Inverter drive circuit based on isolation transformer and electric flame stove

Abstract

The invention discloses an inversion drive circuit based on an isolation transformer, which is used for an electric flame stove and comprises a direct-current power supply, a control module, an isolation drive module and an inversion module. The electrical isolation characteristics of the isolation transformers TR1 and TR2 can prevent the high voltage from being conducted to the control module, so that sensitive electronic elements in the control module are protected; the acceleration turn-off module can accelerate a parasitic capacitor in the transistor to release charges, so that alternating current output of the transistor is realized, and stable alternating current output is ensured. A resistor R9 is connected in series between the connection point of the drain electrode of the transistor Q1 and the drain electrode of the transistor Q2 and the positive electrode of the direct-current power supply, and as a series resistor, oscillation energy can be consumed and converted into heat energy, so that the oscillation amplitude and frequency are reduced, and the circuit is more stable. A 58V direct-current power supply is adopted, and even if certain voltage drop is generated through a line resistor, it can be guaranteed that a load end has enough voltage to work normally.

Description

Technical Field

[0001] The present invention particularly relates to the field of electric flame cookers. Background Art

[0002] The working principle of the electric flame stove is to generate plasma electric flame by outputting high voltage through a multi-channel capacitor circuit. For example, the patent with application number 2020110139181 proposes an electric flame circuit, including a rectifier filter circuit 10, an inverter circuit 20, a resonant boost circuit 30, a signal generator circuit 40 and a plurality of discharge point pairs connected in parallel; the inverter circuit 20 receives the square wave signal output by the signal generator circuit 40 and the DC power supply output by the rectifier filter circuit 10, and performs an inversion conversion on the DC power supply according to the square wave signal. The inverter circuit 20 can adopt a half-bridge inverter circuit 20 or a full-bridge inverter circuit 20, which has The inverter circuit 20 is configured according to the requirements. As shown in FIG5 , in one embodiment, the inverter circuit 20 includes an inverter bridge and a first transformer T1. The inverter bridge is electrically connected to the rectifier filter circuit 10, the signal generating circuit 40 and the first transformer T1 respectively. The inverter bridge is a half bridge, including a third switch tube Q3, a fourth switch tube Q4 and an eleventh capacitor C11 and a twelfth capacitor C12 connected in parallel. The inverter bridge and the first transformer T1 are used for inverter conversion. When driven by a square wave signal, a high-frequency square wave signal of 300V is output.

[0003] The inverter circuit in this patented technical solution converts direct current into high-frequency alternating current through the high-frequency driving signal provided by the signal generating circuit and outputs it to the resonant boost circuit. However, this solution has many defects in actual application: For example, in the actual circuit operation process, the circuit where the signal generating circuit is located may be a relatively low voltage, small current signal generating circuit, while the inverter circuit, because it involves the work of the power switch tube, may have high voltage and large current. When the switch tube in the inverter circuit is in a fast switching state, voltage spikes may be generated. These high voltages are likely to directly impact the signal generating circuit; For another example, when the switch tube is turned off, the charge stored in the parasitic capacitance of the switch tube gate needs to be discharged quickly to achieve fast shutdown. Otherwise, after the shutdown time becomes longer, the rising and falling edges of the output waveform will become flat, and the quality of the output waveform will decrease, which will have an adverse effect on the resonant boost circuit. In addition, although a filter capacitor is provided in the rectifier and filter circuit in the patent technical solution, for a high-frequency inverter circuit, voltage spikes are generated by the alternating on / off of the switch tube, and the circuit oscillation between the rectifier and filter circuit and the inverter circuit will also affect the voltage stability when the switch tube is turned on. Summary of the invention

[0004] In order to overcome the above-mentioned shortcomings, the present invention aims to provide a technical solution that can solve the above-mentioned problems.

