TW201909527A - Power supply - Google Patents

Abstract

A power supply includes a rectifying circuit, a power converting circuit, and a snubber circuit. The rectifying circuit is configured to convert an ac input voltage to a first dc voltage. The power converting circuit is electrically coupled to the rectifying circuit at a node. The power converting circuit includes a switching element and is configured to convert the first dc voltage to a second dc voltage by selectively turning on or off the switching element. The snubber circuit is electrically coupled to the rectifying circuit and the power converting circuit at the node. When the first dc voltage is higher than a limiting level, the snubber circuit is configured to absorb the electricity power to prevent the voltage across the switching element from exceeding a safety upper limit.

Description

Power Supplier

This case relates to a power supply, and in particular to a power supply with lightning surge protection capability.

Recently, many electronic products and drive circuits are powered by a switched power supply. When the system is struck by lightning, the instantaneous high voltage surge voltage is easily generated in the system, which in turn affects the operation of the switching power supply.

Since the lightning surge capability is closely related to the reliability of electronic equipment, how to improve the lightning surge resistance of the power supply to improve the power supply stability and provide good power quality is an important issue in the current related technical field. Research topics.

One aspect of the case is a power supply. The power supply includes a rectifier circuit, a power conversion circuit, and a buffer circuit. The rectifier circuit is configured to convert the AC input voltage into a first DC voltage. The power conversion circuit is electrically coupled to the rectifier circuit at the node. The power conversion circuit includes a switching element and converts the first DC voltage to a second DC voltage by selectively turning the switching element on or off. The buffer circuit is electrically coupled to the rectifier circuit and the power conversion circuit at the node. When the first DC voltage is greater than the limit level, the snubber circuit is used to absorb power to prevent the voltage across the switching element from exceeding the safety upper limit.

In some embodiments of the present invention, the buffer circuit includes a transient voltage suppressor and a first diode, wherein the first diode is reversely connected in series to the transient voltage suppressor, and when the first DC voltage is greater than the limit level, the instantaneous The state voltage suppressor is turned on and clamped across the voltage across the two ends, and the first diode is turned on.

In some embodiments of the present invention, the anode end of the transient voltage suppressor is electrically coupled to the anode end of the first diode, and the cathode end of the transient voltage suppressor is electrically coupled to the node.

In some embodiments of the present invention, the buffer circuit further includes an energy storage unit. The energy storage unit is electrically coupled to the cathode end of the first diode to absorb power from the transient voltage suppressor and the first diode that are transmitted from the node when the first DC voltage is greater than the limit level.

In some embodiments of the present invention, the energy storage unit includes a capacitor unit and a resistor unit. The capacitor unit is electrically coupled between the cathode end of the first diode and the ground to absorb power. The resistor unit is electrically coupled to the capacitor unit in parallel to form a discharge path with the capacitor unit to consume power.

In some embodiments of the present invention, the resistor unit includes a plurality of resistors electrically coupled to each other.

In some embodiments of the present invention, the power conversion circuit includes a flyback power converter for converting the first DC voltage to the second DC voltage.

In some embodiments of the present invention, the power supply further includes a clamp circuit. The clamp circuit is electrically coupled to the rectifier circuit for clamping the AC input voltage to the clamp voltage when the surge voltage is generated.

In some embodiments of the present invention, the clamp circuit includes a varistor. When a surge voltage is generated, a discharge current flows through the varistor to clamp the AC input voltage to the clamp voltage.

Another aspect of the present case is a power supply. The power supply includes a rectifier circuit, a power conversion circuit, a transient voltage suppressor, a first diode, a capacitor unit, and a resistor unit. The rectifier circuit is configured to convert the AC input voltage into a first DC voltage. The power conversion circuit is electrically coupled to the rectifier circuit at the node for converting the first DC voltage to the second DC voltage. The cathode end of the transient voltage suppressor is electrically coupled to the node. The anode end of the first diode is electrically coupled to the anode terminal of the transient voltage suppressor. The capacitor unit is electrically coupled between the cathode end of the first diode and the ground. The resistor unit is electrically coupled to the capacitor unit in parallel.

