A driving circuit, a two-transistor series topology and its application

Abstract

This invention discloses a driving circuit, a dual-transistor series topology, and its application. The driving circuit includes: first and second diodes, first and second capacitors, a first switch, and a control module. The anode of the first diode is the positive input terminal, and the cathode of the first diode is connected to both the anode of the second diode and one end of the first capacitor. One end of the first switch is the negative input terminal, and the other end of the first switch is connected to both the other end of the first capacitor and one end of the control module. The cathode of the second diode, when connected to one end of the second capacitor, is the positive output terminal, and the other end of the control module, when connected to the other end of the second capacitor, is the negative output terminal. The first switch operates in a chopping mode. When the first switch switches from on to off, or from off to on, the voltage across the control module reverses. This driving circuit can shift the voltage level to the high side and maintain continuous isolation output on the high side. It uses fewer circuit components, reducing the design difficulty of the driving circuit.

Description

Technical Field

[0001] This invention patent relates to the driving of switching transistors, and particularly to a driving circuit, a two-transistor series topology, and its applications. Background Technology

[0002] Conventional methods for driving switching transistors include using charge pump circuits, magnetic isolation drive technology, or driver ICs. A typical charge pump circuit is as follows: Figure 1 As shown, the capacitor bootstrap function is used to boost the output of the subsequent circuit, but the input and output share a common ground, which cannot meet the isolation requirements of the application. Existing magnetic isolation drive technology can achieve good isolation, but in order to avoid magnetic saturation, this technology cannot provide continuous drive and requires a drive transformer, increasing the circuit size. Existing driver IC solutions are usually suitable for dual-transistor series topologies. Typically, these ICs only support complementary drive signals. When the low-side switch of the dual-transistor series topology is turned on, the high-side switch is turned off, charging the bootstrap capacitor, which cannot keep the high-side switch in a constantly conducting state.

[0003] In summary, there is currently no continuous driving solution with isolation function for driving switching transistors. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to provide a driving circuit and its control method, which at least partially solves one of the technical problems existing in the prior art.

[0005] As a first aspect of the present invention, an embodiment of the driving circuit is provided as follows:

[0006] A driving circuit includes: a first diode, a second diode, a first capacitor, a second capacitor, a first switch, and a control module, as well as a positive signal input terminal, a negative signal input terminal, a positive signal output terminal, and a negative signal output terminal; the anode of the first diode serves as the positive signal input terminal, the cathode of the first diode is simultaneously connected to the anode of the second diode and one end of the first capacitor, one end of the first switch serves as the negative signal input terminal, the other end of the first switch is simultaneously connected to the other end of the first capacitor and one end of the control module, the cathode of the second diode and one end of the second capacitor are connected together to serve as the positive signal output terminal, and the other end of the control module and the other end of the second capacitor are connected together to serve as the negative signal output terminal; the first switch operates in a chopping manner; when the first switch switches from an on state to an off state, or from an off state to an on state, the voltage across the control module reverses.

[0007] One specific implementation of the control module is an inductor or a switching power supply.

[0008] Preferably, the first switch is any controllable switching device with switching characteristics, such as a MOSFET or a transistor.

[0009] As a second aspect of the present invention, an embodiment of the provided dual-tube series topology is as follows:

[0010] A dual-transistor series topology, the main power circuit of which includes: a first main power switch, a second main power switch, a main power inductor, and a driving circuit as described in any of the first aspects above, as well as a positive power supply voltage input terminal and a negative power supply voltage input terminal; one end of the first main power switch serves as the positive power supply voltage input terminal, the other end of the first main power switch is connected to one end of the main power inductor, the other end of the main power inductor is connected to one end of the second main power switch, the other end of the second main power switch serves as the negative power supply voltage input terminal, the positive signal output terminal is connected to the control terminal of the first main power switch, and the negative signal output terminal is connected to the other end of the first main power switch.

[0011] Furthermore, the main power inductor and the control module are reused.

[0012] Furthermore, the second main power switch and the first switch are multiplexed.

[0013] As a third aspect of the present invention, an embodiment of the provided switching power supply is as follows:

[0014] A switching power supply comprising an embodiment of the dual-transistor series topology described in any of the preceding claims.

[0015] As a fourth aspect of the present invention, an embodiment of the contactor energy-saving control circuit is provided as follows:

[0016] A contactor energy-saving control circuit includes an embodiment of the dual-tube series topology described in any of the preceding claims.

