CN219919227U

CN219919227U - Active rectifying circuit, LED driver and LED lighting device

Info

Publication number: CN219919227U
Application number: CN202320904170.7U
Authority: CN
Inventors: 石亮; 王钰; 李康
Original assignee: Signify Holding BV
Current assignee: Signify Holding BV
Priority date: 2023-04-19
Filing date: 2023-04-19
Publication date: 2023-10-27
Anticipated expiration: 2033-04-19

Abstract

The application is suitable for the circuit field, and provides an active rectifying circuit, an LED driver and an LED lighting device, wherein the active rectifying circuit is provided with an energy storage element between an alternating current live wire input and an alternating current zero wire input, so that the energy storage element is charged by normal working voltage (voltage for switching on a rectifying transistor of the active rectifying circuit) received by the active rectifying circuit and is discharged by opposite polarity surges, the discharging of the energy storage element is amplified by an amplifying circuit and then provided for a turn-off circuit, the turn-off circuit uses the amplified current to turn off a transistor which is currently conducted, thereby realizing timely response when a transient signal such as a surge is reached, and closing the relevant transistor which is currently conducted before a line/inherent voltage passes through the zero point, so that the short circuit of the alternating current live wire input and the alternating current zero wire input is avoided by the transistor before the surge line/inherent voltage passes through the zero point, and the safe operation of the circuit is ensured.

Description

Active rectifying circuit, LED driver and LED lighting device

Technical Field

The application belongs to the technical field of illumination, and particularly relates to a light-emitting module and illumination equipment.

Background

Currently, there are two main approaches that can help reduce the power loss of bridge rectifiers. The first is bridgeless PFC (Power Factor Correction ), which integrates PFC circuits with bridge rectifiers, and is very complex to control. The second is an active bridge that replaces the bridge diode with four field effect transistors (Field Effect Transistor, FET) to minimize the power loss of the bridge rectifier; but this provides independent control for each FET, detects the power supply zero crossing through the resistor divider to drive the low-side FET, and uses the high-side driver to synchronize the high-side FET with the low-side FET, providing a high response to power supply fluctuations. However, since the high-low side driver is not grounded as a reference, the high-side driver still has transient signal response hysteresis such as surge, namely, when the surge arrives, the FET can not be turned off in time to block the surge, so that the problem of circuit safety is affected.

Disclosure of Invention

The embodiment of the utility model provides an active rectifying circuit, an LED driver and LED lighting equipment, which can solve the problem that the active rectifying circuit in the prior art has transient signal response hysteresis such as surge and the like, thereby influencing the circuit safety.

The application is characterized in that: an active rectifying circuit is provided, an energy storage element is arranged between an alternating current live wire input and an alternating current zero line input, so that the energy storage element is charged by normal voltage currently received by the active rectifying circuit (namely, the voltage for switching on a rectifying transistor of the active rectifying circuit) and is discharged by surge with opposite polarity, an amplifying circuit is arranged to amplify discharge current of the energy storage element and then generate amplified current to be provided for a switching-off circuit, the switching-off circuit uses the amplified current to switch off the currently-conducted rectifying transistor, and the switching-off circuit can be accelerated to switch off the transistor due to the fact that the amplifying current is used to switch off, so that transient signals such as surge can be responded timely when coming, the relevant currently-conducted transistor is switched off before the line/inherent voltage passes through the zero point, the fact that the current transistor is used to short the alternating current live wire input and the alternating current zero line input before the surge line/inherent voltage passes through the zero point is avoided, and safe operation of the circuit is ensured.

In a first aspect, an embodiment of the present application provides an active rectifier circuit, including an ac live input, an ac neutral input, a rectifier circuit including transistors, and a dc output, where the rectifier circuit includes a first transistor, and the first transistor is turned on when a voltage of a first polarity is between the ac live input and the ac neutral input, and further includes:

A first energy storage element connected between said ac hot input and said ac neutral input and charged by a voltage of said first polarity and discharged by a surge between said ac hot input and said ac neutral input opposite said first polarity;

a first amplifying circuit connected between said first energy storage element and said ac hot input and said ac neutral input for generating a first amplified current that is amplified based on said discharging of said first energy storage element;

and the first turn-off circuit is connected between the first amplifying circuit and the first transistor and is used for turning off the first transistor by using the first amplifying current.

In an embodiment of the present application, the first energy storage element is charged on the premise of receiving the voltage of the first polarity and turning on the first transistor to rectify the voltage of the first polarity. If a surge of opposite polarity to the first polarity occurs next to the input, the first energy storage element can be discharged by the surge of opposite polarity to the first polarity, so that the first energy storage element can provide a larger discharge current as it has been precharged. And the first amplifying circuit can amplify the discharge current to obtain an amplified current, and the first turn-off circuit can drive/turn off the first transistor based on the amplified current so as to be turned off before the voltage of the first polarity is reduced to zero, so that the surge is prevented from shorting the alternating current live wire input and the alternating current zero wire input through the first transistor, and the safety of the circuit is ensured.

In one embodiment, the first turn-off circuit comprises a pump circuit connected between the first amplifying circuit and the control electrode of the first transistor for pumping charge from the control electrode of the first transistor with the first amplifying current to turn off the first transistor.

In this embodiment, the first turn-off circuit is turned on according to the first amplifying current, so that the charge at the control electrode of the first transistor is pumped away with the first discharging current, so that the first transistor is turned off, and since the pumped current is amplified, the pumping speed is fast, the residual charge at the control electrode of the first transistor can be pumped away faster to turn off, so that the short circuit path between the ac live wire input and the ac neutral wire input is turned off, and thus the surge impact is avoided. It will be appreciated that the current-drawing circuit may be a wire, or a wire provided with a transistor which may be driven on by the first turn-off circuit.

In one embodiment, the rectifying circuit further comprises a second transistor paired with the first transistor, wherein the first transistor is connected between the ac neutral input and the positive pole of the dc output, and the second transistor is connected between the ac hot input and the positive pole of the dc output; the first transistor is turned on at the voltage of the first polarity to connect the ac neutral input to the positive pole of the dc output, and the second transistor is turned off at the voltage of the first polarity, the first polarity being that the ac neutral input is positive.

