CN111934554B - Power supply conversion device - Google Patents
Power supply conversion device Download PDFInfo
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- CN111934554B CN111934554B CN201910394176.2A CN201910394176A CN111934554B CN 111934554 B CN111934554 B CN 111934554B CN 201910394176 A CN201910394176 A CN 201910394176A CN 111934554 B CN111934554 B CN 111934554B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
- H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
- H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/0096—Means for increasing hold-up time, i.e. the duration of time that a converter's output will remain within regulated limits following a loss of input power
Abstract
The invention provides a power conversion device, which comprises a transformer, a power switch, a pulse width modulation signal generator, an energy storage element and a power circuit. The primary winding of the transformer receives an input voltage from an external power source. An auxiliary winding of the transformer provides an auxiliary voltage. The power switch is coupled to the primary side winding. The PWM signal generator generates a PWM signal to control the power switch to be turned on or off. The energy storage element is coupled with a power supply end of the pulse width modulation signal generator. The power supply circuit supplies power to the pulse width modulation signal generator and charges the energy storage element according to the auxiliary voltage. When the voltage of the energy storage element is greater than or equal to the critical voltage, the power supply circuit stores the standby power according to the auxiliary voltage. When the external power supply stops providing the input voltage, the power supply circuit supplies power to the pulse width modulation signal generator and charges the energy storage element according to the standby power.
Description
Technical Field
The present invention relates to a power supply device, and more particularly, to a power supply switching device capable of prolonging a holding time of an output voltage.
Background
The power conversion device (power conversion apparatus) can convert an input voltage provided by an external power source into a dc voltage suitable for various electronic devices. Therefore, the power conversion device is widely used in electronic devices such as computers, office automation equipment, industrial control equipment, and communication equipment.
In a power conversion apparatus based on Pulse Width Modulation (PWM) control, a primary side of the power conversion apparatus generally has a power switch and a PWM control chip. The pulse width modulation control chip is used for controlling the on-off of the power switch, so that a transformer in the power conversion device can transfer the electric energy stored at the primary side to the secondary side of the power conversion device and output direct-current voltage to the electronic device. In addition, the auxiliary winding of the transformer can provide the power required by the operation of the pwm control chip through the power supply terminal of the pwm control chip, and the power supply terminal of the pwm control chip is usually provided with a voltage stabilizing capacitor.
Generally, after a power source of a power conversion device is powered off, the power conversion device needs to continuously output a dc voltage to an electronic device for a hold-up time (hold-up time) to reduce an influence on the electronic device due to an instantaneous power off. However, since the voltage-stabilizing capacitor of the pwm control chip is usually very small, when the power conversion device is suddenly powered off, the pwm control chip is powered off to stop controlling the power switch to turn on or off, so that the power conversion device stops outputting the dc voltage in a very short time. Therefore, the conventional power conversion device usually has a problem of insufficient holding time, thereby reducing the stability of the electronic device in operation.
Disclosure of Invention
In view of the above, the present invention provides a power conversion apparatus, which can supply power to a pwm signal generator according to backup power stored in the power conversion apparatus when the power conversion apparatus is powered off, so as to prolong a sustain time of a continuous output voltage of the power conversion apparatus.
The power conversion device comprises a transformer, a first power switch, a pulse width modulation signal generator, an energy storage element and a power circuit. The transformer has a primary winding and an auxiliary winding. The primary winding is used for receiving an input voltage from an external power supply. The auxiliary winding is used for providing an auxiliary voltage. The first power switch is coupled to the primary winding and controlled by a pulse width modulation signal. The pwm signal generator is coupled to the first power switch for generating a pwm signal to control the on/off of the first power switch. The energy storage element is coupled with a power supply end of the pulse width modulation signal generator. The power circuit is coupled to the auxiliary winding, a power end of the PWM signal generator and the energy storage element, and is used for supplying power to the PWM signal generator and charging the energy storage element according to the auxiliary voltage. When the voltage of the energy storage element is greater than or equal to the critical voltage, the power supply circuit stores the standby power according to the auxiliary voltage. When the external power supply stops providing the input voltage, the power supply circuit supplies power to the pulse width modulation signal generator and charges the energy storage element according to the standby power.