[0017] Compared with the prior art, the driving circuit of the present invention can produce the following beneficial effects:

[0018] (1) Compared with existing conventional charge pump circuits, its drive output and input are not grounded, which can meet the requirements of isolated drive;

[0019] (2) Compared with the existing magnetic isolation drive technology, it reduces the number of drive transformers, uses fewer components, and has a simpler control strategy;

[0020] (3) Compared with the existing driver ICs that drive the high side, the high side drive signal is relatively independent and is not affected by the low side drive. It can drive the output continuously at 0Hz. Specifically, the low side switch in the dual-transistor series topology will have a change in duty cycle due to load changes. The drive circuit of this invention is completely independent of the low side switch. When the load changes, the low side switch can be chopper switched normally. Regardless of whether the duty cycle is close to 100% or close to 0%, the drive output is not affected by its duty cycle and can drive continuously.

[0021] (4) The input and output are isolated by the first switch, and the size of the bootstrap floating ground voltage can be flexibly set by the control module;

[0022] (5) The input voltage VIN at the positive terminal of the signal input can be reused with the auxiliary power supply voltage VCC in the circuit system to which the drive circuit is used, without the need for an additional auxiliary power supply.

[0023] (6) The circuit is simple, the components are universally selected, the control is isolated, the cost is low, and the operation is easy;

[0024] (7) The main power inductor and control module are reused, and / or the second main power switch and the first switch are reused, further simplifying the complexity of the drive circuit application. Attached Figure Description

[0025] Figure 1 This is a circuit diagram for a conventional charge pump.

[0026] Figure 2 This is a schematic diagram of the driving circuit of the present invention;

[0027] Figure 3 This is a specific circuit diagram of the driving circuit of the present invention;

[0028] Figure 4 for Figure 3 Schematic diagram of a driver circuit applied to a two-transistor series topology; Detailed Implementation

[0029] The technical concept of this invention originates from the specific implementation and optimization design of the high-side switch driving based on the existing dual-transistor series application topology. It solves the technical problem of the floating switch maintaining constant conduction. Specifically, the switch is used as a trigger switch to continue maintaining the driving voltage, and devices with reverse voltage across the inductor are used as control modules. Combined with the energy transfer characteristics of the charge pump, it realizes isolated driving while continuously driving the high-side switch.

[0030] The circuit of the present invention will be described below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the circuit of the present invention.

[0031] Figure 2 Please refer to the schematic diagram of the driving circuit of this invention. Figure 2 The driving circuit includes: a first diode D1, a second diode D2, a first capacitor C1, a second capacitor C2, a first switch SW1, and a control module 101, as well as a positive signal input terminal VIN, a negative signal input terminal GND, a positive signal output terminal VO+, and a negative signal output terminal VO-. The anode of the first diode D1 serves as the positive signal input terminal VIN, and the cathode of the first diode D1 is connected to both the anode of the second diode D2 and one end of the first capacitor C1. One end of the first switch SW1 serves as the negative signal input terminal GND, and the other end of the first switch SW1 is connected to both the other end of the first capacitor C1 and one end of the control module 101. The cathode of the second diode D2 and one end of the second capacitor C2 are connected together to serve as the positive signal output terminal VO+, and the other end of the control module 101 and the other end of the second capacitor C2 are connected together to serve as the negative signal output terminal VO-. The first switch SW1 operates in a chopping manner. When the first switch SW1 switches from the on state to the off state, or from the off state to the on state, the voltage across the control module 101 reverses.

[0032] from Figure 2 As can be seen, compared with the existing conventional charge pump circuit, the drive circuit of the present invention has a drive output and input that are not grounded, which can meet the requirements of isolated drive; compared with the existing magnetic isolation drive technology, it reduces the drive transformer, uses fewer components, and has a simpler control strategy.

[0033] Figure 3 This is a specific circuit diagram of the driving circuit of the present invention, wherein the control module 101 is an inductor L1. Due to the continuous current characteristic in the inductor, when the first switch SW1 switches from the on state to the off state, or from the off state to the on state, a reverse electromotive force will be generated across the inductor L1, and the voltage across its terminals will be reversed.