[0005] An inverter drive circuit based on an isolation transformer, used for an electric flame cooker, characterized in that it comprises: a DC power supply, a control module, an isolation drive module and an inverter module; The inverter module is composed of transistors Q1, Q2, Q3, and Q4 connected in full bridge mode, and the isolation drive module includes isolation transformers TR1 and TR2; wherein, the two ends of the secondary coil S1 in the isolation transformer TR1 are respectively connected to the gate and source of the transistor Q1, the two ends of the secondary coil S2 in the isolation transformer TR2 are respectively connected to the gate and source of the transistor Q2, the two ends of the secondary coil S3 in the isolation transformer TR1 are respectively connected to the gate and source of the transistor Q3, and the two ends of the secondary coil S4 in the isolation transformer TR2 are respectively connected to the gate and source of the transistor Q4; Resistors R1, R2, R3, and R4 are respectively provided between the secondary coil S1 and the gate of the transistor Q1, between the secondary coil S2 and the gate of the transistor Q2, between the secondary coil S3 and the gate of the transistor Q3, and between the secondary coil S4 and the gate of the transistor Q4; Preferably, it further comprises an accelerated shutdown module, wherein the accelerated shutdown module comprises diodes D1, D2, D3, and D4, wherein the diodes D1, D2, D3, and D4 are respectively connected in parallel with the resistors R1, R2, R3, and R4; Preferably, the diodes D1, D2, D3, and D4 are also connected in series with resistors R5, R6, R7, and R8, respectively, and the resistors R5, R6, R7, and R8 are all low-resistance resistors; Preferably, a resistor R9 is connected in series between the connection point between the drain of the transistor Q1 and the drain of the transistor Q2 and the positive electrode of the DC power supply; Preferably, a filter capacitor C1 is connected in parallel between the connection point between the drain of the transistor Q1 and the drain of the transistor Q2 and the connection point between the source of the transistor Q3 and the source of the transistor Q3; Preferably, a filter capacitor C2 is connected in series between the connection point between the source of the transistor Q1 and the drain of the transistor Q3 and the AC power output terminal Vo1; Preferably, the connection point between the source of the transistor Q2 and the drain of the transistor Q4 is connected to the AC output terminal Vo2; Preferably, the primary coils of the isolation transformers TR1 and TR2 are respectively connected to the chip of the control module; Preferably, the voltage between the positive and negative electrodes of the DC power supply is 58V; The present invention further provides an electric flame cooker, which includes any one of the above-mentioned inverter drive circuits based on an isolation transformer.

[0006] Compared with the prior art, the advantages of the present invention are: The electrical isolation characteristics of the isolation transformers TR1 and TR2 of the present invention can prevent these high voltages from being conducted to the control module, thereby protecting sensitive electronic components in the control module; The accelerated shutdown module of the present invention can accelerate the release of charges from the parasitic capacitor inside the transistor, thereby realizing the alternating output current of the transistor and ensuring stable AC output; A resistor R9 is connected in series between the connection point of the drain of the transistor Q1 and the drain of the transistor Q2 of the present invention and the positive electrode of the DC power supply. As a series resistor, it can consume the oscillation energy and convert it into heat energy, thereby reducing the amplitude and frequency of the oscillation and making the circuit more stable. The present invention adopts a 58V DC power supply, and even if a certain voltage drop occurs through line resistance, it can ensure that the load end has sufficient voltage to work normally.

[0007] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0009] Figure 1 This is the schematic diagram of the overall circuit framework of the electric flame stove.

[0010] Figure 2 It is the principle diagram of the inverter drive circuit of the present invention. DETAILED DESCRIPTION

[0011] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0012] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limitations on the present invention.

[0013] In addition, in the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", etc. should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, it can also be the internal communication of two components, it can be a wireless connection, or it can be a wired connection. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0014] In addition, the technical features involved in the different embodiments of the present invention described later can be combined with each other as long as they do not conflict with each other.

[0015] See also Figure 1-2 In an embodiment of the present invention, an inverter drive circuit based on an isolation transformer is used for an electric flame cooker, comprising: a DC power supply 100, a control module 200, an isolation drive module 300 and an inverter module 500; like Figure 2 As shown, in this embodiment, the inverter module 500 is composed of transistors Q1, Q2, Q3, and Q4 connected in full bridge mode, and the isolation drive module 300 includes isolation transformers TR1 and TR2; wherein, the two ends of the secondary coil S1 in the isolation transformer TR1 are respectively connected to the gate and source of the transistor Q1, the two ends of the secondary coil S2 in the isolation transformer TR2 are respectively connected to the gate and source of the transistor Q2, the two ends of the secondary coil S3 in the isolation transformer TR1 are respectively connected to the gate and source of the transistor Q3, and the two ends of the secondary coil S4 in the isolation transformer TR2 are respectively connected to the gate and source of the transistor Q4; the same-name ends of the secondary coils S1 and S3 are opposite to those of the secondary coils S2 and S4.

[0016] Its working principle: When the driving signal generated by the control module 200 is input to the primary coil of the isolation transformer TR1, TR2, an alternating current will be generated in the primary coil. Since the secondary coils S1, S3 have opposite terminals to the secondary coils S2, S4, the transistors can be alternately turned on during the driving process.