In some embodiments of the present invention, when the first DC voltage is greater than the limit level, the first diode is turned on, and the transient voltage suppressor is turned on correspondingly and clamps the voltage across the ends.

In some embodiments of the present invention, when the first DC voltage is greater than the limit level, the capacitor unit is configured to transmit power to the first diode through the turned-on transient voltage suppressor.

In some embodiments of the present invention, the resistor unit is configured to form a discharge path with the capacitor unit to consume power absorbed by the capacitor unit.

In some embodiments of the present invention, the power supply further includes a clamp circuit. The clamp circuit is electrically coupled to the rectifier circuit for clamping the AC input voltage to the clamp voltage when the surge voltage is generated.

In some embodiments of the present invention, the clamp circuit includes a varistor. When a surge voltage is generated, a discharge current flows through the varistor to clamp the AC input voltage to the clamp voltage.

In summary, the case provides a buffer circuit after the rectifier circuit to ensure that the power supply maintains high power and low harmonic components under normal operation, and is absorbed by the buffer circuit when lightning or other surge voltage is generated. Excessive power, avoiding energy being injected into the power conversion circuit, causing abnormal circuit operation or component damage.

The embodiments are described in detail below to better understand the aspects of the present invention, but the embodiments are not intended to limit the scope of the disclosure, and the description of the structural operation is not limited. The order in which they are performed, any device that is recombined by components, produces equal devices, and is covered by this disclosure. In addition, according to industry standards and practices, the drawings are only for the purpose of assisting the description, and are not drawn according to the original size. In fact, the dimensions of the various features may be arbitrarily increased or decreased for convenience of explanation. In the following description, the same elements will be denoted by the same reference numerals for explanation.

The terms used in the entire specification and the scope of the patent application, unless otherwise specified, generally have the ordinary meaning of each term used in the field, the content disclosed herein, and the particular content. Certain terms used to describe the disclosure are discussed below or elsewhere in this specification to provide additional guidance to those skilled in the art in the description of the disclosure.

In addition, the terms "including", "including", "having", "containing", and the like, as used herein, are all open terms, meaning "including but not limited to". Further, "and/or" as used herein includes any one or combination of one or more of the associated listed items.

As used herein, when an element is referred to as "connected" or "coupled", it may mean "electrically connected" or "electrically coupled". "Connected" or "coupled" can also be used to indicate that two or more components operate or interact with each other. In addition, although the terms "first", "second", and the like are used herein to describe different elements, the terms are used only to distinguish the elements or operations described in the same technical terms. The use of the term is not intended to be a limitation or a

Please refer to Figure 1. FIG. 1 is a schematic diagram of a power supply 100 according to some embodiments of the present disclosure. For example, in some embodiments, the power supply 100 can provide the power supply required by the LED driver. As shown in FIG. 1, in some embodiments, the power supply 100 includes a rectifier circuit 120, a buffer circuit 140, and a power conversion circuit 160. The power conversion circuit 160 is electrically coupled to the output of the rectifier circuit 120 at the node N1. The buffer circuit 140 is also electrically coupled to the rectifier circuit 120 and the power conversion circuit 160 at the node N1.

As shown in FIG. 1, the rectifier circuit 120 is for converting the AC input voltage Vac into a DC voltage Vin. For example, in some embodiments, the rectifier circuit 120 can be a bridge rectifier circuit, including a bridge circuit composed of diodes D1, D2, D3, and D4, and a filter capacitor Cin. Specifically, the anode end of the diode D1 is electrically coupled to the first input end of the AC input voltage Vac, and the cathode end of the diode D1 is electrically coupled to the first end of the filter capacitor Cin. The anode end of the diode D2 is electrically coupled to the second end of the filter capacitor Cin, and the cathode end of the diode D2 is electrically coupled to the anode end of the diode D1. The anode end of the diode D3 is electrically coupled to the second input end of the AC input voltage Vac, and the cathode end of the diode D3 is electrically coupled to the first end of the filter capacitor Cin. The anode end of the diode D4 is electrically coupled to the second end of the filter capacitor Cin, and the cathode end of the diode D4 is electrically coupled to the anode end of the diode D3.