In this embodiment, the first transistor and the second transistor are paired as high-side switches of the rectifying circuit, and in the case where the ac live input and the ac neutral input have a line/natural voltage input, the first transistor and the second transistor are alternately turned on to rectify and output the input ac, where the first polarity is positive polarity of the ac neutral input, which means that the current direction is negative polarity voltage from the ac neutral input to the ac live input, that is, the ac input is in a negative half cycle.

In one embodiment, the second transistor has a forward biased body diode from the ac hot input to the positive side of the dc output, the body diode of the second transistor being capable of being turned on by a surge of opposite polarity to the first polarity between the ac hot input and the ac neutral input;

but the first turn-off circuit turns off the first transistor to avoid the surge from passing through the first transistor to avoid shorting the ac hot input and the ac neutral input.

In this embodiment, since the rectifying circuit is constituted by transistors having body diodes, among the paired first and second transistors. Wherein, when the alternating current input is in the negative half period, the first transistor is turned on, the second transistor is turned off, and if the second transistor is in a surge with the polarity opposite to the first polarity (which can be understood as positive polarity), the body diode of the second transistor is turned on, and if the first transistor is not turned off in time, the surge will short-circuit the alternating current live wire input and the alternating current zero wire input, thereby damaging the subsequent-stage circuit. Therefore, the first switching-off circuit switches off the first transistor when a surge occurs, so that the circuit can be ensured to operate without being damaged.

In one embodiment, the first energy storage element comprises a first capacitance connected between the ac hot input and the ac neutral input.

In this embodiment, a first energy storage element is provided, and it is understood that the voltage of the first capacitor will change synchronously with the voltage between the ac neutral input and the ac hot input, for example, when the ac input is in a negative half-cycle and a positive polarity surge occurs, the first capacitor will discharge to the first amplifying circuit following the voltage decrease between the ac neutral input and the ac hot input, so as to provide a first amplifying current to cause the first switching circuit to turn off the first transistor, thereby preventing the surge from shorting the ac neutral input and the ac hot input. The first capacitor may be a separate dedicated capacitor element, may be a parasitic capacitor of another device, such as a parasitic capacitor of a semiconductor device, or may be both connected in parallel.

In one embodiment, a first pole of the first capacitor is connected to the ac hot input, a second pole of the first capacitor is connected to the ac neutral input, and the active rectifying circuit further comprises a unidirectional element for unidirectional allowing a voltage of the first polarity to charge the first capacitor;

The first amplifying circuit comprises a first darlington circuit, a base electrode of the first darlington circuit is connected to a second pole of the first capacitor, an emitter electrode of the first darlington circuit is connected to the alternating current zero line input and used for unidirectionally allowing the surge opposite to the first polarity to discharge the first capacitor, and a collector electrode of the first darlington circuit is connected to a control pole of the first transistor through the first turn-off circuit.

In this embodiment, different charging and discharging paths are provided for the first capacitor, and the unidirectional element is used to allow the ac input to charge the first capacitor during the negative half-cycle, i.e. to limit the current direction in which the first capacitor is charged, and to enable the voltage of the first capacitor to be charged to a voltage between the ac neutral input and the ac live input when the first transistor is turned on; when a positive surge arrives, the voltage between the alternating current zero line input and the alternating current live line input is rapidly reduced, the first capacitor is rapidly discharged to the base electrode of the first darling circuit through the first darling circuit to enable the base electrode of the first darling circuit to be conducted, and the collector electrode of the first darling circuit is used for pumping charges from the control electrode of the first transistor, so that the first transistor is turned off. It can be understood that the closing speed of the first transistor is proportional to the voltage drop speed between the ac neutral input and the ac live input, that is, the larger the surge is, the faster the closing speed of the first transistor is, so that the active rectifying circuit has high transient signal response speed such as the surge.

In one embodiment, the method further comprises:

a second energy storage element connected between said ac hot input and said ac neutral input and charged by a voltage of a second polarity, which is opposite in phase to said voltage of the first polarity, and discharged by a surge of the first polarity between said ac hot input and said ac neutral input;

a second amplifying circuit connected between said second energy storage element, said ac hot input and said ac neutral input for generating a second amplified current for amplification based on said discharging of said second energy storage element;

and a second turn-off circuit connected between the second amplifying circuit and the second transistor for turning off the second transistor using the second amplifying current.

In the embodiment of the application, the protection of the surge with the other polarity is provided. The second transistor is conducted in the positive half period of the alternating current input, so that a circuit which is turned off in response to negative polarity surge is arranged for the second transistor which is also paired with the first transistor, and therefore, when transient signals such as surge exist, the short circuit path between the alternating current live wire input and the alternating current zero line input can be turned off by two high-side switches which are lack of ground of the rectifying circuit, and the safety of the circuit is ensured.

In one embodiment, the second turn-off circuit comprises a pump circuit connected between the second amplifying circuit and the control electrode of the second transistor for pumping charge from the control electrode of the second transistor with the second amplifying current to turn off the second transistor.

In this embodiment, the second turn-off circuit is turned on according to the second amplifying current, so that the charge at the control electrode of the second transistor is pumped away with the second discharging current, so that the second transistor is turned off, and since the pumped current is amplified, the pumping speed is fast, the residual charge at the control electrode of the second transistor can be pumped away faster to turn off, so that the short circuit path between the ac live wire input and the ac zero wire input is turned off, and thus the surge impact is avoided. It will be appreciated that the current-drawing circuit may be a wire, or a wire provided with a transistor which may be driven on by the second turn-off circuit.

In one embodiment, the second transistor is turned on at a voltage of the second polarity to connect the ac hot input to the positive pole of the dc output, and the first transistor is turned off at the voltage of the second polarity, the second polarity being the positive polarity of the ac hot input.