[0017] like Figure 1-2As shown, for example, at a certain moment, the drive signal of the secondary coils S1 and S3 turns on Q1 and Q3. At this time, the current flows out from the positive pole of the DC power supply 100, passes through Q1, passes through the primary winding of the main boost circuit 600, and then returns to the negative pole of the DC power supply 100 through Q3. In this process, the voltage polarity on the primary winding of the main boost circuit 600 is positive, which is equivalent to the positive half cycle of the output AC power; as the drive signal changes, the induced voltage of the secondary coil of the isolation transformer changes, and the drive signal of the secondary coils S2 and S4 turns on Q2 and Q4. At this time, Q1 and Q3 are cut off, and the current flows out from the positive pole of the DC power supply 100, passes through Q4, passes through the primary winding of the main boost circuit 600 (the current direction is opposite to that before), and then returns to the negative pole of the DC power supply 100 through Q2. The voltage polarity on the primary winding of the main boost circuit 600 becomes negative, which is equivalent to the negative half cycle of the output AC power. By continuously driving the transistor alternately at a certain frequency and duty cycle, a stable AC power can be obtained at the primary winding end of the main boost circuit 600.

[0018] However, in this embodiment, since the inverter module 500 involves power conversion, a relatively high voltage may be generated. For example, when the transistors Q1 / Q3, Q2 / Q4 in the inverter circuit are in a fast switching state, voltage spikes may be generated, and these high voltages may directly impact the control module 200. The electrical isolation characteristics of the isolation transformers TR1 and TR2 can prevent these high voltages from being transmitted to the control module 200, thereby protecting the sensitive electronic components in the control module 200.

[0019] like Figure 2 As shown, in another embodiment of the present invention, resistors R1, R2, R3, and R4 are respectively arranged between the secondary coil S1 and the gate of the transistor Q1, between the secondary coil S2 and the gate of the transistor Q2, between the secondary coil S3 and the gate of the transistor Q3, and between the secondary coil S4 and the gate of the transistor Q4. When the voltage of the secondary coil of the isolation transformer changes suddenly or the gate capacitance of the transistor is charged, the current may rise sharply, thereby damaging the transistor. Specifically, taking the transistor Q1 as an example, when the voltage across the secondary coil S1 changes, if there is no resistor R1, a large current may flow directly into the gate of Q1. Assuming that the secondary coil of the isolation transformer outputs a pulse voltage with a high amplitude, this voltage is directly applied between the gate and the source of Q1. Due to the equivalent capacitance of the gate, a large charging current will be generated. After adding the resistor R1, the current size will be limited by the resistor R1, thereby avoiding excessive current from damaging the gate of the transistor Q1.

[0020] The inverter drive circuit based on the isolation transformer also includes an accelerated shutdown module 400, which includes diodes D1, D2, D3, and D4, wherein the diodes D1, D2, D3, and D4 are respectively connected in parallel with the resistors R1, R2, R3, and R4. When the transistors Q1, Q2, Q3, and Q4 are switched from the on state to the off state, the charge stored in the parasitic capacitance inside the transistor needs to be released as quickly as possible to achieve rapid shutdown.

[0021] The accelerated shutdown module 400 can accelerate the release of charges from the parasitic capacitance inside the transistor, thereby realizing the alternating output current of the transistor and ensuring stable AC output. Taking transistor Q1 as an example, when Q1 needs to be turned off, the charges accumulated in its gate parasitic capacitance need a fast discharge channel, and the diode D1 connected in parallel with the resistor R1 provides such a path, so that the charges can quickly flow out of the gate, thereby accelerating the shutdown speed of Q1.

[0022] In another embodiment, in order to prevent the diode from being damaged by excessive instantaneous current when the transistor is quickly turned off, the diodes D1, D2, D3, and D4 are respectively connected in series with resistors R5, R6, R7, and R8, and the resistors R5, R6, R7, and R8 are all low-resistance resistors.

[0023] The low-resistance resistors R5, R6, R7, and R8 can limit the current while allowing a sufficiently large current to pass to achieve rapid shutdown.

[0024] In the next embodiment, a resistor R9 is connected in series between the connection point of the drain of transistor Q1 and the drain of transistor Q2 and the positive electrode of the DC power supply 100. In a high-frequency inverter circuit, parasitic inductance and parasitic capacitance may cause oscillation. As a series resistor, resistor R9 can consume the oscillation energy and convert it into heat energy, thereby reducing the amplitude and frequency of the oscillation and making the circuit more stable.

[0025] In the next embodiment, a filter capacitor C1 is connected in parallel to the connection point between the drain of transistor Q1 and the drain of transistor Q2 and the connection point between the source of transistor Q3 and the source of transistor Q3. The filter capacitor C1 is equivalent to a temporary current source, which releases the stored charge and supplements the voltage at the moment when the transistor is turned on, indirectly promoting the rapid conduction of the transistor and achieving stable AC output.