Thereby, the rectifier circuit 120 can receive the AC input voltage Vac, rectify the AC input voltage Vac through the diodes D1, D2, D3, and D4, and filter the rectified voltage signal through the filter capacitor Cin to output DC voltage Vin.

In some embodiments, the power conversion circuit 160 is configured to convert the DC voltage Vin into a DC voltage Vo. For example, power conversion circuit 160 can include a switched power conversion architecture including switching element S1. The power conversion circuit 160 selectively turns on or off the switching element S1 by a Pulse Width Modulation (PWM) signal to convert the DC voltage Vin into a DC voltage Vo. Thereby, the voltage level of the output DC voltage Vo can be adjusted by appropriately adjusting the duty cycle of the pulse width modulation signal. In various embodiments, the switching element S1 can be a variety of transistors such as a Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET), a bipolar junction transistor (BJT), and the like. The switch is implemented, but this case is not limited to this.

In the embodiment shown in FIG. 1, the power conversion circuit 160 may include a fly-back power converter to convert the DC voltage Vin into a DC voltage Vo. Specifically, the power conversion circuit 160 includes a switching element S1, a primary winding Np of the transformer T1, a secondary winding Ns, a diode D5, and an output capacitor Co.

Structurally, the first end of the primary winding Np is electrically coupled to the node N1. The second end of the primary winding Np is electrically coupled to the first end of the switching element S1. The second end of the switching element S1 is electrically coupled to the second end of the filter capacitor Cin. The control terminal of the switching element S1 is configured to receive a pulse width modulation signal. The first end of the secondary winding Ns is electrically coupled to the anode end of the diode D5. The cathode end of the diode D5 is electrically coupled to the first end of the output capacitor Co. The second end of the secondary winding Ns is electrically coupled to the second end of the output capacitor Co.

When the switching element S1 is turned on, the primary current flows through the primary winding Np, and the electrical energy is stored on the primary winding Np. Since the primary winding Np and the secondary winding Ns are opposite in polarity to each other, the diode D5 operates at the reverse bias and is not turned on, and the output capacitor Co is used to provide the power output required by the subsequent circuit. When the switching element S1 is turned off, the primary current drops to zero, the polarity on the winding is reversed, so that the diode D5 is turned on, and the energy stored in the transformer T1 is output through the diode D5 to the output capacitor Co and thereafter. Stage circuit.

It should be noted that the power conversion circuit 160 shown in FIG. 1 is for illustrative purposes only and is not intended to limit the present invention. The power conversion circuit 160 can also be implemented by a flyback power converter of other architectures or a variety of different types of switched power converters.

In the event of power-on, abnormal use, or lightning strikes, inrush currents can occur in the system and can have a significant impact on the normal use of the power circuit. For example, when a lightning strike occurs, the DC voltage Vin may rise sharply, and the energy generated by the lightning strike is poured into the power conversion circuit 160, thereby causing the switching element S1 to fail to operate normally, resulting in abnormal operation of the power conversion circuit 160. In severe cases, the electronic components in the power conversion circuit 160 may even be damaged.

In order to avoid the above situation, in some embodiments, when the DC voltage Vin is greater than the limit level, the buffer circuit 140 is configured to absorb power to prevent the voltage across the switching element S1 in the power conversion circuit 160 from being greater than the safety upper limit. S1 damage. In other words, current does not flow through the snubber circuit 140 under normal operating conditions. In contrast, when a surge voltage and a surge current are generated such that the DC voltage Vin is greater than the limit level, the buffer circuit 140 automatically forms a discharge loop to absorb excess power. Thereby, the energy flowing into the power conversion circuit 160 can be reduced to prevent the surge voltage and the surge current from damaging the power conversion circuit 160 or the subsequent circuit.

To further illustrate the operation of the buffer circuit 140, please refer to FIG. FIG. 2 is a schematic diagram of a power supply 100 according to some embodiments of the present disclosure. In the second embodiment, similar elements related to the embodiment of FIG. 1 are denoted by the same reference numerals for ease of understanding, and the specific principles of the similar elements have been described in detail in the previous paragraph, if not between the elements of FIG. Those who have a cooperative operation relationship and need to introduce them will not repeat them here.