The second polarity being that the ac line input is positive polarity means that the current direction is positive polarity voltage from the ac line input to the ac neutral input, i.e. the ac input is in the positive half cycle.

In one embodiment, the first transistor has a forward biased body diode from the ac neutral input to the positive side of the dc output, the body diode of the first transistor being capable of being turned on by a surge of the first polarity between the ac hot input and the ac neutral input;

but the second turn-off circuit turns off the second transistor to avoid the surge from passing through the second transistor to avoid shorting the ac hot input and the ac neutral input.

In this embodiment, the second transistor is turned on during the positive half cycle, the first transistor is turned off, and the body diode of the first transistor is turned on if there is a negative polarity surge, and if the second transistor is not turned off in time, the surge will short the ac live input and the ac neutral input, thereby damaging the subsequent stage circuit. Therefore, the second turn-off circuit turns off the second transistor when a surge occurs, so that the circuit can be ensured to operate without being damaged.

In one embodiment, the second energy storage element includes a second capacitance connected between the ac hot input and the ac neutral input.

In this embodiment, a second energy storage element is provided, and it is understood that the voltage of the second capacitor will change synchronously with the voltage between the ac hot input and the ac neutral input, such as when the ac input is in positive half-cycle and a positive polarity surge occurs, the second capacitor will discharge to the second amplifying circuit following the voltage decrease between the ac hot input and the ac neutral input, thereby providing a second amplified current to cause the second switch Duan Dianlu to turn off the second transistor, thereby preventing the surge from shorting the ac hot input and the ac neutral input. The second capacitor may be a separate dedicated capacitor element, may be a parasitic capacitor of another device, such as a parasitic capacitor of a semiconductor device, or may be both connected in parallel.

In one embodiment, a first end of the second capacitor is connected to the ac neutral input, a second pole of the second capacitor is connected to the ac hot input, and the active rectifying circuit further comprises a unidirectional element for unidirectional allowing the voltage of the second polarity to charge the second capacitor;

The second amplifying circuit comprises a second darling circuit, the base electrode of the second darling circuit is connected to the second pole of the second capacitor, the emitter electrode of the second darling circuit is connected to the alternating current live wire input, the second darling circuit is used for unidirectionally allowing the surge of the first pole to discharge the second capacitor, and the collector electrode of the second darling circuit is connected to the control pole of the second transistor through the second turn-off circuit.

In this embodiment, different charge and discharge paths are provided for the second capacitor, with the unidirectional element arrangement allowing the alternating current input to charge the second capacitor during the negative half cycle; when a negative surge arrives, the voltage between the alternating current live wire input and the alternating current zero wire input is rapidly reduced, the second capacitor is rapidly discharged to the base electrode of the second darling circuit through the second darling circuit to enable the base electrode of the second darling circuit to be conducted, and the collector electrode of the second darling circuit is used for pumping charges from the control electrode of the second transistor, so that the second transistor is turned off. It can be appreciated that the closing speed of the second transistor is proportional to the voltage drop speed between the ac live input and the ac neutral input, i.e. the larger the surge, the faster the closing speed of the second transistor, so that the active rectifying circuit has a high transient signal response speed such as the surge.

In one embodiment, the first energy storage element and the second energy storage element comprise capacitances, which are discrete device capacitances and/or parasitic capacitances of diodes, wherein the direction of conduction of the diodes is opposite to the charging direction of their parasitic capacitances.

In a second aspect, an embodiment of the present application provides an LED driver, including the active rectifying circuit described above.

The LED driver can improve the response of the LED driver to transient signals such as surge and the like by arranging the active rectifying circuit, so that the LED driver meets the requirements of lighting equipment.

In a third aspect, an embodiment of the present application provides an LED lighting device, including the above LED driver.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments or the description of the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a circuit schematic of an active rectifier circuit;

FIG. 2 is a schematic circuit diagram of an active rectifier circuit according to an embodiment of the present application;

fig. 3 is a circuit diagram of a specific embodiment of the implementation of the active rectifying circuit in fig. 2 according to an embodiment of the present application.

Detailed Description

Embodiments of the technical scheme of the present application will be described in detail below with reference to the accompanying drawings. The following examples are only for more clearly illustrating the technical aspects of the present application, and thus are merely examples, and are not intended to limit the scope of the present application.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the terms "comprising" and "having" and any variations thereof in the description of the application and the claims and the description of the drawings above are intended to cover a non-exclusive inclusion.

In the description of embodiments of the present application, the technical terms "first," "second," and the like are used merely to distinguish between different objects and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated, a particular order or a primary or secondary relationship. In the description of the embodiments of the present application, the meaning of "plurality" is two or more unless explicitly defined otherwise.

Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Those of skill in the art will explicitly and implicitly appreciate that the embodiments described herein may be combined with other embodiments.

In the description of the embodiments of the present application, the term "and/or" is merely an association relationship describing an association object, and indicates that three relationships may exist, for example, a and/or B may indicate: a exists alone, A and B exist together, and B exists alone. In addition, the character "/" herein generally indicates that the front and rear associated objects are an "or" relationship.

In the description of the embodiments of the present application, the term "plurality" means two or more (including two), and similarly, "plural sets" means two or more (including two), and "plural sheets" means two or more (including two).

In the description of the embodiments of the present application, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured" and the like should be construed broadly and may be, for example, fixedly connected, detachably connected, or integrally formed; or may be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the embodiments of the present application will be understood by those of ordinary skill in the art according to specific circumstances.

Referring to fig. 1, in general, an active rectifier circuit generally includes an ac live input L, an ac neutral input N, a rectifier circuit composed of rectifier transistors, and dc outputs out+, OUT-. The rectifying transistors of the rectifying circuit generally include a first transistor M4, a second transistor M1, a third transistor M2, and a fourth transistor M3, which form a rectifying bridge, where the first transistor M4, the second transistor M1, the third transistor M2, and the fourth transistor M3 may be a single transistor, such as a BJT (Bipolar Junction Transistor ) or a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor, metal-Oxide-semiconductor field effect transistor) device, or even a SiC (silicon carbide) or GaN (gallium nitride) device, or may be a mixture of two transistors. Alternatively, the active rectifying circuit may include only one or several rectifying transistors and several or one diode for rectifying.

