CN209994580U

CN209994580U - Peak voltage eliminating circuit

Info

Publication number: CN209994580U
Application number: CN201920002375.XU
Authority: CN
Inventors: 周林; 熊爱明
Original assignee: Jiaxing Super Lighting Electric Appliance Co Ltd
Current assignee: Jiaxing Super Lighting Electric Appliance Co Ltd
Priority date: 2018-05-30
Filing date: 2019-01-02
Publication date: 2020-01-24
Anticipated expiration: 2029-01-02

Abstract

The utility model provides a peak voltage cancelling circuit, including be used for generating first output signal's sampling module based on a voltage signal, be used for with first output signal and a reference voltage signal are compared and are exported the signal processing module of a comparative result signal, be used for according to the comparative result signal switches on and makes voltage signal's current flows through the switch module of a shunt circuit and is used for control the timing module of switch module's on-time. The peak voltage elimination circuit can reduce or eliminate peak voltage on components of the circuit.

Description

Peak voltage eliminating circuit

Technical Field

The utility model relates to an electricity field especially relates to a peak voltage elimination circuit.

Background

In dc circuits, especially inductive circuits, sudden connection of the circuit or sudden connection of a load can cause a voltage spike in the circuit, which can cause impact or damage to components and loads in the circuit.

For example, when an LED (Light Emitting Diode) lamp is connected to an inductive ballast, since the LED lamp needs a certain starting time, the inductive ballast is equivalent to no load during the starting time, so that the voltage at the output end of the inductive ballast gradually increases before the output end is connected to a load, and when an LED driving circuit in the LED lamp starts to operate, the inductive ballast outputs a peak voltage, which causes components in the driving circuit to bear a larger voltage, thereby shortening the service life of the lamp. FIG. 1 shows an input voltage V of a conventional LED driving circuit_inAnd LED drive current I_LEDThe waveform of (2). As shown in FIG. 1, for a certain LED lamp tube, the start-up of the LED driving circuit therein requires a certain time t_on. Over time, the input voltage V of the LED drive circuit_inGradually rises, then the LED drive circuit works normally and outputs a drive current I_LEDTo drive the LED to emit light, at which time the input voltage V_inA spike voltage is formed, and the peak value of the spike voltage is up to 551V. However, there is almost no electrolytic capacitor capable of withstanding high voltage of more than 500V and suitable for high temperature and large ripple condition in the market.

SUMMERY OF THE UTILITY MODEL

To the problem among the prior art, the utility model provides a peak voltage elimination circuit.

An embodiment of the utility model provides a peak voltage elimination circuit, peak voltage elimination circuit includes: the sampling module is used for sampling a voltage signal and generating a first output signal based on the voltage signal; the signal processing module is coupled to the sampling module and used for comparing the first output signal with a reference voltage signal and outputting a comparison result signal; the switch module is coupled to the signal processing module and used for enabling the current of the voltage signal to flow through a shunt circuit according to the conduction of the comparison result signal; and the timing module is coupled with the signal processing module and used for controlling the conduction time of the switch module. In an embodiment of the present invention, the shunt circuit includes a shunt resistor, a first end of the shunt resistor is used for receiving the voltage signal, and a second end of the shunt resistor passes through the switch module and connects to the ground potential.

In an embodiment of the present invention, the shunt circuit includes a shunt capacitor, a first end of the shunt capacitor is used for receiving the voltage signal, and a second end of the shunt capacitor passes through the switch module and connects to the ground potential.

In an embodiment of the present invention, the shunt circuit includes an LED group and a transistor; the anode of the LED group is used for receiving the voltage signal, and the cathode of the LED group is connected with one end of the transistor; the other end of the transistor is connected with the ground potential, and the control end of the transistor is turned on or off in response to a starting signal, so that the LED group emits light or stops emitting light; the cathode of the LED group is further coupled with the switch module.

In an embodiment of the present invention, the shunt circuit includes an LED group and an LED driving circuit; the LED driving circuit is used for receiving the voltage signal and driving the LED group to emit light; one end of the switch module is coupled to the cathode of the LED group, the other end of the switch module is connected to a ground potential, and the control end of the switch module is responsive to the comparison result signal to turn on the switch module to enable the current of the voltage signal to flow through the shunt circuit.

In an embodiment of the present invention, the switch module includes a switch transistor, one end of the switch transistor is coupled to the cathode of the LED set, the other end of the switch transistor is connected to the ground potential, and the control end of the switch transistor is coupled to the output end of the signal processing module.

In an embodiment of the present invention, the switch transistor is coupled to the cathode of the LED set through a first diode.

In an embodiment of the present invention, the LED driving circuit includes a voltage-reducing conversion circuit, and the driving inductor in the voltage-reducing conversion circuit is connected in series with the LED group and the switch module.

In an embodiment of the present invention, the power supply further includes an auxiliary circuit, wherein the auxiliary circuit includes a boost converter circuit; the input end of the auxiliary circuit is used for receiving a voltage signal from a rectifying circuit, and the output end of the auxiliary circuit is coupled to the input end of the buck conversion circuit so as to provide the voltage signal for the buck conversion circuit.

In an embodiment of the present invention, the LED driving circuit includes a boost converter circuit, and the driving inductor in the boost converter circuit is connected in series with the LED group and the switch module.