[0034] As another specific implementation of the control module 101, it can also be a switching power supply. In this case, the switching power supply has the capability that the voltage across the switching power supply will reverse when the first switch SW1 switches from the on state to the off state, or from the off state to the on state.

[0035] The first switch SW1 can be any controllable switching device with switching characteristics, such as a MOSFET or a transistor. The control requirement is that the first switch SW1 operates in a chopping manner, that is, the signal controlling the first switch SW1 to turn on or off has high and low level changes, including but not limited to PWM waves, PFM waves, etc., so the first switch SW1 will have states such as on, switching from on to off, off, or switching from off to on.

[0036] Figure 4 for Figure 3 Please refer to the schematic diagram of the driver circuit applied to the two-transistor series topology. Figure 4 The main power circuit of the dual-transistor series topology includes: a first main power switch TR1, a second main power switch SW1, a main power inductor L1, and... Figure 3 The driving circuit in the circuit includes a positive power supply voltage input terminal Vg and a negative power supply voltage input terminal GND. One end of the first main power switch transistor TR1 serves as the positive power supply voltage input terminal Vg, and the other end of the first main power switch transistor TR1 is connected to one end of the main power inductor L1. The other end of the main power inductor L1 is connected to one end of the second main power switch transistor SW1, and the other end of the second main power switch transistor SW1 serves as the negative power supply voltage input terminal GND. The positive signal output terminal VO+ is connected to the control terminal of the first main power switch transistor TR1, and the negative signal output terminal VO- is connected to the other end of the first main power switch transistor TR1.

[0037] The main power inductor L1 and the control module are reused.

[0038] Furthermore, the second main power switch SW1 is multiplexed with the first switch.

[0039] The following is combined Figure 4 The working principle of the driving circuit of this invention is analyzed as follows:

[0040] The second main power switch SW1 operates in a chopper mode. When it is first turned on, VIN can charge the first capacitor C1 through the loop formed by the first diode D1, the first capacitor C1, the second main power switch SW1, and ground. At this time, since the drive voltage of the first main power switch TR1 is zero, the first main power switch TR1 is turned off, and no current flows through the main power loop. VIN will also charge the second capacitor C2 through the loop formed by the first diode D1, the second diode D2, the second capacitor C2, the main power inductor L1, the second main power switch SW1, and ground. Subsequently, when the voltage on the second capacitor C2 reaches the conduction threshold of the first main power switch TR1, the first main power switch TR1 gradually turns on, and the potential of the node connected to the second capacitor C2 and the main power inductor L1 will rise to Vg. VIN can no longer directly charge the second capacitor C2. At this time, the second capacitor C2 keeps the first main power switch TR1 on, and its voltage will gradually decrease. In order to replenish the energy of the second capacitor C2 in time, the second main power switch SW1 needs to be turned off. The node connected to the main power inductor L1 and the second main power switch SW1 will be momentarily induced with a high voltage. The voltage across the first capacitor C1 will not change abruptly, raising the node connected to the anode of the first capacitor C1 and the second diode D2 to a high voltage, causing the second diode D2 to conduct. The first capacitor C1 charges the second capacitor C2 through the second diode D2 and the main power inductor L1, maintaining the conduction state of the switch TR1.

[0041] When the second main power switch SW1 is turned on again, the potential of the first capacitor C1 will be pulled back to ground, so that VIN can be charged through diode D1 and switch SW1, thus preparing energy reserves for driving the output.

[0042] From the above analysis of the working principle, it can be seen that compared with existing driver ICs that perform high-side driving (driving high-side switching transistors, for example...) Figure 4 The first main power switch (TR1) in the dual-transistor series topology has a relatively independent high-side drive signal, unaffected by the low-side drive, which can shift the level to the high side to continuously isolate the output drive signal at 0Hz. Specifically, the low-side switch in the dual-transistor series topology (i.e., Figure 4 The second main power switch (SW1) in the circuit will have a change in duty cycle due to load changes. The drive circuit of this invention is completely independent of the low-side switch. When the load changes, the low-side switch can be normally chopper switched. Regardless of whether the duty cycle is close to 100% or close to 0%, the drive output is not affected by its duty cycle and can be continuously driven directly.