Based on the above, the power conversion apparatus provided by the present invention can supply power to the pwm signal generator according to the backup power stored in the power conversion apparatus when the power conversion apparatus is stopped. Therefore, after the power conversion device stops supplying power, the maintaining time of the continuous output voltage of the power conversion device can be prolonged.
In order to make the aforementioned and other features and advantages of the invention more comprehensible, embodiments accompanied with figures are described in detail below.
Drawings
Fig. 1 is a block diagram of a power conversion apparatus according to an embodiment of the invention.
Fig. 2 is a block diagram of a power circuit according to an embodiment of the invention.
Fig. 3 is a schematic circuit diagram of a charging circuit and a power backup circuit according to an embodiment of the invention.
Fig. 4 is a schematic circuit diagram of a charging circuit and a power backup circuit according to another embodiment of the invention.
[ notation ] to show
100: power supply conversion device
120: pulse width modulation signal generator
140: energy storage element
160. 160': power supply circuit
180: rectifying circuit
262: charging circuit
264. 464: power backup circuit
2641. 4641, 4642: energy storage circuit
CA 1: auxiliary capacitor
CA2, CA21, CA 22: energy storage capacitor
CIN: input capacitance
CS1, CS 2: control signal
CSG: control signal group
CT: control terminal
D21, D22, D41, D42, D421, D422: diode with a high-voltage source
EE: backup power
GND 1: grounding terminal
INT: input terminal
N1: first node
Na: auxiliary winding
Np: primary side winding
Ns: secondary side winding
OT: output end
PVCC: power supply terminal
Q1, Q2, Q21, Q22: power switch
SP: pulse width modulation signal
TR: transformer device
V1: first voltage
VA: auxiliary voltage
VCC, VS1, VS 2: voltage of
VIN: input voltage
VO: output voltage
VT: critical voltage
Detailed Description
In order that the present disclosure may be more readily understood, the following specific examples are given as illustrative of the invention which may be practiced in various ways. Further, wherever possible, the same reference numbers will be used throughout the drawings and the description to refer to the same or like parts.
Fig. 1 is a block diagram of a power conversion apparatus 100 according to an embodiment of the invention. Referring to fig. 1, the power conversion apparatus 100 may include a transformer TR, a power switch Q1, a pwm signal generator 120, an energy storage device 140, and a power circuit 160, but the invention is not limited thereto. In an embodiment of the invention, the power conversion apparatus 100 may further include an input capacitor CIN and a rectifying circuit 180.
The transformer TR has a primary winding Np, a secondary winding Ns, and an auxiliary winding Na. The primary winding Np is used for receiving an input voltage VIN from an external power source. The secondary winding Ns is coupled to the rectifying circuit 180 for providing the output voltage VO to the load. The auxiliary winding Na is used to provide an auxiliary voltage VA.
The input capacitor CIN is coupled between a first terminal (e.g., common-polarity terminal) of the primary winding Np and the ground terminal GND 1. The input capacitor CIN may store electrical energy when the external power source provides the input voltage VIN to the power conversion apparatus 100. When the external power supply stops providing the input voltage VIN to the power conversion apparatus 100, the electric energy stored in the input capacitor CIN may discharge energy to the secondary winding Ns.
The power switch Q1 is coupled between a second end (e.g., an end-of-common (non-dotted) end) of the primary winding Np and the ground GND1, and is controlled by the pwm signal SP. The pwm signal generator 120 is coupled to the power switch Q1, and is configured to generate a pwm signal SP to control the on/off of the power switch Q1, so that the transformer TR can transfer the electric energy stored in the primary winding Np to the secondary winding Ns, and provide the output voltage VO to the load through the rectifier circuit 180. In an embodiment of the present invention, the pwm signal generator 120 may be implemented by a hardware circuit such as a micro-controller (micro-controller) or an Application Specific Integrated Circuit (ASIC) or a Programmable Logic Device (PLD) or a Field Programmable Gate Array (FPGA), but is not limited thereto.