The rectifying transistor is actively controlled, and it presents different conducting states to rectify according to the phase of the input signal. For example, when a voltage of a first polarity is between the ac neutral input L and the ac neutral input N, wherein the first polarity would indicate that the ac neutral input N is positive (and accordingly the ac neutral input L is negative), i.e. the ac input is in the negative half-cycle, the first transistor M4, the third transistor M2 are turned on by the respective transistor driving circuit to connect the ac neutral input N to the positive dc input out+ and the negative dc input OUT-to the ac neutral input L; when a voltage of a second polarity, opposite to the first polarity, is present between the ac live input L and the ac neutral input N, wherein the second polarity is to be indicated as positive polarity (and accordingly negative polarity) of the ac live input L, i.e. the ac input is in a positive half-cycle, the second transistor M1, the fourth transistor M3 are turned on by the respective transistor driving circuit to connect the ac live input L to the positive dc input out+ and the negative dc input OUT-to the ac neutral input N. On the other hand, the third transistor M2 and the fourth transistor M3 can be grounded (connected to the negative pole OUT of the dc output), and may be referred to as a low-side switch, while the first transistor M4 and the second transistor M1 float/are not grounded, and will be referred to as a high-side switch.

The above active rectifying circuit may have a problem when a surge occurs. Specifically, when a voltage of a first polarity is between the ac neutral input L and the ac hot input N, i.e., the ac input is in a negative half-cycle, the first transistor M4, the third transistor M2 are turned on by the corresponding transistor driving circuit to connect the ac neutral input N to the positive dc input out+ and the negative dc input OUT-to the ac hot input L. If a surge that the live wire is positive in polarity and the zero wire is negative in polarity occurs suddenly, the positive-polarity voltage reaches the source of the first transistor M4 from the ac live wire input L through the body diode of the second transistor M1, at this time, the first transistor M4 is not turned off in time, and the MOS transistor has a bidirectional conduction characteristic, so that the positive-polarity voltage reaches the ac zero wire input N through the first transistor M4 to cause a short circuit. The present utility model aims to solve this problem.

Referring to fig. 2, in a first aspect, an embodiment of the present utility model provides an active rectifying circuit, where the rectifying circuit includes a first transistor M4, and a voltage of a first polarity is between an ac live input L and the ac neutral input N, that is, the first transistor M4 is turned on during a negative half-cycle of the ac input. As mentioned above, basically, the other rectifying tubes in the rectifying circuit may be transistors (such as BJTs or MOSFETs) or diodes, or a combination of transistors and diodes, so the present utility model is not limited to the case where all rectifying tubes are transistors. The active rectifying circuit provided by the embodiment of the utility model further comprises a first energy storage element 11, a first amplifying circuit 12 and a first turn-off circuit 13.

The first energy storage element 11 is connected between the ac line input L and the ac neutral input N and is charged by a voltage of a first polarity and is discharged by a surge between the ac line input L and the ac neutral input N opposite to the first polarity. The first amplifying circuit 12 is connected between the first energy storage element 11 and the ac live input L and the ac neutral input N for generating a first amplifying current amplified based on the discharge of the first energy storage element 11. The first turn-off circuit 13 is connected between the first amplifying circuit 12 and the first transistor M4 for turning off the first transistor M4 using the first amplifying current.

In one example, such as when the ac input is in a negative half-cycle, the voltage of the first energy storage element 11 increases in response to an increase in voltage of a first polarity (i.e., positive correlation) and discharges to decrease in voltage in response to an increase in surge of a second polarity (i.e., negative correlation). It can be seen that, since the first energy storage element 11 can timely respond to the surge of the second polarity to discharge when the first transistor M4 is turned on, and the first amplifying circuit 12 can amplify the discharge current, the first turn-off circuit 13 can immediately turn off the first transistor M4 based on the amplified first amplifying current, preferably before the voltage of the first polarity is reduced to zero, so as to avoid the surge from shorting the ac live input L and the ac neutral input N through the first transistor M4, and ensure the safety of the circuit.

Referring to fig. 3, in one embodiment, the first turn-off circuit 13 includes a pumping circuit connected between the first amplifying circuit 12 and the control electrode of the first transistor M4 for pumping charge from the control electrode of the first transistor M4 with a first amplifying current to turn off the first transistor M4. It will be appreciated that the current-pumping circuit may be a wire or a wire provided with a switching transistor which may be driven on by the first turn-off circuit 13 to pump charge from the control electrode of the first transistor M4 to ground.

With continued reference to fig. 3, in one embodiment, the rectifying circuit further includes a second transistor M1, and the second transistor M1 is paired with the first transistor M4. The first transistor M4 is connected between the ac neutral input N and the positive pole out+ of the dc output, and the second transistor M1 is connected between the ac live input L and the positive pole out+ of the dc output. The first transistor M4 is turned on at a voltage of the first polarity to connect the ac neutral input N to the positive pole out+ of the dc output, and the second transistor M1 is turned off at a voltage of the first polarity. The first transistor M4 and the second transistor M1 are, for example, FETs, and are paired as high-side switches of a rectifying circuit, and when the ac live input L and the ac neutral input N have a line/natural voltage input, the first transistor M4 and the second transistor M1 are alternately turned on, thereby rectifying the input ac.

The second transistor M1 is, for example, a BJT or a MOSFET, and has a body diode forward biased from the ac live input L to the positive pole out+ of the dc output, and the body diode of the second transistor M1 can be turned on by a surge of opposite polarity to the first polarity between the ac live input L and the ac neutral input N; but the first turn-off circuit 13 turns off the first transistor M4 to avoid a surge passing through the body diode of the second transistor M1 and through the first transistor M4 to avoid shorting the ac hot input L and the ac neutral input N.