In an embodiment of the present invention, the peak voltage cancellation circuit further includes an auxiliary circuit and an LED driving circuit, and the auxiliary circuit includes a boost converter circuit; the LED driving circuit comprises a flyback circuit; the input end of the auxiliary circuit is used for receiving a voltage signal from a rectifying circuit, and the output end of the auxiliary circuit is coupled to the input end of the flyback circuit so as to provide the voltage signal for the flyback circuit.

In an embodiment of the present invention, the peak voltage eliminating circuit further includes a LED driving circuit, one end of the shunt circuit is coupled to the output end of the LED driving circuit, and the other end of the shunt circuit is coupled to the switch module.

In an embodiment of the present invention, the shunt circuit includes a shunt resistor, one end of the shunt resistor is coupled to the input terminal of the LED driving circuit, and the other end of the shunt resistor is coupled to the switch module.

In an embodiment of the present invention, the signal processing module includes a hysteresis voltage comparator.

In an embodiment of the present invention, the timing module includes a transistor, one end of the transistor is coupled to the input terminal of the signal processing module, the other end of the transistor is connected to the ground potential, and the control terminal of the transistor is coupled to one end of a capacitor; the other end of the capacitor is connected with the ground potential.

In an embodiment of the present invention, when the voltage at the two ends of the capacitor is increased to the threshold voltage of the transistor, the transistor is turned on, so that the input end of the signal processing module is grounded via the transistor.

In an embodiment of the present invention, the switch module includes a relay.

In an embodiment of the invention, the sampling module is configured to receive the voltage signal and send the first output signal to the signal processing module in response to the voltage signal.

In an embodiment of the present invention, the sampling module includes at least two resistors connected in series.

The utility model provides a peak voltage elimination circuit samples voltage signal, will when voltage signal is too high voltage signal adds in shunt circuit's one end or both ends, utilizes the shunt circuit to reduce or eliminate the peak voltage on circuit's the components and parts when peak voltage appears in the circuit, and then reduces the voltage stress that relevant component received in the circuit.

Drawings

Other features, objects and advantages of the invention will become more apparent from a reading of the following detailed description of non-limiting embodiments thereof, with reference to the accompanying drawings.

FIG. 1 shows an input voltage V of a conventional LED driving circuit_inAnd LED drive current I_LEDThe waveform of (a);

fig. 2 is a circuit block diagram of a peak voltage cancellation circuit according to an embodiment of the present invention;

fig. 3 is a circuit block diagram of a peak voltage cancellation circuit according to an embodiment of the present invention;

fig. 4 is a circuit block diagram of a peak voltage cancellation circuit according to an embodiment of the present invention;

fig. 5 is a circuit block diagram of a peak voltage cancellation circuit according to an embodiment of the present invention;

fig. 6 is a block circuit diagram of an embodiment of the present invention;

fig. 7 is a block circuit diagram of an embodiment of the present invention;

fig. 8 is a block circuit diagram of an embodiment of the present invention;

fig. 9 is a block circuit diagram of an embodiment of the present invention;

fig. 10 is a block circuit diagram of an embodiment of the present invention;

fig. 11 is a circuit diagram of a peak voltage cancellation circuit according to an embodiment of the present invention;

fig. 12 is a circuit diagram of a spike voltage cancellation circuit according to an embodiment of the present invention;

fig. 13 is a circuit diagram of a spike voltage cancellation circuit according to an embodiment of the present invention;

fig. 14 is a circuit diagram of a spike voltage cancellation circuit according to another embodiment of the present invention;

fig. 15 is a circuit diagram of an embodiment of the present invention, including a spike voltage cancellation circuit;

fig. 16 is a circuit diagram of an embodiment of the present invention, including a spike voltage cancellation circuit;

fig. 17 shows an input voltage V of an LED driving circuit according to an embodiment of the present invention_inAnd LED drive current I_LEDThe waveform of (a);

fig. 18 shows an input voltage V of an LED driving circuit according to an embodiment of the present invention_inLED drive current I_LEDAnd a driving voltage V of a switching transistor of the peak voltage cancel circuit_Q3The waveform of (2).

Detailed Description

In the description of the present invention, the terms "first", "second", etc. are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. Thus, a feature defined as "first," "second," etc. may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically limited otherwise. Where certain terms are used in the description and claims to refer to particular components, those skilled in the art will understand that different terms may be used to refer to the same component. This specification and claims do not intend to distinguish between components that differ in name but not function. The terms "including" and "comprising" as used throughout this specification and claims are open-ended terms that should be interpreted to mean "including, but not limited to. Further, the term "coupled" is intended to include any direct or indirect electrical connection. The specific meaning of the above terms in the present invention can be understood according to specific situations by those skilled in the art.

Example embodiments will now be described more fully with reference to the accompanying drawings. Example embodiments may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of example embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and thus their repetitive description will be omitted.