The energy storage device 140 is coupled between the power supply terminal PVCC of the pwm signal generator 120 and the ground terminal GND1 for stabilizing the voltage of the power supply terminal PVCC. In an embodiment of the present invention, the energy storage element 140 may be implemented by a capacitor, but is not limited thereto.
The power circuit 160 is coupled to the auxiliary winding Na, the power terminal PVCC of the pwm signal generator 120, and the energy storage element 140. The power circuit 160 can supply power to the pwm signal generator 120 and charge the energy storage element 140 according to the auxiliary voltage VA.
Specifically, when the voltage VCC of the energy storage device 140 (i.e., the voltage of the power supply terminal PVCC of the pwm signal generator 120) is charged to be greater than or equal to the threshold voltage VT, the power circuit 160 can store the backup power EE according to the auxiliary voltage VA. In addition, when the external power supply stops providing the input voltage VIN to the power conversion apparatus 100, the power circuit 160 can supply power to the pwm signal generator 120 and charge the energy storage device 140 according to the standby power EE. In this way, when the external power source stops supplying power to the power conversion apparatus 100, the backup power EE stored in the power circuit 160 can prolong the time that the pwm signal generator 120 is powered, so as to prolong the hold time (hold-up time) that the power conversion apparatus 100 continuously provides the output voltage VO.
In an embodiment of the invention, the pwm signal generator 120 can detect the voltage VCC of the energy storage element 140 through the power supply terminal PVCC. When the voltage VCC of the energy storage device 140 is greater than or equal to the threshold voltage VT, the pwm signal generator 120 may output the control signal group CSG to the power circuit 160, so that the power circuit 160 stores the backup power EE according to the auxiliary voltage VA in response to the control signal group CSG.
In an embodiment of the present invention, the pwm signal generator 120 detects the voltage VS of the standby power EE. When the voltage VS of the backup power EE is greater than or equal to the threshold voltage VT, it indicates that the power circuit 160 has completed storing the backup power EE, so the pwm signal generator 120 stops outputting the control signal group CSG to the power circuit 160.
In an embodiment of the invention, the threshold voltage VT is a minimum voltage required for the pwm signal generator 120 to operate normally, but the invention is not limited thereto.
Fig. 2 is a block diagram of a power circuit 160 according to an embodiment of the invention. For convenience of illustration, fig. 2 also shows the coupling relationship between the power circuit 160 and the auxiliary winding Na, the pwm signal generator 120 and the energy storage element 140. Referring to fig. 1 and fig. 2, the power circuit 160 includes a charging circuit 262 and a power backup circuit 264. The charging circuit 262 is coupled to the auxiliary winding Na, the power source terminal PVCC of the pwm signal generator 120 and the energy storage device 140. The charging circuit 262 rectifies and filters the auxiliary voltage VA to generate the first voltage V1, and powers the pwm signal generator 120 and charges the energy storage element 140 according to the first voltage V1.
The power backup circuit 264 is coupled to the charging circuit 262, the power source terminal PVCC of the pwm signal generator 120 and the energy storage device 140. When the voltage VCC of the energy storage device 140 (i.e., the voltage of the power source terminal PVCC of the pwm signal generator 120) is charged to be greater than or equal to the threshold voltage VT, the pwm signal generator 120 may output the control signal group CSG to the power backup circuit 264, so that the power backup circuit 264 stores the backup power EE based on the first voltage V1. In addition, the pwm signal generator 120 may detect the voltage VS of the standby power EE. When the voltage VS of the backup power EE is charged to be greater than or equal to the threshold voltage VT, it indicates that the power backup circuit 264 is fully charged, so the pwm signal generator 120 stops outputting the control signal group CSG to the power backup circuit 264. In addition, when the external power source stops providing the input voltage VIN, the power backup circuit 264 may power the pwm signal generator 120 and charge the energy storage device 140 according to the backup power EE, so as to prolong the time that the pwm signal generator 120 is powered.