As shown in FIG. 2, in some embodiments, the buffer circuit 140 includes a Transient Voltage Suppressor (TVS) ZD1, a diode D6, and an energy storage unit 142. For example, the transient voltage suppressor ZD1 can be a unidirectional TVS diode. Structurally, the anode terminal of the transient voltage suppressor ZD1 is electrically coupled to the anode terminal of the diode D6. The cathode end of the transient voltage suppressor ZD1 is electrically coupled to the node N1. The energy storage unit 142 is electrically coupled between the cathode end of the diode D6 and the ground end of the primary side. In other words, the diode D6 is reversely connected in series to the transient voltage suppressor ZD1.

When the DC voltage Vin is greater than the limit level, the transient voltage suppressor ZD1 is turned on correspondingly and clamped across the voltage across the two ends, and the diode D6 is turned on. Specifically, when the DC voltage Vin is greater than the limit level, the voltage across the transient voltage suppressor ZD1 may exceed the Breakdown Voltage. At this point, the transient voltage suppressor ZD1 turns on and acts as a clamp, clamping across the voltage across the clamp to suppress excessive voltages above its sudden collapse level. Thereby, the current can flow into the energy storage unit 142 via the forward-conducting diode D6.

In this way, the energy storage unit 142 can be used to absorb power from the transient voltage suppressor ZD1 and the diode D6 that are turned on from the node N1 when the DC voltage Vin is greater than the limit level.

In addition, since the diode D6 and the transient voltage suppressor ZD1 are connected in reverse series, the power supply is in a normal state (that is, when the DC voltage Vin is not greater than the limit level), and the transient voltage suppressor ZD1 itself is utilized. The high-impedance characteristic, the snubber circuit 140 does not operate; and when the dc voltage Vin is greater than the limit level, when the snubber circuit 140 is activated, there is no reverse leakage current from the energy storage unit 142 due to the presence of the diode D6. Conversion circuit 160. Thereby, it can be ensured that the buffer circuit 140 does not affect the operation of the rectifier circuit 120 and the power conversion circuit 160. In this way, the power supply 100 can maintain the original high power factor (PF) and the Total Harmonic Distortion (THD).

Please refer to Figure 3. FIG. 3 is a schematic diagram of a power supply 100 according to some embodiments of the present disclosure. In the third embodiment, similar elements to those of the first embodiment and the second embodiment are denoted by the same reference numerals for easy understanding, and the specific principles of the similar elements have been explained in detail in the previous paragraphs, if not the second Those who have a cooperative operation relationship between the components of the figure and the third figure are necessary to introduce them, and will not be described here.

In some embodiments, the power supply 100 further includes a clamp circuit 180, as compared to the embodiment shown in FIG. The clamping circuit 180 is electrically coupled to the rectifier circuit 120 .

Specifically, in the embodiment shown in FIG. 3, the clamp circuit 180 is connected across the AC input voltage Vac and is used to clamp the AC input voltage Vac to a clamp voltage when the surge voltage is generated. For example, the clamp circuit 180 can include a varistor Z1. The resistance value of the varistor Z1 changes with the voltage across the ends. The varistor Z1 has a high impedance value at a normal operating voltage. On the other hand, when a surge voltage is generated, the impedance value of the varistor Z1 is lowered and turned on. Thereby, the discharge current can flow through the varistor Z1 to clamp the AC input voltage Vac to the clamp voltage. In this way, by the cooperative operation of the clamp circuit 180 and the buffer circuit 140, excessive voltage can be further prevented from being poured into the power conversion circuit 160.

For example, in some embodiments, the varistor Z1 may be selected from a varistor having an AC rated voltage of 350 VAC in consideration of the rated input and output voltages required by the power supply 100. The varistor Z1 described above can provide a maximum clamping voltage of approximately 925V. Thereby, when the surge voltage is generated, the power supply 100 can ensure that the voltage level of the DC voltage Vin is not higher than 925V.