Fig. 2 is a circuit block diagram of a peak voltage cancellation circuit according to an embodiment of the present invention. As shown in fig. 2, in the present embodiment, the spike voltage elimination circuit includes a sampling module 10, a signal processing module 20, a switching module 30, a shunt circuit 40, and a timing module 50. The input voltage of the operating circuit 60 is V_inInput voltage V_inIs provided by an external power supply circuit. The sampling module 10 is configured to receive an input voltage V_inAnd in response to the input voltage V_inThe first output signal is sent to the signal processing module 20. The signal processing module 20 controls the switch module 30 to be turned on or off in response to the first output signal. When the switch module 30 is turned on, one end of the shunt circuit 40 receives the input voltage V_inThe other end is connected with the ground potential through a switch module 30, and the input voltage V is at the moment_inPower is supplied to both the shunt circuit 40 and the operation circuit 60. At this time, the operation circuit 60 has not yet started operating. Here, when the shunt circuit 40 operates, the shunt circuit 40 is used to shunt the current in the operating circuit 60, thereby reducing the currentThe spike voltage that may occur across the operational circuitry 60 is reduced or eliminated.

The timing module 50 is coupled to the signal processing module 20, and the timing module 50 is configured to control the output signal of the signal processing module 20 to control the conduction time of the switch module 30, so as to prevent the switch module 30 or components in the shunt circuit 40 from being damaged due to continuous conduction. In some embodiments, since the timing module 50 is configured to control the conduction time of the switch module 30, the operating circuit 60 delays a start time t after the switch module 30 is turned on_onThen, the operation is started, and then the timing module 50 controls the switch module 30 to be switched off.

In some embodiments, the input voltage V_inProvided by an inductive power supply circuit (e.g., a circuit including an inductive element such as an inductive ballast, not shown). After the power supply circuit is externally connected with the power supply, the working circuit 60 delays the starting time t_onAnd then starts working. If the shunt circuit 40 is not connected all the time, at the starting time t_onDuring which the supply circuit behaves like a dead load, before the supply circuit supplies a voltage to the load, the input voltage V_inIt will gradually increase. At this time, when the operation circuit 60 starts to operate, the input voltage V_inA peak voltage occurs, and at this time, the components of the operating circuit 60 are subjected to a large voltage stress. Therefore, if the shunt circuit 40 is activated at the time t_onThe period is connected to the circuit, and the input voltage V output by the power supply circuit is connected due to the load of the power supply circuit_inWill not rise further, so the input voltage V_inThe voltage spike is reduced or eliminated and the voltage stress experienced by the components in the operating circuit 60 is reduced.

In some embodiments, fig. 3 is a circuit block diagram of a spike voltage cancellation circuit according to an embodiment of the present invention. As shown in FIG. 3, the shunt circuit 40 has a first terminal for receiving the input voltage V_inA second terminal coupled to the shunt resistor R of the switch module 30_LWhen the switch module 30 is turned on in response to the output signal of the signal processing module 20, the shunt resistor R_LIs connected to ground potential via the switch module 30.

In some embodiments, FIG. 4 is a drawing of this documentUtility model a circuit block diagram of peak voltage elimination circuit of one embodiment. As shown in FIG. 4, the shunt circuit 40 has a first terminal for receiving the input voltage V_inAnd the other end is coupled with a shunt capacitor C of the switch module 30_LWhen the switch module 30 is turned on in response to the output signal of the signal processing module 20, the shunt capacitor C_LConnected to ground potential via a switch module 30. Therefore, in the shunt capacitance C_LThe voltage at both ends reaches the input voltage V_inBefore (ignoring the voltage across the switch module 30), the current flowing through the shunt capacitor CL will be given to the shunt capacitor C_LAnd charging is carried out.

Fig. 5 is a circuit block diagram of a peak voltage cancellation circuit according to an embodiment of the present invention. In the present embodiment, some devices in the shunt circuit 40 are also in the operating circuit 60. As shown in FIG. 5, the operating circuit 60 includes an LED₁To the LED_nA composed LED group, further comprising a transistor (transistor) Q for energizing the LED group₂(also referred to as a start-up transistor). Wherein the LED₁To the LED_nAre sequentially connected in series, and the anodes of the LED groups are used for receiving an input voltage V_inCathode connected start transistor Q₂One terminal of (1), starting the transistor Q₂And the other end of the second switch is connected to ground potential. Starting transistor Q₂In response to the start signal V_SWTo turn on or off to illuminate or stop illuminating the LED group.

At this time, the cathode of the LED set is further coupled to the switch module 30. When the switch module 30 is turned on, the LED group is connected to the ground potential through the switch module 30 and is supplied with the input voltage V_inDriven to emit light. The LEDs in the LED group may be connected in a plurality of ways, such as being connected in series, connected in parallel, or connected in series and then connected in parallel with other LEDs. Of course, those skilled in the art should understand that the connection method of the LED described above is only an example, and other existing connection methods, such as those applicable to the present invention, are also included in the protection scope of the present invention. For example, in the LED group, some LEDs are connected in parallel and then connected in series with other LEDs.

In some embodiments, the spike voltage disappearsThe neutralization circuit is used in an LED lighting fixture, for example, the spike voltage neutralization circuit is disposed in an LED lamp tube. As shown in fig. 6, the LED lighting fixture is powered by an external Alternating Current (AC) voltage (e.g., mains). The inductive ballast 90 has an input end receiving the external ac voltage, and an output end coupled to a rectifying circuit 80 and outputting an ac voltage to the rectifying circuit 80. The rectifying circuit 80 rectifies the alternating current voltage output by the inductive ballast 90 to obtain a Direct Current (DC) input voltage V_in(ii) a The LED driving circuit 70 is for receiving an input voltage V_inAnd driving the LED groups to emit light. The output end of the rectifying circuit 80 is connected across a driving capacitor C_inDriving capacitor C_inFor reducing ripples in the electrical signal input by the LED driver circuit. One end of the sampling module 10 is coupled to the input end of the LED driving circuit to receive the input voltage V_inThe other end is coupled to the signal processing module 20 and provides the input voltage V to the signal processing module 20_inA corresponding first output signal.