Fig. 3 is a schematic circuit diagram illustrating the charging circuit 262 and the power backup circuit 264 of the power circuit 160 according to an embodiment of the invention. For convenience of illustration, fig. 3 also shows the auxiliary winding Na, the pwm signal generator 120, and the energy storage element 140. Please refer to fig. 1 and fig. 3. The charging circuit 262 includes a diode D21, a diode D22, and an auxiliary capacitor CA 1. A first terminal (e.g., a dotted terminal) of the auxiliary winding Na is coupled to the ground terminal GND 1. An anode terminal of the diode D21 is coupled to a second terminal (e.g., a different name terminal) of the auxiliary winding Na to receive the auxiliary voltage VA. The cathode terminal of the diode D21 is coupled to the first node N1 and provides the first voltage V1. An anode terminal of the diode D22 is coupled to the first node N1. The cathode terminal of the diode D22 is coupled to the power source terminal PVCC of the pwm signal generator 120 and the energy storage device 140. The first terminal of the auxiliary capacitor CA1 is coupled to the ground GND 1. The second terminal of the auxiliary capacitor CA1 is coupled to the first node N1.
The power backup circuit 264 may include a tank circuit 2641 and a diode D41. The energy storage circuit 2641 is connected in series between the charging circuit 262 and the anode terminal of the diode D41 for storing the backup power EE. The cathode terminal of the diode D41 is coupled to the power source terminal PVCC of the pwm signal generator 120 and the energy storage device 140.
In the present embodiment, the control signal group CSG includes a control signal CS 1. When the voltage VCC of the energy storage device 140 is greater than or equal to the threshold voltage VT, the pwm signal generator 120 outputs the control signal CS1 to the energy storage circuit 2641, and the energy storage circuit 2641 stores the electric energy as the backup power EE according to the first voltage V1 in response to the control signal CS 1. The pwm signal generator 120 can detect the voltage VS1 of the energy stored in the tank circuit 2641. When the voltage VS1 of the energy stored in the energy storage circuit 2641 is greater than or equal to the threshold voltage VT, the pwm signal generator 120 stops outputting the control signal CS1 to the energy storage circuit 2641, and the energy storage circuit 2641 finishes storing the energy. In addition, when the external power source stops providing the input voltage VIN, the energy storage circuit 2641 may supply the pwm signal generator 120 and charge the energy storage element 140 with the backup power EE through the diode D41.
More specifically, the tank circuit 2641 has an input INT, a control CT and an output OT. The input INT of the tank circuit 2641 is coupled to the charging circuit 262 to receive the first voltage V1. The output terminal OT of the tank circuit 2641 is coupled to the anode terminal of the diode D41 and the pwm signal generator 120. The control terminal CT of the tank circuit 2641 receives the control signal CS 1. In this embodiment, the energy storage circuit 2641 includes a power switch Q2, a diode D42, and an energy storage capacitor CA 2. The first terminal and the control terminal of the power switch Q2 are respectively used as the input terminal INT and the control terminal CT of the tank circuit 2641. An anode terminal of the diode D42 is coupled to the second terminal of the power switch Q2. A first terminal of the energy storage capacitor CA2 is coupled to a cathode terminal of the diode D42 as an output terminal OT of the energy storage circuit 2641. The second terminal of the energy storage capacitor CA2 is coupled to the ground GND 1.
The operation of the charging circuit 262 and the power backup circuit 264 of FIG. 3 will be described in detail. Please refer to fig. 1 and fig. 3 again. When the external power source starts to provide the input voltage VIN to the power conversion apparatus 100, the auxiliary winding Na may charge the auxiliary capacitor CA1 through the diode D21, and provide the first voltage V1 at the first node N1. Furthermore, the auxiliary winding Na may charge the energy storage element 140 via diodes D21, D22.
The pwm signal generator 120 can detect the voltage VCC of the energy storage element 140 through the power supply terminal PVCC. When the pwm signal generator 120 detects that the voltage VCC of the energy storage device 140 is charged to be greater than or equal to the threshold voltage VT, the pwm signal generator 120 may output the control signal CS1 with a logic high level to turn on the power switch Q2, so that the auxiliary winding Na starts to charge the energy storage capacitor CA2 through the diodes D21 and D42 as the backup power EE.