On the other hand, the transient voltage suppressor ZD1 can select a TVS diode with a collapse level of about 400V. As a result, the maximum cross-over pressure at both ends of the energy storage unit 142 is not higher than about 525V. Thereby, the withstand voltage value required for the electronic device in the energy storage unit 142 can be reduced.

Please refer to Figure 4. FIG. 4 is a schematic diagram of a buffer circuit 140 according to some embodiments of the present disclosure. As shown in FIG. 4, in some embodiments, the energy storage unit 142 in the buffer circuit 140 includes a capacitor unit C1 and a resistor unit R1. Structurally, the capacitor unit C1 is electrically coupled between the cathode end and the ground of the diode D6 for absorbing power. The resistor unit R1 is electrically coupled to the capacitor unit C1 in parallel to form a discharge path with the capacitor unit C1 to consume power absorbed by the capacitor unit C1.

Thereby, after clamping by the clamp circuit 180 and the transient voltage suppressor ZD1, the remaining lightning strike energy can be absorbed by the capacitor unit C1 connected in series with the transient voltage suppressor ZD1. In other words, when the DC voltage Vin is greater than the limit level, the capacitor unit C1 transmits power through the turned-on transient voltage suppressor ZD1 and the diode D6. Then, the residual voltage on the capacitor unit C1 can be consumed by the RC loop formed by the capacitor unit C1 and the resistor unit R1. In other words, the resistor unit R1 forms a discharge path with the capacitor unit C1 to dissipate the power absorbed by the capacitor unit C1 to avoid voltage saturation of the capacitor unit C1. In this way, the energy storage unit 142 can consume residual lightning energy through the capacitor unit C1 and the resistor unit R1 connected in parallel with each other, thereby achieving lightning strike protection and anti-surge voltage and surge current effects.

It should be noted that in some embodiments, the capacitor unit C1 and the resistor unit R1 may respectively include a plurality of capacitors and resistors connected in series or in parallel with each other. Please refer to Figure 5. FIG. 5 is a schematic diagram of a buffer circuit 140 according to other embodiments of the present invention. As shown in FIG. 5, in some embodiments, the resistor unit R1 may include a plurality of resistors Ra to Rd electrically coupled to each other. For example, the resistors Rc, Rd may be connected in series with each other and in parallel with the resistors Ra, Rb and the capacitor unit C1.

Thereby, the energy storage unit 142 can be implemented by selecting appropriate capacitors and resistors according to the circuit layout and the actual needs of the circuit design and cost considerations. In other words, the energy storage unit 142 shown in the various embodiments of the present invention is only one of the possible implementation modes of the present invention, and is not intended to limit the present case.

In summary, in the present embodiment, the buffer circuit is disposed after the rectifier circuit in each embodiment to ensure that the power supply maintains high power and low harmonic components under normal operation, and when lightning or other surge voltage is generated. The snubber circuit absorbs excess power to prevent energy from being injected into the power conversion circuit, causing abnormal operation of the circuit or component damage.

The present disclosure has been disclosed in the above embodiments, and is not intended to limit the disclosure, and the present disclosure may be variously modified and retouched without departing from the spirit and scope of the present disclosure. The scope of protection of the content is subject to the definition of the scope of the patent application.

100‧‧‧Power supply

120‧‧‧Rectifier circuit

140‧‧‧buffer circuit

142‧‧‧ Energy storage unit

160‧‧‧Power conversion circuit

180‧‧‧Clamp circuit

T1‧‧‧ transformer

Np‧‧‧ primary winding

Ns‧‧‧ secondary winding

S1‧‧‧ switching components

D1, D2, D3, D4, D5, D6‧‧‧ diodes

Cin‧‧‧Filter Capacitor

Co‧‧‧ output capacitor

N1‧‧‧ node

ZD1‧‧‧Transient Voltage Suppressor

Z1‧‧‧ varistor

C1‧‧‧Capacitor unit

R1‧‧‧resistance unit

Ra～Rd‧‧‧Resistors

Vac‧‧‧AC input voltage

Vin, Vo‧‧‧ DC voltage

FIG. 1 is a schematic diagram of a power supply according to some embodiments of the present disclosure. FIG. 2 is a schematic diagram of a power supply according to some embodiments of the present disclosure. FIG. 3 is a schematic diagram of a power supply according to some embodiments of the present disclosure. FIG. 4 is a schematic diagram of a buffer circuit according to some embodiments of the present invention. FIG. 5 is a schematic diagram of a buffer circuit according to other embodiments of the present invention.