The switch module 30 includes a transistor Q₃(which may be referred to as a switching transistor), the output terminal of the signal processing module 20 is coupled to the switching transistor Q₃The control terminal of (1). Switching transistor Q₃One end of which is coupled with a first diode D₁The first diode D₁Is coupled to the cathode of the LED group, and a switching transistor Q₃And the other end of the second switch is connected to ground potential. Switching transistor Q₃The LED group, which is a component of the shunt circuit in the spike voltage elimination circuit, is turned on or off in response to the output signal of the signal processing module 20. The timing module 50 is coupled to the signal processing module 20, and the timing module 50 is configured to control an output signal of the signal processing module 20, so as to control the switching transistor Q₃The on-time of (c).

In some embodiments, as shown in FIG. 7, the driver circuit 70 includes a buck converter (buck) circuit. Wherein the driving inductance L in the driving circuit 70₃LED group and first diode D₁And a switching transistor Q3 in series. First diode D₁Preventing reverse current flow and may be omitted in some embodiments. In some casesIn one embodiment, the driving circuit 70 is included in an integrated buck converter module. Input voltage V input to the drive circuit 70_inAt the start of the rise, the driving switching transistor Q in the driving circuit 70₂In response to a switching signal V_buckBut is turned on, but the driving circuit 70 does not yet start outputting a voltage sufficient to drive the LED group to emit light.

At this time, the sampling module 10 samples the input voltage V_inSampling is carried out, and the signal processing module 20 judges the input voltage V according to the output of the sampling module 10_inWhether it reaches the preset voltage value and the input voltage V_inThe switching transistor Q is switched on when a predetermined voltage value is reached₃. From an input voltage V_inStarting from the start of the lift, a start-up time t elapses_onThen, the driving circuit 70 starts to output a voltage sufficient to drive the LED group to emit light, and then the signal processing module 20 controls the switching transistor Q under the action of the timing module 50₃Off and the LED group is normally driven by the driving circuit 70 to emit light.

By switching transistor Q₃For NMOS transistor as an example, at input voltage V_inWhen the voltage value has not reached the predetermined voltage value, the output of the signal processing module 20 is a low level signal, and the transistor Q is switched on₃Keeping turning off; at an input voltage V_inAfter reaching the preset voltage value, the output of the signal processing module 20 becomes a high level signal, switching the transistor Q₃On, the LED group is driven to emit light, and then the transistor Q is switched₃Off and the LED group is normally driven by the driving circuit 70 to emit light.

In some embodiments, as shown in FIG. 8, the driver circuit 70 includes a boost converter (boost) circuit. Wherein the driving inductance L in the driving circuit 70₃LED group and first diode D₁And a switching transistor Q3. In some embodiments, the driving circuit 70 is included in an integrated boost converter module. Input voltage V input to the drive circuit 70_inAt the start of the rise, the driving switching transistor Q in the driving circuit 70₂In response to a switching signal V_boostAnd is turned on, at this time, the driving circuit 70 has not yet started outputting enough power to drive the LED set to emit lightThe voltage of (c). Sampling module 10 for input voltage V_inSampling is carried out, and the signal processing module 20 judges the input voltage V according to the output of the sampling module 10_inWhether it reaches the preset voltage value and the input voltage V_inThe switching transistor Q is switched on when a predetermined voltage value is reached₃. When the input voltage V_inStarting from the start of the lift, a start-up time t elapses_onThen, the driving circuit 70 starts to output a voltage sufficient to drive the LED group to emit light, and then the signal processing module 20 controls the switching transistor Q under the action of the timing module 50₃Off and the LED group is driven by the drive circuit 70 to emit light.

By switching transistor Q₃For NMOS transistor as an example, at input voltage V_inWhen the voltage value has not reached the predetermined voltage value, the output of the signal processing module 20 is a low level signal, and the transistor Q is switched on₃Remains off at the input voltage V_inAfter reaching the preset voltage value, the output of the signal processing module 20 becomes a high level signal, switching the transistor Q₃On, the LED group is driven to emit light, and then the transistor Q is switched₃Off and the LED group is normally driven by the driving circuit 70 to emit light. Wherein, in some embodiments, the first diode D₁Are omitted.

In some embodiments, as shown in fig. 9, the driving circuit 70 includes a buck converter (buck) circuit, an output terminal of the rectifying circuit 80 is coupled to an input terminal of an auxiliary circuit 71 to output a dc voltage signal to the auxiliary circuit 71, and an output terminal of the auxiliary circuit 71 supplies power to the driving circuit 70, wherein the auxiliary circuit 71 includes a boost converter (boost) circuit. In some embodiments, the auxiliary circuit 71 is included in an integrated boost converter module. Drive inductor L in drive circuit 70₃LED group and first diode D₁And a switching transistor Q3. In some embodiments, the driving circuit 70 is included in an integrated buck converter module. Input voltage V input to the drive circuit 70_inAt the start of the rise, the driving switching transistor Q in the driving circuit 70₂In response to a switching signal V_buckBut is turned on, but the driving circuit 70 does not output enough power to drive the LED setThe voltage at which light is emitted.