In this embodiment, since the rectifying circuit is formed by using transistors, the transistors have body diodes, and in the paired first transistor M4 and second transistor M1, the first transistor M4 is turned on and the second transistor M1 is turned off when the alternating current input is in the negative half period, if the body diode of the second transistor M1 is turned on when the surge opposite to the first polarity (which can be understood as positive polarity), if the first transistor M4 is not turned off in time, the surge will short the alternating current live input L and the alternating current zero line input N, thereby damaging the subsequent stage circuit. Therefore, the first turn-off circuit 13 turns off the first transistor M4 when a surge occurs, and the circuit operation can be ensured without being damaged.

In one embodiment, the first energy storage element 11 comprises a first capacitance C1 connected between the ac hot input L and the ac neutral input N. The first capacitor C1 may be an independent capacitor element, the first capacitor C1 may be a parasitic capacitor of other devices such as the diode D1, and the first capacitor C1 may include a dedicated capacitor element and a semiconductor device having a parasitic capacitor, which are separately disposed and connected in parallel. When the scheme is implemented, any one of the modes is optionally selected for the first capacitor C1. Additionally, in some examples, the first capacitance C1 has a capacity of 10pF-50pF.

In one embodiment, the active rectifier circuit further comprises a first diode D1, the first diode D1 being connected between the ac hot input L and the first amplifier circuit 12. In the example of fig. 3, the first energy storage element 11 further includes a first diode D1 having a parasitic capacitance. In other alternative embodiments, the first capacitance C1 may be understood as a parasitic capacitance of the first diode D1. The first diode D1 is used for reverse biasing the ac input when the first transistor M4 is turned on in the negative half period, so as to keep the first amplifying circuit 12 turned off and the voltage of the ac input on the first diode D1. If a surge occurs during this period, and during this period Applying a high positive voltage to the ac live input L and a high negative voltage to the ac neutral input N reduces the voltage difference V between the ac neutral input N and the ac live input L _NL And the reverse bias voltage on the first diode D1 will also follow V _NL And decreases.

In one embodiment, the first pole of the first capacitor C1 is connected to the ac hot input L, the second pole of the first capacitor C1 is connected to the ac neutral input N, and the active rectifying circuit further comprises a unidirectional element D2, the unidirectional element D2 being configured to unidirectional allow a voltage of the first polarity to charge the first capacitor C1, the charging path 101 being shown in fig. 3. In one embodiment, the first amplifying circuit 12 comprises a first darling circuit Q1, Q2, the bases of the first darling circuit Q1, Q2 being connected to the second pole of the first capacitor C1, the emitters of the first darling circuit Q1, Q2 being connected to the ac neutral input N for unidirectionally allowing a surge of opposite polarity to the first polarity to discharge the first capacitor C1 for responding with the discharge current of the first capacitor C1 as a very small base current and generating an amplified collector-emitter current. And the collectors of the first darling circuits Q1, Q2 are connected to the control electrode of the first transistor M4 through the first turn-off circuit 13.

The unidirectional element D2 may be a schottky diode, where an anode is connected to the ac zero line input N, and a cathode is connected to the second pole of the first capacitor C1 and the bases of the first darlington circuits Q1, Q2. On the one hand, the Schottky diode is used for unidirectionally allowing negative polarity voltage to charge the first capacitor C1; on the other hand, the schottky diode can clamp the reverse voltage on the base of the first darlington circuit Q1, Q2 within-0.5V to ensure that its base signal is always charged from-0.5V instead of a few volts to increase the first darlington circuit Q1, Q2 response.

Let voltage V across first capacitor C1 during normal operation _NL Right positive and left negative. When a surge of opposite polarity comes, V _NL Decrease to zero and reverse left positive to right negative. To prevent circuit damage, the first transistor M4 should be at V _NL Closing before dropping to zero. At V _NL During the zero transition, the first diode D1 remains reverse biased and the first powerThe capacitor C1 discharges and produces a current flowing from the right plate to the right, to the first amplifying circuit 12 and to the neutral line N, and from the hot line L to the left plate of the first capacitor C1, the discharge path 102 is shown in fig. 3. When the first capacitor C1 is discharged to the base by the surge, the first darlington circuit Q1, Q2 has its collector and emitter turned on, and extracts the charge of the control electrode of the first transistor M4 from the amplified collector-emitter current to the ac neutral input N, and the charge extraction path 103 is shown in fig. 3, and the charge extraction causes the first transistor M4 to rapidly leave the previous saturated transistor on region and enter the transistor off region, so that the first transistor M4 is turned off.

More specifically, since the first capacitor C1 is connected in parallel with the first diode D1, the voltage of the first capacitor C1 is equal to V _NL Identical, and V when the first capacitor C1 is discharged _NL The drop is very fast and the discharge current of the first capacitor C1 flows through the bases of the first darlington circuits Q1, Q2 to turn off the switching first transistor M4. If V is _NL The discharge current is higher as the drop is faster, and the higher discharge current is amplified further to help turn off the first transistor M4 faster. For normal operation without surge, the discharge current is negligible because the voltage of the ac input varies very slowly (sinusoidal waveform), because the capacitance of the first energy storage element 11 is small.

The discharge current cannot be too large depending on the actual situation. In one embodiment, the active rectifying circuit further includes a current limiting resistor R1 connected between the second pole of the first capacitor C1 and the base of the first darlington circuit Q1, Q2, where the resistance of the current limiting resistor R1 is generally larger, such as 500 k-20M ohms. And when no surge occurs and the circuit works normally, the current limiting resistor R1 is used for limiting the current input to the bases of the first darling circuits Q1 and Q2 so as to protect the first darling circuits Q1 and Q2. Meanwhile, when a wave surge occurs, the current limiting resistor R1 limits the discharge current, so that a small capacitor C2 and the current limiting resistor R1 can be connected in parallel to form a high-pass filter for providing high-pass filtering for the discharge current.