[0043] In addition, the driving circuit of the present invention has a series of other advantages, such as: the input and output are isolated by the first switch, the bootstrap floating ground voltage can be flexibly set by the control module; the input voltage VIN at the positive terminal of the signal input can be multiplexed with the auxiliary power supply voltage VCC in the circuit system in which the driving circuit is applied, without the need for an additional auxiliary power supply; the circuit is simple, the components are universally selected, the control is isolated, the cost is low, and it is easy to operate; the main power inductor and the control module are multiplexed, and / or the second main power switch and the first switch are multiplexed, further simplifying the complexity of the driving circuit application.

[0044] This invention also provides Figure 4 Applications of the two-tube series topology include, but are not limited to:

[0045] (1) Switching power supply. In this application scenario, the circuit topology used in the switching power supply is as follows: Figure 4 The dual-transistor series topology shown can also be applied to any topology that requires high-side drive for constant-on applications. The advantages of the drive circuit of this invention can be demonstrated when the main power switch is located on the high side. The main power switch being located on the high side means that it is located in the line between the positive terminal of the power supply voltage input Vg and one end of the main power inductor L1, that is, the main power switch needs to be driven by floating ground.

[0046] (2) Contactor energy-saving control circuit. This circuit is used to control the contactor coil and iron core's energizing state. At this time, the main power inductor L1 is the contactor coil. The first main power switch TR1 needs to be kept constantly on, requiring the drive circuit to continuously provide drive. Specifically: when the contactor is in the energizing stage, a large energizing current needs to pass through the coil to generate a sufficiently large electromagnetic force to make the contactor contacts energize; when the contactor is in the holding stage, a smaller energizing current passes through the coil to maintain the contactor's energizing state. The purpose of requiring a smaller energizing current in the coil is to minimize coil losses as much as possible.

[0047] The above are merely preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be considered as limitations on the present invention, and it should be understood that the present invention can be applied to other, more extensive scopes. Based on the above description of the present invention, and utilizing ordinary technical knowledge and conventional methods in the art, the present invention can be modified, replaced, or altered in various other forms without departing from the basic technical concept described above. For example, the switching transistor TR2 in the first embodiment can be replaced with any controllable switching device operating in a switching state, such as a transistor, and the inductor L1 can be replaced with a module power supply, etc. These modifications, replacements, or alterations all fall within the scope of protection of the present invention.

Claims

1. A driving circuit applied to a first main power switch tube in a double-tube series topology, one end of the first main power switch tube serving as a power voltage input positive terminal, characterized in that, include: The system comprises a first diode, a second diode, a first capacitor, a second capacitor, a first switch, and a control module, as well as a positive signal input terminal, a negative signal input terminal, a positive signal output terminal, and a negative signal output terminal. The anode of the first diode serves as the positive signal input terminal. The cathode of the first diode is simultaneously connected to the anode of the second diode and one end of the first capacitor. One end of the first switch serves as the negative signal input terminal. The other end of the first switch is simultaneously connected to the other end of the first capacitor and one end of the control module. The cathode of the second diode and one end of the second capacitor are connected together to serve as the positive signal output terminal, used to connect to the control terminal of the first main power switch. The other end of the control module and the other end of the second capacitor are connected together to serve as the negative signal output terminal, used to connect to the other end of the first main power switch. The first switch operates in a chopping manner. When the first switch is switched from the on state to the off state, or from the off state to the on state, the voltage across the control module will reverse.

2. The driving circuit according to claim 1, characterized in that: The control module is an inductor or a switching power supply.

3. The driving circuit according to claim 1, characterized in that: The first switch is a controllable switching device with switching characteristics.

4. A two-tube series topology, characterized in that, Its main power circuit includes: a first main power switch, a second main power switch, a main power inductor, and the driving circuit according to any one of claims 1 to 3, as well as a positive power supply voltage input terminal and a negative power supply voltage input terminal; one end of the first main power switch serves as the positive power supply voltage input terminal, the other end of the first main power switch is connected to one end of the main power inductor, the other end of the main power inductor is connected to one end of the second main power switch, the other end of the second main power switch serves as the negative power supply voltage input terminal, the positive signal output terminal is connected to the control terminal of the first main power switch, and the negative signal output terminal is connected to the other end of the first main power switch; the main power inductor and the control module are multiplexed; the second main power switch and the first switch are multiplexed.

5. A switching power supply, characterized in that: Includes the dual-tube series topology as described in claim 4.

6. A contactor energy-saving control circuit, characterized in that: Includes the dual-tube series topology as described in claim 4.

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