At this time, the sampling module 10 samples the input voltage V_inSampling is carried out, and the signal processing module 20 judges the input voltage V according to the output of the sampling module 10_inWhether it reaches the preset voltage value and the input voltage V_inThe switching transistor Q is switched on when a predetermined voltage value is reached₃. From an input voltage V_inStarting from the start of the lift, a start-up time t elapses_onThen, the driving circuit 70 starts to output a voltage sufficient to drive the LED group to emit light, and then the signal processing module 20 controls the switching transistor Q under the action of the timing module 50₃Off and the LED group is normally driven by the driving circuit 70 to emit light. By switching transistor Q₃For NMOS transistor as an example, at input voltage V_inWhen the voltage value has not reached the predetermined voltage value, the output of the signal processing module 20 is a low level signal, and the transistor Q is switched on₃Remain off. At an input voltage V_inAfter reaching the preset voltage value, the output of the signal processing module 20 becomes a high level signal, switching the transistor Q₃And when the LED group is conducted, the LED group is driven to emit light. Then, the transistor Q is switched₃Off and the LED group is normally driven by the driving circuit 70 to emit light. In some embodiments, the first diode D₁Are omitted.

In some embodiments, as shown in fig. 10, the driving circuit 70 includes a flyback (flyback) circuit, the output terminal of the rectifying circuit 80 is coupled to the input terminal of an auxiliary circuit 71, and the output terminal of the auxiliary circuit 71 supplies power to the driving circuit 70, wherein the auxiliary circuit 71 includes a boost converter (boost) circuit. In some embodiments, the auxiliary circuit 71 is included in an integrated boost converter module. In some embodiments, the driving circuit 70 is included in an integrated flyback converter module. The shunt circuit 40 includes a shunt resistor R_LShunt resistance R_LOne terminal of the transistor is coupled to the input terminal of the driving circuit 70, and the other terminal is coupled to the switching transistor Q₃. Input voltage V input to the drive circuit 70_inAt the start of the rise, the driving switching transistor Q in the driving circuit 70₂In response to a switching signal V_flybkBut is turned on, but the driving circuit 70 does not start outputting enough at this timeTo drive the LED groups to emit light. At this time, the sampling module 10 samples the input voltage V_inSampling is carried out, and the signal processing module 20 judges the input voltage V according to the output of the sampling module 10_inWhether it reaches the preset voltage value and the input voltage V_inThe switching transistor Q is switched on when a predetermined voltage value is reached₃。

At the switching transistor Q₃When conducting, a current flows through the shunt resistor R_LAnd a switching transistor Q₃Shunt resistance R_LReceiving an input voltage V as a load_inInput voltage V_inNo longer rises over time. From an input voltage V_inStarting from the start of the lift, a start-up time t elapses_onThen, the driving circuit 70 starts to output a voltage sufficient to drive the LED group to emit light, and then the signal processing module 20 controls the switching transistor Q under the action of the timing module 50₃Off and the LED group is normally driven by the driving circuit 70 to emit light. By switching transistor Q₃For NMOS transistor as an example, at input voltage V_inWhen the voltage value has not reached the predetermined voltage value, the output of the signal processing module 20 is a low level signal, and the transistor Q is switched on₃Remain off. At an input voltage V_inAfter reaching the preset voltage value, the output of the signal processing module 20 becomes a high level signal, switching the transistor Q₃Conducting, and driving the LED group to emit light; then, the transistor Q is switched₃Turn-off and shunt resistor R_LNo current flows through it.

In some embodiments, the signal processing module 20 includes a hysteresis voltage comparator. Fig. 11 shows a circuit diagram of a spike voltage elimination circuit, and the shunt circuit includes an LED group. To clearly describe the operation principle of the spike voltage elimination circuit, fig. 11 also shows a part of the driving circuit 70, including the driving capacitor C_inAnd a driving inductor L₃And a second diode D₂. The sampling module 10 comprises a first resistor R connected in series in sequence₁A second resistor R₂And a third resistor R₃Wherein the first resistor R₁For receiving an input voltage V_inThe second terminal is coupled to the second resistorR₂. Third resistor R₃Is coupled to the second resistor R₂And Operational Amplifier (Operational Amplifier) U₁And the second end of the non-inverting input end of the transformer is connected with the ground potential. Operational amplifier U₁The inverting input terminal of the Voltage Regulator is connected with an integrated Voltage Regulator IC U₂Wherein a voltage stabilizing circuit U is integrated₂For inverting operational amplifier U₁Provides a stable reference voltage. Integrated voltage stabilizing circuit U₂Through a fourth resistor R₄Supplied by a supply voltage VCC. Operational amplifier U₁Is passed through a fifth resistor R₅Coupling switch transistor Q₃A gate electrode of (1). The timing module 50 includes a transistor Q₆And a capacitor C₁. Wherein the transistor Q₆Is passed through a sixth resistor R₆Coupled operational amplifier U₁The other end of the same-phase input end of the grid is connected with the ground potential, and the grid is electrically connected with a capacitor C₁First terminal of (1), capacitor C₁Is connected to ground potential. Capacitor C₁The first end of the resistor also passes through a seventh resistor R₇Coupled operational amplifier U₁To the output terminal of (a). Eighth resistor R₈One end is coupled with a switch transistor Q₃Has its gate connected to ground potential and the other end connected to ground potential for switching transistor Q₃Is pulled to ground potential when the gate state of the transistor is uncertain, so as to avoid switching the transistor Q₃And (5) damaging. Ninth resistor R₉One end is coupled with an operational amplifier U₁The non-inverting input terminal and the other terminal of the same are coupled with an operational amplifier U₁To the output terminal of (a).