In addition, the pwm signal generator 120 may detect the voltage VS1 of the energy storage capacitor CA2 through the output terminal OT of the energy storage circuit 2641. When the voltage VS1 of the energy storage capacitor CA2 is greater than or equal to the threshold voltage VT, it indicates that the energy storage capacitor CA2 has been charged, so the pwm signal generator 120 can stop outputting the control signal CS1 or output the control signal CS1 with a logic low level to turn off the power switch Q2.
On the other hand, when the external power supply stops providing the input voltage VIN, the auxiliary winding Na will stop supplying power to the pwm signal generator 120 and charging the energy storage element 140, so that the voltage VCC of the energy storage element 140 drops. When the Voltage difference between the Voltage VS1 of the energy storage capacitor CA2 and the Voltage VCC of the energy storage element 140 is greater than the Cut-in Voltage (Cut-in Voltage, which is the lowest Voltage for turning on the diode D41) of the diode D41, the diode D41 is turned on, so that the electric energy (i.e., the backup power EE) stored in the energy storage capacitor CA2 can supply power to the pwm signal generator 120 and charge the energy storage element 140, so as to prolong the time for which the pwm signal generator 120 is supplied power, thereby prolonging the duration for which the power conversion device 100 continuously provides the output Voltage VO.
Incidentally, the relationship between the logic high level of the control signal CS1 and the on/off state of the power switch Q2 is only an example. It is well known to those skilled in the art that the relationship between the logic high and low level of the control signal CS1 and whether the power switch Q2 is turned on or off can be defined by a designer according to actual requirements.
Fig. 4 is a schematic circuit diagram illustrating the charging circuit 262 and the power backup circuit 464 of the power circuit 160', according to another embodiment of the invention. For convenience of illustration, fig. 4 also shows the auxiliary winding Na, the pwm signal generator 120, and the energy storage element 140. Referring to fig. 1, fig. 3 and fig. 4, the charging circuit 262 in fig. 4 is similar to the charging circuit 262 in fig. 3, so that the above description of fig. 3 can be referred to, and is not repeated herein.
In addition, compared to the power backup circuit 264 of fig. 3 having the diode D41 and the energy storage circuit 2641, the power backup circuit 464 of fig. 4 has the diode D41 and two energy storage circuits 4641 and 4642. In detail, the energy storage circuits 4641 and 4642 are serially connected and are serially connected between the charging circuit 262 and the anode terminal of the diode D41. The cathode terminal of the diode D41 is coupled to the power source terminal PVCC of the pwm signal generator 120 and the energy storage device 140.
In the present embodiment, the control signal group CSG may include control signals CS1 and CS 2. When the voltage VCC of the energy storage device 140 is greater than or equal to the threshold voltage VT, the pwm signal generator 120 outputs the control signals CS1 and CS2 to the energy storage circuits 4641 and 4642, respectively. The energy storage circuits 4641, 4642 may store electric energy according to the first voltage V1 as backup power EE in response to the control signals CS1, CS2, respectively. The pwm signal generator 120 may detect the voltages VS1, VS2 of the electrical energy stored by each of the tank circuits 4641, 4642. When the voltage VS2 of the electric energy stored in the energy storage circuit 4642 is greater than or equal to the threshold voltage VT, the pwm signal generator 120 stops outputting the corresponding control signal CS2 to the energy storage circuit 4642, and the energy storage circuit 4642 finishes storing the electric energy. Similarly, when the voltage VS1 of the power stored in the energy storage circuit 4641 is greater than or equal to the threshold voltage VT, the pwm signal generator 120 stops outputting the corresponding control signal CS1 to the energy storage circuit 4641, and the energy storage circuit 4641 finishes storing the power. In addition, when the external power source stops providing the input voltage VIN, the energy storage circuits 4641, 4642 may supply the pwm signal generator 120 and charge the energy storage element 140 with the backup power EE through the diode D41.