In one of the embodiments, the second transistor M1 is also provided with a circuit that turns off in response to a negative polarity surge. Specifically, referring to fig. 3, the active rectifying circuit further includes a second energy storage element 14, a second amplifying circuit 15, and a second turn-off circuit 16.

The second energy storage element 14 is connected between the ac hot input L and the ac neutral input N and is charged by a voltage of a second polarity, which is opposite in phase to the voltage of the first polarity, and discharged by a surge of the first polarity between the ac hot input L and the ac neutral input N; the second amplifying circuit 15 is connected between the second energy storage element 14, the ac live input L and the ac neutral input N, and is used for generating a second amplifying current amplified based on the discharge of the second energy storage element 14; the second turn-off circuit 16 is connected between the second amplifying circuit 15 and the second transistor M1 for turning off the second transistor M1 using the second amplifying current.

The second transistor M1 responds to negative polarity surge, so that when transient signals such as surge exist in two high-side switches of the rectifying circuit, a short circuit path between the alternating current live wire input L and the alternating current zero wire input N is cut off, the circuit safety is ensured, and in addition, the transistor can be cut off in a quickened way due to the fact that amplified current is used for cutting off.

In one embodiment, the second turn-off circuit 16 comprises a pumping circuit connected between the second amplifying circuit 15 and the control electrode of the second transistor for pumping charge from the control electrode of the second transistor M1 with the second amplifying current to turn off the second transistor M1. It will be appreciated that the current-drawing circuit may be a wire or a wire provided with a switching transistor which may be driven on by the second turn-off circuit 16.

In one embodiment, the second transistor M1 is turned on at a voltage of a second polarity, which is positive for the ac line input L, to connect the ac line input L to the positive pole out+ of the dc output, and the first transistor M4 is turned off at a voltage of the second polarity. The second polarity is that the ac hot input L is positive polarity: the current direction is the positive polarity voltage from the ac hot input L to the ac neutral input N, i.e. the ac input is in the positive half cycle.

In one embodiment, the first transistor M4 has a forward biased body diode from the ac neutral input N to the positive pole out+ of the dc output, the body diode of the first transistor M4 being capable of being turned on by a surge of a first polarity between the ac hot input L and the ac neutral input N; but the second shut off circuit 16 turns off the second transistor M1 to avoid a surge passing through the second transistor M1 to avoid shorting the ac hot input L and the ac neutral input N.

When the alternating current input is in a positive half cycle, the second transistor M1 is turned on, the first transistor M4 is turned off, if the second transistor M1 is not turned off in time when the body diode of the first transistor M4 is turned on in the presence of negative polarity surge, the surge short-circuits the alternating current live wire input L and the alternating current zero line input N, and therefore a later-stage circuit is damaged. Therefore, the second turn-off circuit 16 turns off the second transistor M1 when a surge occurs, and the circuit operation can be ensured without being damaged.

In one embodiment, the second energy storage element 14 includes a second capacitance C3 connected between the ac hot input L and the ac neutral input N. The second capacitor C3 may be a discrete dedicated capacitor element, and the second capacitor C3 may be a parasitic capacitor of the second diode D3, and the second capacitor C3 may include a discrete dedicated capacitor element and a semiconductor device having a parasitic capacitor, which are connected in parallel. When the scheme is implemented, any one of the modes is optionally selected for the second capacitor C3. In some examples, the second capacitance C3 has a capacity of 10pF-50pF.

In one embodiment, the active rectifying circuit further comprises a second diode D3, the second diode D3 being connected between the ac neutral input N and the second amplifying circuit 15. In the example of fig. 3, the second energy storage element 14 further includes a second diode D3 having a parasitic capacitance. In other alternative embodiments, the second capacitance C3 may be understood as a parasitic capacitance of the second diode D3. Wherein the second diode D3 is used for reverse biasing the AC input when the second transistor M1 is turned on in the positive half period to keep the second amplifying circuit 15 turned off and the voltage of the AC input at the second level And a pole tube D3. If a surge of negative polarity occurs during this period and a high negative voltage is applied to the ac live input L and a high positive voltage is applied to the ac neutral input N, the voltage difference V between the ac live input L and the ac neutral input N is reduced _LN And the reverse bias voltage on the second diode D3 will also follow V _LN And decreases.

In one embodiment, the first terminal of the second capacitor C3 is connected to the ac neutral input N, the second pole of the second capacitor C3 is connected to the ac hot input L, and the active rectifying circuit further comprises a unidirectional element D4, the unidirectional element D4 being for unidirectional allowing a voltage of the second polarity to charge the second capacitor C3, the second amplifying circuit 15 comprising a second darlington circuit Q3, Q4, the bases of the second darlington circuit Q3, Q4 being connected to the second pole of the second capacitor, the emitter being connected to the ac hot input L for unidirectional allowing a surge of the first polarity to discharge the second capacitor C3, for responding with the discharge current of the second capacitor C3 as a very small base current and generating an amplified collector-emitter current. And the collectors of the second darling circuits Q3, Q4 are connected to the control electrode of the second transistor M1 through the second turn-off circuit 16.

The unidirectional element D4 may be a schottky diode, whose anode is connected to the ac live input L, and whose cathode is connected to the second pole of the second capacitor C3 and to the bases of the second darlington circuits Q3, Q4. On the one hand, the Schottky diode is used for unidirectionally allowing negative polarity voltage to charge the second capacitor C3; on the other hand, the schottky diode can also increase the response of the second darlington circuits Q3, Q4.

Setting the voltage V across the second capacitor C3 during normal operation _LN Right positive and left negative. When a surge of opposite polarity comes, V _LN Decrease to zero and reverse left positive to right negative. To prevent circuit damage, the second transistor M4 should be at V _LN Closing before dropping to zero. At V _LN During the zero transition, the second diode D3 remains reverse biased and the second capacitor C3 discharges and produces a current flowing from the right plate to the right, to the second amplifying circuit 15 and to the hot line L, and from the neutral line N to the left plate of the second capacitor C3. Second darling circuit Q3, Q4When the surge discharges the second capacitor C3 to the base, the collector and emitter are turned on, and the charge at the control electrode of the second transistor M1 is extracted to the ac line input L with the aforementioned amplified collector-emitter current, which charge extraction causes the second transistor M1 to rapidly leave the previous transistor saturated on region and enter the transistor off region, thereby causing the second transistor M1 to be turned off.