When the first resistor R₁A first terminal of the first transistor receives an input voltage V_inInput voltage V_inAt a first resistance R₁A second resistor R₂And a third resistor R₃After voltage division, the third resistor R₃Voltage on is input to an operational amplifier U₁The non-inverting input terminal of (1). Wherein, the operational amplifier U₁The magnitude of the voltage at the non-inverting input of (a) can be calculated as follows:

V₊＝V_in*R₃/(R₁+R₂+R₃)

and an operational amplifier U₁Voltage V at the inverting input terminal of_-By the integrated voltage-stabilizing circuit U₂Provided is a method. At an input voltage V_inAt lower times, the operational amplifier U₁Voltage V at the non-inverting input terminal of₊Lower than the voltage V on the inverting input_-Operational amplifier U₁The output terminal of the switch transistor outputs a low level signal, the switch transistor Q₃And (6) cutting off. According to the above formula, with the input voltage V_inGradually rising, operational amplifier U₁Voltage V at the non-inverting input terminal of₊And also gradually increases. When the operational amplifier U₁Voltage V at the non-inverting input terminal of₊Higher than the voltage V at the inverting input_-Operational amplifier U₁Becomes a high level signal through the fifth resistor R₅Controlling a switching transistor Q₃Is turned on, and the anode of the LED group as the shunt circuit 40 is driven by the input voltage V_inDriven inductor L₃Power is supplied, and the other end passes through a first diode D₁And a switching transistor Q₃Ground potential is connected. Thus, the LED group is already energized and emits light before the LED driving circuit 70 completes the startup.

At this time, since the operational amplifier U₁Is a high level signal which is passed through a seventh resistor R₇To the capacitor C₁Charging, capacitance C₁The voltage at the two ends is gradually increased from the low level. In the capacitor C₁The voltage across is lower than that of transistor Q₆At the threshold voltage of (2), the transistor Q₆Cutting off; with the capacitance C₁The voltage across rises and reaches the transistor Q₆Threshold voltage of, transistor Q₆Conducting, operational amplifier U₁Voltage V at the non-inverting input terminal of₊Is pulled low in an operational amplifier U₁Voltage V at the non-inverting input terminal of₊Lower than the voltage V at the inverting input_-Time-of-flight operational amplifier U₁Becomes a low level signal through the fifth resistor R₅Controlling a switching transistor Q₃When the LED group is cut off, the LED group does not pass through the switching transistor Q any more₃Ground potential is connected.

Capacitor C₁Charging ofTime T_aCan be calculated as follows:

T_a＝-R₇*C₁*ln{1–[V_{th_on}/(VCC–1)]}

in the above formula V_{th_on}Is a transistor Q₆The threshold voltage of (2). As can be seen from the above formula, by providing the seventh resistor R₇Resistance value and capacitance C₁Can set the switching transistor Q₃Thereby protecting the LED and the switching transistor Q₃。

Due to the ninth resistor R₉One end is coupled with the operational amplifier U₁The non-inverting input terminal and the other terminal of the non-inverting input terminal are coupled to an operational amplifier U₁Thus the ninth resistor R₉Is an operational amplifier U₁Providing a positive feedback, operational amplifier U₁And a ninth resistor R₉Forming a voltage hysteresis comparator which makes the operational amplifier U₁Is different from the threshold of the output low level (i.e. the threshold of the input signal corresponding to the inversion from the output low level to the high level and the threshold of the input signal corresponding to the inversion from the output high level to the low level), which makes the operational amplifier U different₁The switching frequency (slew) of (a) is reduced, and the operational amplifier U can be increased by a suitable amount₁Time of single output high level.

Among them, in some embodiments, the integrated voltage regulator circuit U₂Selecting TL-431 or TL-431A controllable precise voltage stabilizing source and operational amplifier U₁Model number LM 258. In some embodiments, the first diode D₁Are omitted.

In some embodiments, the switch module 30 includes a relay (relay) SW that replaces the switch transistor Q₃. As shown in fig. 12, the two ends of the relay SW are respectively coupled to the LED group and the ground potential. When the operational amplifier U₁When the output end of the LED lamp outputs a high level signal, the relay SW is closed, and the LED group is connected with the ground potential through the relay SW; when the operational amplifier U₁When the output end of the LED module outputs a low level signal, the relay SW is disconnected, and the LED group is not connected with the ground potential through the relay SW any more. Spike power shown in fig. 12Except for the above differences, the structure and operation principle of the voltage cancellation circuit are identical to those of the corresponding part of the circuit shown in fig. 11, and therefore, the descriptions thereof are omitted and are included herein by reference. In some embodiments, the relay SW is a long-life relay, so as to prolong the service life of the spike voltage eliminating circuit and the LED lamp tube.

