A2 is used to monitor the magnitude of the second DC load; Among them, the first end of the primary winding of the second isolation transformer is connected to node M, and the second end of the primary winding is connected to node N; The positive DC output terminal of the second secondary rectifier bridge is denoted as node S, and the negative DC output terminal of the second secondary rectifier bridge is denoted as node T. The first end of the output inductor Lo is connected to node S, and the second end of the output inductor Lo is denoted as node K; the first end of the second output capacitor Co2 is connected to node K, and the second end of the second output capacitor Co2 is connected to node T; the current sensor A2 is connected in series between node K and the positive terminal of the common DC bus; node T is connected to the negative terminal of the common DC bus.

8. The rectifier power supply system for the high-power electric stove according to claim 7, characterized in that, The common DC bus includes: positive bus, negative bus, and bus voltage regulator capacitor bank Cbus; No isolation diodes are installed on the positive busbar; The outputs of controlled isolated DC / DC converter I and controlled isolated DC / DC converter II are both connected in parallel between the positive bus and the negative bus; The first end of the bus voltage regulator capacitor bank Cbus is connected to the positive bus, and the second end is connected to the negative bus.

9. The rectifier power supply system for the high-power electric stove according to claim 7, characterized in that, Control device includes Central controller; The first gate drive circuit has its input terminal connected to the central controller and its output terminal connected to the control terminals of the switching transistors Q1, Q2, Q3, and Q4 in the controlled isolated DC / DC converter I. The second gate drive circuit has its input terminal connected to the central controller and its output terminal connected to the control terminals of switching transistors Q5, Q6, Q7, and Q8 in the controlled isolated DC / DC converter II, respectively. The third gate drive circuit has its input terminal connected to the central controller and its output terminal connected to the control terminal of the switching transistor in the high voltage generator. The signal sampling circuit is used to acquire data from the first DC load, the second DC load, and the mixed DC load. The central controller controls the opening and closing of switches Q1, Q2, Q3, Q4, Q5, Q6, Q7, and Q8 based on the sampling results from the signal sampling circuit.

10. The rectifier power supply system for the high-power electric stove according to claim 9, characterized in that, The control device uses dual closed-loop control to achieve power distribution, specifically including an inner loop and an outer loop; The inner loop is a constant current loop for each branch. The central controller controls the controlled isolated DC / DC converter I and the controlled isolated DC / DC converter II to output a controllable first load current and a second load current respectively. The outer ring is a power distribution and bus clamping ring. The central controller obtains the total current reference based on the power demand provided by the user end, and determines the mixing ratio k of the first DC load and the second DC load based on the power supply margin of the photovoltaic power generation system and the power supply margin of the grid. The first load current and the second load current are adjusted according to the mixing ratio k.

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