Claims (15)

A power supply, comprising: a rectifier circuit for converting an AC input voltage into a first DC voltage; a power conversion circuit electrically coupled to the rectifier circuit at a node, wherein the power conversion circuit includes a a switching element that selectively turns the switching element on or off to convert the first DC voltage into a second DC voltage; and a buffer circuit electrically coupled to the rectifier circuit and the power conversion The circuit, wherein when the first DC voltage is greater than a limit level, the buffer circuit is configured to absorb power to prevent a voltage across the switching element from being greater than a safe upper limit. The power supply of claim 1, wherein the buffer circuit comprises a transient voltage suppressor and a first diode, wherein the first diode is reversely connected in series to the transient voltage suppressor, when the first When a DC voltage is greater than the limit level, the transient voltage suppressor is turned on and clamped across the voltage across the two ends, and the first diode is turned on. The power supply device of claim 2, wherein an anode terminal of the transient voltage suppressor is electrically coupled to an anode terminal of the first diode, and a cathode terminal of the transient voltage suppressor is electrically coupled At this node. The power supply device of claim 3, wherein the buffer circuit further comprises an energy storage unit, the energy storage unit is electrically coupled to a cathode end of the first diode for the first DC voltage The transient voltage suppressor that is turned on from the node when the limit is greater than the limit level absorbs power from the first diode. The power supply unit of claim 4, wherein the energy storage unit comprises: a capacitor unit electrically coupled between the cathode end and a ground end of the first diode to absorb power; A resistor unit is electrically coupled to the capacitor unit in parallel to form a discharge path with the capacitor unit to consume power. The power supply of claim 5, wherein the resistor unit comprises a plurality of resistors electrically coupled to each other. The power supply of claim 1, wherein the power conversion circuit comprises a flyback power converter for converting the first DC voltage to the second DC voltage. The power supply device of claim 1, further comprising a clamp circuit electrically coupled to the rectifier circuit for clamping the AC input voltage to a clamp when a surge voltage is generated Voltage. The power supply device of claim 8, wherein the clamp circuit comprises a varistor, and when the surge voltage is generated, a discharge current flows through the varistor to clamp the AC input voltage to the tong Bit voltage. A power supply, comprising: a rectifier circuit for converting an AC input voltage into a first DC voltage; a power conversion circuit electrically coupled to the rectifier circuit at a node for using the first DC The voltage is converted into a second DC voltage; a transient voltage suppressor, a cathode end of the transient voltage suppressor is electrically coupled to the node; a first diode, an anode terminal of the first diode Is electrically coupled to an anode terminal of the transient voltage suppressor; a capacitor unit electrically coupled between a cathode end and a ground end of the first diode; and a resistor unit electrically connected in parallel The capacitor unit is coupled to the capacitor unit. The power supply device of claim 10, wherein when the first DC voltage is greater than a limit level, the first diode is turned on, and the transient voltage suppressor is turned on and clamped across the voltage across the clamp. . The power supply of claim 10, wherein when the first DC voltage is greater than a limit level, the capacitor unit is configured to transmit power to the first diode through the turned-on transient voltage suppressor. The power supply of claim 12, wherein the resistor unit is configured to form a discharge path with the capacitor unit to consume power absorbed by the capacitor unit. The power supply device of claim 10, further comprising a clamp circuit electrically coupled to the rectifier circuit for clamping the AC input voltage to a clamp when a surge voltage is generated Voltage. The power supply of claim 14, wherein the clamp circuit comprises a varistor, and when the surge voltage is generated, a discharge current flows through the varistor to clamp the AC input voltage to the tong Bit voltage.