In some embodiments, the signal processing module 20 includes a tenth resistor R₁₀. As shown in fig. 13, a tenth resistor R₁₀Is used for receiving the power supply voltage VCC, a tenth resistor R₁₀The second terminal of the first transistor is coupled to an operational amplifier U₁To the output terminal of (a). Operational amplifier U at this time₁And a tenth resistor R₁₀Forming a voltage comparator (but not a voltage hysteresis comparator). Operational amplifier U₁Voltage V at its non-inverting input₊Higher than the inverting input terminal V_-Time-out high level signal, voltage V at non-inverting input terminal thereof₊Lower than the inverting input terminal V_-And outputs a low level signal. Except for the above differences, the other parts of the spike voltage elimination circuit shown in fig. 13 are identical to the corresponding parts of the circuit shown in fig. 11 in structure and operation principle, and therefore are not described again and are included herein by reference.

In some embodiments, operational amplifier U₁The reference voltage at the inverting input terminal of the voltage divider is obtained by dividing the voltage by resistors. As shown in FIG. 14, the integrated voltage regulator circuit U in the signal processing module 20₂Is cancelled. The signal processing module 20 further comprises an eleventh resistor R₁₁. Eleventh resistor R₁₁Is coupled with an operational amplifier U₁And the other end of the inverting input end of the second switch is connected with the ground potential. Operational amplifier U₁Is the eleventh resistor R₁₁The voltage across the terminals. Except for the above differences, the other parts of the spike voltage elimination circuit shown in fig. 14 are identical to the corresponding parts of the circuit shown in fig. 11 in structure and operation principle, and therefore are not described again and are included herein by reference. Wherein, the operational amplifier U₁The magnitude of the voltage at the inverting input of (a) can be calculated as follows:

V_-＝VCC*R₁₁/(R₄+R₁₁)

the embodiment shown in fig. 11 to 14 employs LEDs₁To the LED_nThe constituent LED groups are part of a shunt circuit 20. In other embodiments, the LED groups are not included in the shunting circuit 20. In some embodiments, as shown in FIG. 15, shunt resistor R_LIs coupled to an input terminal of the LED driving circuit 70 and is used for receiving an input voltage V_inThe second terminal is coupled to the switching transistor Q₃. At the switching transistor Q₃When the current is conducted in response to the output signal of the signal processing module 20, the shunt resistor R_LConnected to ground potential via a switching transistor Q3, a shunt resistor R_LWherein a current flows. In other embodiments, referring to FIG. 16, shunt capacitance C_LIs coupled to an input terminal of the LED driving circuit 70 and is used for receiving an input voltage V_inThe second terminal is coupled to the switching transistor Q₃. At the switching transistor Q₃When the shunt capacitor C is turned on in response to the output signal of the signal processing module 20_LA shunt capacitor C connected to ground potential via a switching transistor Q3_LCurrent flows through; in shunt capacitance C_LThe voltage between the two ends is less than the input voltage V_inWhen the current is a shunt capacitor C_LAnd (6) charging.

It will be appreciated by those skilled in the art that the spike voltage cancellation circuit is not limited to application to the circuit shown in fig. 15 or 16. In fact, the spike voltage elimination circuit can be applied to any existing circuit (for example, a circuit for driving an LED), such as the circuits shown in fig. 7, fig. 8 or fig. 10, which are not described herein again and are included herein by reference.

To the LED fluorescent tube, especially under the condition that the LED fluorescent tube adopted the inductance type ballast power supply, the utility model provides a peak voltage elimination circuit can reduce or even eliminate the peak voltage that components and parts among the LED drive circuit among the LED fluorescent tube bore. Therefore, the voltage stress condition borne by components in the LED driving circuit is also improved. FIG. 17 shows an embodiment of the present inventionExample input voltage V of the LED drive circuit_inAnd LED drive current I_LEDWherein the LEDs in the LED tube are also part of the shunt circuit 40. After the LED lamp is energized, the inductive ballast 90 supplies power to the lamp through the rectifying circuit 80, and the input voltage V of the LED driving circuit 70_inGradually rising. And the switch module 30 is turned on and energizes the LEDs in the tube for a period of time. During this time, the LED driving current I flowing through the LED in the lamp tube_LEDThe LED is driven to emit light and form a current pulse, while the input voltage V of the LED drive circuit 70_inClamped at about 462V without rising above 500V and even to a peak voltage of 550V.

After the start-up time t from the start of the power supply of the inductive ballast 90 to the circuit_onAfter (about 60ms), the LED driving circuit 70 starts to operate normally, and the LED drives the current I_LEDThe LED is driven to stably emit light. Fig. 18 shows an input voltage V of an LED driving circuit according to another embodiment of the present invention_inLED drive current I_LEDAnd switching transistor Q of the peak voltage cancelling circuit₃Drive voltage V_Q3Schematic diagram of the waveform of (1). Wherein the driving voltage V_Q3The transistor Q is switched on and off by forming a plurality of pulse signals before the LED drive circuit 70 starts to operate normally₃Accordingly, the peak voltage eliminating circuit in the lamp tube can eliminate a plurality of peak voltages which may occur.