It can be understood that the closing speed of the second transistor M1 is proportional to the voltage drop speed between the ac live input L and the ac neutral input N, that is, the larger the surge is, the faster the closing speed of the second transistor M1 is, so that the active rectifying circuit has a high transient signal response speed such as the surge.

It should be understood that the more specific embodiments and principles of the second energy storage element 14, the second amplifying circuit 15 and the second turn-off circuit 16 can refer to the above description of the embodiments and principles of the first energy storage element 11, the first amplifying circuit 12 and the first turn-off circuit (13), and are not repeated herein.

It will be appreciated that the first energy storage element 11 and the second energy storage element 14 comprise capacitors (i.e. the first capacitor C1 and the second capacitor C3), which are parasitic capacitors of the discrete device capacitors and/or diodes, wherein the conducting direction of the diodes is opposite to the charging direction of their parasitic capacitors.

The discharge current cannot be too large depending on the actual situation. In one embodiment, the active rectifying circuit further includes a current limiting resistor R2 connected between the second pole of the second capacitor C3 and the base of the second darlington circuit Q3, Q4, where the resistance of the current limiting resistor R2 is generally larger, such as 500 k-20M ohms. During normal operation without surge, the current limiting resistor R2 is used for limiting the current input to the bases of the second darling circuits Q3 and Q4 so as to protect the second darling circuits Q3 and Q4. Meanwhile, when a wave surge occurs, the current limiting resistor R2 limits the discharge current, so that a small capacitor C4 and the current limiting resistor R2 can be connected in parallel to form a high-pass filter for providing high-pass filtering for the discharge current.

In one embodiment, the active rectifying circuit further includes a dc power source VCC and a plurality of driving circuits, each of which is independently controlled for providing gate signals to each of the transistors M1 to M4 during normal operation without occurrence of a surge. The switching operation of the present active rectifier circuit when the ac live input L and the ac neutral input N receive normal ac operating voltages is described below.

The high-side switch takes a driving circuit of the first transistor M4 as an example, and includes a capacitor C6, a current-limiting resistor R4 and a diode D6, wherein an anode of the diode D6 is connected to the dc power VCC, a cathode is connected to one end of the capacitor C6, the other end of the capacitor C6 is connected to the ac zero line input N, one end of the current-limiting resistor R4 is connected to the cathode of the diode D6, and the other end of the current-limiting resistor R6 is connected to the control end of the first transistor M4. The diode D6 and the current limiting resistor R4 are connected between the dc power supply VCC and the control terminal of the first transistor M4. In normal operation, if the ac neutral input N is a negative voltage and the ac live input L is a positive voltage, the first darlington circuits Q1 and Q2 are turned on, the voltage of the gate electrode of the first transistor M4 is pulled down, and the first transistor M4 is turned off. Here, the difference from the aforementioned case of combating the surge is that it is not necessary to amplify and pump the rapid discharge current of the first capacitor C1. When the power supply works normally, if the input N of the alternating current zero line is positive voltage and the input L of the alternating current live wire is negative voltage, the first darlington circuits Q1 and Q2 are closed, and the direct current power supply VCC conducts the first transistor M4 through the diode D6 and the current limiting resistor R4 in a conducting/driving mode to rectify. However, since the first transistor M4 is not grounded, the control transistors of the first transistor M4 (i.e., the first Dalton circuits Q1, Q2) are only at V _NL The operation is started when the voltage is lower than the dc power supply Vcc, thereby turning off the first transistor M4. The operation of turning on and off the second transistor M1 and its peripheral circuits is similar.

The low-side switch is exemplified by a driving circuit of the third transistor M2, and includes a resistor R5, a resistor R7, a diode D7, and a switching transistor Q5. The resistor R5 is connected between the dc power VCC and the control terminal of the third transistor M2 to drive and turn on the third transistor M2. Resistor R7 is connected between dc power supply VCC and the base of switching transistor Q5, and the emitter of switching transistor Q5 is connected to ac neutral input N through diode D7. When the ac zero line input N is a positive voltage, the switching transistor Q5 is naturally turned off, and the dc power supply VCC pulls the control electrode of the third transistor M2 high to be turned on. When the voltage (Vn) between the ac zero line input N and ground (i.e. the negative OUT of the dc output) is less than Vcc-Vf (q5+d7) during the zero crossing period, the switching transistor Q5 starts to turn on and locks the voltage of the gate signal at the control terminal of the third transistor M2 to Vn. At the same time, the third transistor M2 is still on until Vn drops to (threshold voltage) Vth of the third transistor M2, i.e. the ac zero line input N drops to near zero. After which the third transistor M2 is naturally turned off. When the voltage of the ac live input L rises beyond zero, the switching transistor Q6 controlling the fourth transistor M3 is turned off, and the dc power VCC turns on the fourth transistor M3 through the resistor R6. The operation of turning off the fourth transistor M3 and its peripheral circuits is then similar to that of the third transistor M2 and its peripheral circuits.

The LED driver and the LED lighting equipment provided with the LED driver can improve the response of the LED driver to transient signals such as surge and the like by arranging the active rectifying circuit, so that the LED driver meets the requirements of the lighting equipment.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present application, and not for limiting the same; although the application has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the application, and are intended to be included within the scope of the appended claims and description. In particular, the technical features mentioned in the respective embodiments may be combined in any manner as long as there is no structural conflict. The present application is not limited to the specific embodiments disclosed herein, but encompasses all technical solutions falling within the scope of the claims.