[0026] In the next embodiment, a filter capacitor C2 is connected in series between the connection point of the source of transistor Q1 and the drain of transistor Q3 and the AC output terminal Vo1. The filter capacitor C2 mainly blocks DC power, ensuring that the signal output to Vo1 is mainly AC power, and ensuring the normal operation of the main boost circuit 600.

[0027] In the next embodiment, the connection point between the source of the transistor Q2 and the drain of the transistor Q4 is connected to the AC output terminal Vo2 . The AC output terminals Vo1 and Vo2 are electrically connected to the main boost circuit 600 .

[0028] In the next embodiment, the primary coils of the isolation transformers TR1 and TR2 are electrically connected to the chip of the control module 200 respectively.

[0029] In the next embodiment, the voltage between the positive and negative electrodes of the DC power supply 100 is 58V. If a conventional 48V DC power supply 100 is used, the voltage loss caused by the line resistance may cause the voltage actually obtained at the load end to be lower than the voltage required for the load to work normally. However, by using a 58V DC power supply 100, even if a certain voltage drop occurs through the line resistance, it can ensure that the load end has enough voltage to work normally, and the 58V DC power supply 100 can provide a wider input voltage range for these subsequent voltage regulation circuits, making the circuit design more flexible.

[0030] A DC power supply 100 with a higher voltage has higher requirements on the withstand voltage performance of each electronic component, which increases the cost. Therefore, a 58V DC power supply 100 is more suitable for the control module 200 and the drive inverter module 500 of the electric flame stove.

[0031] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

Claims

1. An inverter drive circuit based on an isolation transformer, used for an electric flame cooker, characterized in that: include: DC power supply, control module, isolation drive module and inverter module; The inverter module is composed of transistors Q1, Q2, Q3, and Q4 connected in full bridge mode, and the isolation drive module includes isolation transformers TR1 and TR2; wherein, the two ends of the secondary coil S1 in the isolation transformer TR1 are respectively connected to the gate and source of the transistor Q1, the two ends of the secondary coil S2 in the isolation transformer TR2 are respectively connected to the gate and source of the transistor Q2, the two ends of the secondary coil S3 in the isolation transformer TR1 are respectively connected to the gate and source of the transistor Q3, and the two ends of the secondary coil S4 in the isolation transformer TR2 are respectively connected to the gate and source of the transistor Q4; Resistors R1, R2, R3, and R4 are respectively provided between the secondary coil S1 and the gate of the transistor Q1, between the secondary coil S2 and the gate of the transistor Q2, between the secondary coil S3 and the gate of the transistor Q3, and between the secondary coil S4 and the gate of the transistor Q4.

2. The inverter drive circuit based on the isolation transformer according to claim 1, characterized in that: It also includes an accelerated shutdown module, which includes diodes D1, D2, D3, and D4, wherein the diodes D1, D2, D3, and D4 are respectively connected in parallel with the resistors R1, R2, R3, and R4.

3. The inverter drive circuit based on the isolation transformer according to claim 2, characterized in that: The diodes D1, D2, D3, and D4 are also connected in series with resistors R5, R6, R7, and R8, respectively. The resistors R5, R6, R7, and R8 are all low-resistance resistors.

4. The inverter drive circuit based on the isolation transformer according to claim 3, characterized in that: A resistor R9 is connected in series between the connection point between the drain of the transistor Q1 and the drain of the transistor Q2 and the positive electrode of the DC power supply.

5. The inverter drive circuit based on the isolation transformer according to claim 1, characterized in that: A filter capacitor C1 is connected in parallel to a connection point between the drain of the transistor Q1 and the drain of the transistor Q2 and a connection point between the source of the transistor Q3 and the source of the transistor Q3.

6. The inverter drive circuit based on the isolation transformer according to claim 1, characterized in that: A filter capacitor C2 is connected in series between the connection point between the source of the transistor Q1 and the drain of the transistor Q3 and the AC power output terminal Vo1.

7. The inverter drive circuit based on the isolation transformer according to claim 1, characterized in that: A connection point between the source of the transistor Q2 and the drain of the transistor Q4 is connected to the AC power output terminal Vo2.

8. The inverter drive circuit based on the isolation transformer according to claim 1, characterized in that: The primary coils of the isolation transformers TR1 and TR2 are respectively connected to the chips of the control module.

9. The inverter drive circuit based on the isolation transformer according to claim 1, characterized in that: The voltage between the positive and negative poles of the DC power supply is 58V.

10. An electric flame cooker, characterized in that: The electric flame cooker comprises an inverter drive circuit based on an isolation transformer as described in any one of claims 1 to 9.

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