The foregoing is a more detailed description of the present invention, taken in conjunction with the specific preferred embodiments thereof, and it is not intended that the invention be limited to the specific embodiments shown and described. The various embodiments of the present invention can be combined with each other without causing contradiction, and thus various variations of the embodiments can be actually made. To the utility model belongs to the technical field of ordinary technical personnel, do not deviate from the utility model discloses under the prerequisite of the design, can also make a plurality of simple deductions or replacement, all should regard as belonging to the utility model discloses a protection scope.

Claims

1. A spike voltage cancellation circuit, comprising:

the sampling module is used for sampling a voltage signal and generating a first output signal based on the voltage signal;

the signal processing module is coupled to the sampling module and used for comparing the first output signal with a reference voltage signal and outputting a comparison result signal;

the switch module is coupled to the signal processing module and used for enabling the current of the voltage signal to flow through a shunt circuit according to the conduction of the comparison result signal; and

and the timing module is coupled with the input end and the output end of the signal processing module and is used for controlling the conduction time of the switch module.

2. The spike voltage cancellation circuit of claim 1, wherein the shunt circuit comprises a shunt resistor, a first end of the shunt resistor is configured to receive the voltage signal, and a second end of the shunt resistor is connected to a ground potential via the switch module.

3. The spike voltage cancellation circuit of claim 1, wherein the shunt circuit comprises a shunt capacitor having a first terminal for receiving the voltage signal and a second terminal connected to a ground potential via the switch module.

4. The circuit of claim 1, wherein the shunting circuit comprises a set of LEDs and a transistor; the anode of the LED group is used for receiving the voltage signal, and the cathode of the LED group is connected with one end of the transistor; the other end of the transistor is connected with the ground potential, and the control end of the transistor is turned on or off in response to a starting signal, so that the LED group emits light or stops emitting light; the cathode of the LED group is further coupled with the switch module.

5. The circuit of claim 1, wherein the shunting circuit comprises a group of LEDs, a LED driver circuit; the LED driving circuit is used for receiving the voltage signal and driving the LED group to emit light; one end of the switch module is coupled to the cathode of the LED group, the other end of the switch module is connected to a ground potential, and the control end of the switch module is responsive to the comparison result signal to turn on the switch module to enable the current of the voltage signal to flow through the shunt circuit.

6. The spike voltage cancellation circuit of claim 5, wherein the switch module comprises a switch transistor, one end of the switch transistor is coupled to the cathode of the LED set, the other end of the switch transistor is connected to ground potential, and a control end of the switch transistor is coupled to the output end of the signal processing module.

7. The spike voltage cancellation circuit of claim 6 wherein the switching transistor is coupled to the cathode of the LED group via a first diode.

8. The spike voltage cancellation circuit of claim 5 wherein the LED driving circuit comprises a buck converter circuit, and a driving inductor of the buck converter circuit is connected in series with the LED group and the switch module.

9. The spike voltage cancellation circuit of claim 8 further comprising an auxiliary circuit, said auxiliary circuit comprising a boost converter circuit; the input end of the auxiliary circuit is used for receiving a voltage signal from a rectifying circuit, and the output end of the auxiliary circuit is coupled to the input end of the buck conversion circuit so as to provide the voltage signal for the buck conversion circuit.

10. The spike voltage cancellation circuit of claim 5 wherein the LED driver circuit comprises a boost converter circuit, and a driving inductor of the boost converter circuit is connected in series with the LED group and the switch module.

11. The circuit of claim 1 or 5, further comprising an auxiliary circuit and an LED driver circuit, wherein the auxiliary circuit comprises a boost converter circuit; the LED driving circuit comprises a flyback circuit; the input end of the auxiliary circuit is used for receiving a voltage signal from a rectifying circuit, and the output end of the auxiliary circuit is coupled to the input end of the flyback circuit so as to provide the voltage signal for the flyback circuit.

12. The circuit of claim 1, further comprising an LED driving circuit, wherein one end of the shunt circuit is coupled to the output end of the LED driving circuit, and the other end of the shunt circuit is coupled to the switch module.

13. The spike voltage cancellation circuit of claim 12, wherein the shunt circuit comprises a shunt resistor, one end of the shunt resistor is coupled to the input terminal of the LED driving circuit, and the other end of the shunt resistor is coupled to the switch module.

14. The spike voltage cancellation circuit of claim 1 wherein the signal processing module comprises a hysteretic voltage comparator.

15. The spike voltage cancellation circuit of claim 1, wherein the timing module comprises a transistor, one end of the transistor is coupled to the input terminal of the signal processing module, the other end of the transistor is connected to ground potential, and a control terminal of the transistor is coupled to one end of a capacitor; the other end of the capacitor is connected with the ground potential.

16. The spike voltage cancellation circuit of claim 15, wherein the transistor is turned on when the voltage across the capacitor rises to the threshold voltage of the transistor, such that the input of the signal processing module is grounded via the transistor.

17. The spike voltage cancellation circuit of claim 1 wherein the switch module comprises a relay.

18. The spike voltage cancellation circuit of claim 1 wherein the sampling module is configured to receive the voltage signal and send the first output signal to the signal processing module in response to the voltage signal.

19. The spike voltage cancellation circuit of claim 1, wherein the sampling module comprises at least two series-connected resistors.