Further, each of the tank circuits 4641, 4642 has an input INT, a control CT, and an output OT. The input INT of the first tank circuit 4641 is coupled to the charging circuit 262 to receive the first voltage V1. The output terminal OT of the first tank 4641 is coupled to the input terminal INT of the second tank 4642 and the pwm signal generator 120. The output terminal OT of the second tank 4642 is coupled to the anode terminal of the diode D41 and the pwm signal generator 120.
The control terminal CT of the tank circuit 4641 receives the control signal CS1, and the control terminal CT of the tank circuit 4642 receives the control signal CS 2. In this embodiment, the energy storage circuit 4641 includes a power switch Q21, a diode D421 and an energy storage capacitor CA 21. The first terminal and the control terminal of the power switch Q21 are respectively used as the input terminal INT and the control terminal CT of the tank circuit 4641. An anode terminal of the diode D421 is coupled to a second terminal of the power switch Q21. A first terminal of the energy storage capacitor CA21 is coupled to the cathode terminal of the diode D421 to serve as the output terminal OT of the energy storage circuit 4641. The second terminal of the energy storage capacitor CA21 is coupled to the ground GND 1. Likewise, the energy storage circuit 4642 includes a power switch Q22, a diode D422, and an energy storage capacitor CA 22. The first terminal and the control terminal of the power switch Q22 are respectively used as the input terminal INT and the control terminal CT of the tank circuit 4642. The anode terminal of the diode D422 is coupled to the second terminal of the power switch Q22. A first terminal of the energy storage capacitor CA22 is coupled to a cathode terminal of the diode D422 as an output terminal OT of the energy storage circuit 4642. The second terminal of the energy storage capacitor CA22 is coupled to the ground GND 1.
Details of the operations of the charging circuit 262 and the power backup circuit 464 of fig. 4 are described below. Please refer to fig. 1 and fig. 4. When the external power source starts to provide the input voltage VIN to the power conversion apparatus 100, the auxiliary winding Na may charge the auxiliary capacitor CA1 through the diode D21, and provide the first voltage V1 at the first node N1. Furthermore, the auxiliary winding Na may charge the energy storage element 140 via diodes D21, D22.
The pwm signal generator 120 can detect the voltage VCC of the energy storage element 140 through the power supply terminal PVCC. When the pwm signal generator 120 detects that the voltage VCC of the energy storage device 140 is charged to be greater than or equal to the threshold voltage VT, the pwm signal generator 120 may output logic high control signals CS1 and CS2 to turn on the power switches Q21 and Q22, respectively, so that the auxiliary winding Na starts to charge the energy storage capacitors CA21 and CA22 through the diodes D21, D421 and D422 to be used as the backup power EE.
In addition, the pwm signal generator 120 may detect the voltage VS2 of the energy storage capacitor CA22 through the output terminal OT of the energy storage circuit 4642. When the voltage VS2 of the energy storage capacitor CA22 is greater than or equal to the threshold voltage VT, it indicates that the energy storage capacitor CA22 has been charged, so the pwm signal generator 120 can stop outputting the control signal CS2 or output the control signal CS2 with a logic low level to turn off the power switch Q22. Similarly, the pwm signal generator 120 may detect the voltage VS1 of the energy storage capacitor CA21 through the output terminal OT of the energy storage circuit 4641. When the voltage VS1 of the energy storage capacitor CA21 is greater than or equal to the threshold voltage VT, it indicates that the energy storage capacitor CA21 has been charged, so the pwm signal generator 120 can stop outputting the control signal CS1 or output the control signal CS1 with a logic low level to turn off the power switch Q21.
On the other hand, when the external power supply stops providing the input voltage VIN, the auxiliary winding Na will stop supplying power to the pwm signal generator 120 and charging the energy storage element 140, so that the voltage VCC of the energy storage element 140 drops. When the voltage difference between the voltage VS2 of the energy storage capacitor CA22 and the voltage VCC of the energy storage element 140 is greater than the cut-in voltage of the diode D41, the diode D41 is turned on, so that the electric energy stored in the energy storage capacitor CA22 can power the pwm signal generator 120 and charge the energy storage element 140. In addition, when the voltage difference between the voltage VS1 of the energy storage capacitor CA21 and the voltage VS2 of the energy storage capacitor CA22 is greater than the on-state voltage of the diode D422, the pwm signal generator 120 may turn on the power switch Q22, so that the energy storage capacitors CA21 and CA22 jointly supply power to the pwm signal generator 120 and charge the energy storage device 140.