Claims

1. An active rectifier circuit comprising an ac live input (L), an ac neutral input (N), a rectifier circuit comprising transistors and a dc output (out+, OUT-) the rectifier circuit comprising a first transistor (M4), the first transistor (M4) being on when a voltage of a first polarity is present between the ac live input (L) and the ac neutral input (N), characterized in that it further comprises:

a first energy storage element (11) connected between said ac hot input (L) and said ac neutral input (N), charged by a voltage of said first polarity, and discharged by a surge between said ac hot input (L) and said ac neutral input (N) opposite to said first polarity;

a first amplifying circuit (12) connected between said first energy storage element (11) and said ac hot input (L) and said ac neutral input (N) for generating a first amplified current amplified based on said discharging of said first energy storage element (11);

a first turn-off circuit (13) connected between the first amplifying circuit (12) and the first transistor (M4) for turning off the first transistor (M4) using the first amplifying current.

2. An active rectifier circuit according to claim 1, characterized in that the first shut-off circuit (13) comprises a pumping circuit connected between the first amplifying circuit (12) and the control electrode of the first transistor (M4) for pumping charge from the control electrode of the first transistor (M4) with the first amplifying current to shut off the first transistor (M4).

3. An active rectifying circuit according to claim 1, characterized in that said rectifying circuit further comprises a second transistor (M1), said second transistor (M1) being paired with said first transistor (M4), wherein said first transistor (M4) is connected between said ac neutral input (N) and the positive pole of said dc output, and said second transistor (M1) is connected between said ac hot input (L) and the positive pole of said dc output;

the first transistor (M4) is turned on at a voltage of the first polarity to connect the ac neutral input (N) to the positive pole of the dc output, and the second transistor (M1) is turned off at a voltage of the first polarity, the first polarity being that the ac neutral input (N) is positive.

4. An active rectifier circuit according to claim 3, characterized in that said second transistor (M1) has a body diode forward biased from said ac line input (L) to the positive pole of said dc output, said body diode of said second transistor (M1) being capable of being turned on by a surge of opposite polarity to said first polarity between said ac line input (L) and said ac neutral input (N);

But the first turn-off circuit (13) turns off the first transistor (M4) to avoid the surge from passing through the first transistor (M4) to avoid shorting the ac hot input (L) and the ac neutral input (N).

5. Active rectifier circuit according to any one of claims 1 to 4, characterized in that the first energy storage element (11) comprises a first capacitance (C1) connected between the ac live input (L) and the ac neutral input (N).

6. An active rectifier circuit according to claim 5, characterized in that a first pole of said first capacitor (C1) is connected to said ac live input (L), a second pole of said first capacitor (C1) is connected to said ac neutral input (N), and

the active rectifying circuit further comprises a first unidirectional element (D2), the first unidirectional element (D2) being for unidirectional allowing the voltage of the first polarity to charge the first capacitor (C1);

the first amplifying circuit (12) comprises a first darling circuit (Q1, Q2), the base of the first darling circuit (Q1, Q2) being connected to the second pole of the first capacitor (C1), the emitter being connected to the ac neutral input (N) for unidirectionally allowing the surge opposite to the first polarity to discharge the first capacitor (C1), and the collector being connected to the control pole of the first transistor (M4) through the first shut-off circuit (13).

7. The active rectifier circuit of claim 3, further comprising:

a second energy storage element (14) connected between said ac hot input (L) and said ac neutral input (N) and charged by a voltage of a second polarity, which is opposite in phase to the voltage of the first polarity, and discharged by a surge between said ac hot input (L) and said ac neutral input (N) with said first polarity;

a second amplifying circuit (15) connected between said second energy storage element (14), said ac hot input (L) and said ac neutral input (N) for generating a second amplified current for amplifying based on said discharging of said second energy storage element (14);

a second turn-off circuit (16) connected between the second amplifying circuit (15) and the second transistor (M1) for turning off the second transistor (M1) using the second amplifying current.

8. The active rectifier circuit according to claim 7, wherein the second turn-off circuit (16) comprises a pump circuit connected between the second amplifying circuit and the control electrode of the second transistor for pumping charge from the control electrode of the second transistor with the second amplifying current to turn off the second transistor.

9. An active rectifier circuit according to claim 7, characterized in that said second transistor (M1) is turned on at a voltage of said second polarity to connect said ac live input (L) to the positive pole of said dc output, said first transistor (M4) being turned off at said voltage of said second polarity, said second polarity being positive polarity of said ac live input (L).

10. An active rectifier circuit according to claim 9, characterized in that said first transistor (M4) has a body diode forward biased from said ac neutral input (N) to the positive pole of said dc output, said body diode of said first transistor (M4) being capable of being turned on by a surge of said first polarity between said ac hot input (L) and said ac neutral input (N);

but the second turn-off circuit (16) turns off the second transistor (M1) to avoid the surge from passing through the second transistor (M1) to avoid shorting the ac hot input (L) and the ac neutral input (N).

11. An active rectifier circuit according to claim 7, characterized in that the second energy storage element (14) comprises a second capacitance (C3) connected between the ac live input (L) and the ac neutral input (N).

12. An active rectifying circuit according to claim 11, characterized in that a first end of said second capacitor (C3) is connected to said ac neutral input (N), a second pole of said second capacitor (C3) is connected to said ac hot input (L), and said active rectifying circuit further comprises a second unidirectional element (D4), said second unidirectional element (D4) being adapted to unidirectional allow a voltage of said second polarity to charge said second capacitor (C3);

the second amplifying circuit (15) comprises a second darling circuit (Q3, Q4), the base of the second darling circuit (Q3, Q4) is connected to the second pole of the second capacitor (C3), the emitter is connected to the ac hot input (L), for unidirectionally allowing a surge of the first polarity to discharge the second capacitor (C3), and the collector is connected to the control pole of the second transistor (M1) through the second shut-off circuit (16).

13. The active rectifier circuit of claim 7, wherein the first energy storage element and the second energy storage element include capacitances that are parasitic capacitances of discrete device capacitances or diodes.

14. An LED driver comprising an active rectifying circuit according to any one of claims 1 to 13.

15. An LED lighting device comprising the LED driver of claim 14.