It should be noted that although fig. 3 illustrates the power backup circuit 264 having the diode D41 and the energy storage circuit 2641, and fig. 4 illustrates the power backup circuit 464 having the diode D41 and the two energy storage circuits 4641 and 4642, the invention is not limited to the number of energy storage circuits in the power backup circuit. In other embodiments of the present invention, the power backup circuit may include a diode and N energy storage circuits, where N may be any positive integer. The N energy storage circuits are connected in series in sequence and are connected between the charging circuit and the anode end of the diode of the power backup circuit in series. For the details of the implementation and operation of the N tank circuits, reference may be made to the above description of fig. 3 and fig. 4, and so on, and thus the details are not repeated herein.
In summary, the power conversion apparatus provided in the embodiments of the invention can supply power to the pwm signal generator according to the backup power stored in the power conversion apparatus when the power conversion apparatus is stopped to supply power, so as to prolong the duration of the continuous output voltage of the power conversion apparatus.
Although the present invention has been described with reference to the above embodiments, it should be understood that various changes and modifications can be made therein by those skilled in the art without departing from the spirit and scope of the invention.
Claims (9)
1. A power conversion apparatus, comprising:
a transformer having a primary winding and an auxiliary winding, wherein the primary winding is configured to receive an input voltage from an external power source, and the auxiliary winding is configured to provide an auxiliary voltage;
a first power switch coupled to the primary winding and controlled by a pulse width modulation signal;
the pulse width modulation signal generator is coupled with the first power switch and used for generating the pulse width modulation signal so as to control the on-off of the first power switch;
the energy storage element is coupled with a power supply end of the pulse width modulation signal generator; and
a power circuit coupled to the auxiliary winding, the power terminal of the pwm signal generator, and the energy storage device, for powering the pwm signal generator and charging the energy storage device according to the auxiliary voltage,
wherein the power circuit stores backup power according to the auxiliary voltage when the voltage of the energy storage element is greater than or equal to a threshold voltage, wherein the power circuit powers the PWM signal generator and charges the energy storage element according to the backup power when the external power supply stops providing the input voltage,
the PWM signal generator detects a voltage of the energy storage element through the power terminal, outputs a control signal set to the power circuit when the voltage of the energy storage element is greater than or equal to the threshold voltage, and stores the backup power according to the auxiliary voltage in response to the control signal set.
2. The power conversion device of claim 1, wherein the pwm signal generator is further configured to detect a voltage of the backup power, and when the voltage of the backup power is greater than or equal to the threshold voltage, the pwm signal generator stops outputting the control signal set to the power circuit, and the power circuit completes storing the backup power.
3. The power conversion device of claim 1, wherein the threshold voltage is a minimum voltage required for the pwm signal generator to operate normally.
4. The power conversion device according to claim 1, wherein the power circuit comprises:
a charging circuit, coupled to the auxiliary winding, the power supply terminal of the pwm signal generator, and the energy storage element, for performing rectification filtering on the auxiliary voltage to generate a first voltage, and powering the pwm signal generator and charging the energy storage element according to the first voltage; and
a power backup circuit coupled to the charging circuit, the power terminal of the pwm signal generator and the energy storage device, wherein the power backup circuit stores the backup power according to the first voltage when the voltage of the energy storage device is greater than or equal to the threshold voltage, and wherein the power backup circuit powers the pwm signal generator and charges the energy storage device according to the backup power when the external power source stops providing the input voltage.
5. The power conversion device of claim 4, wherein the first end of the auxiliary winding is coupled to ground, and the charging circuit comprises:
a first diode, an anode terminal of the first diode being coupled to the second terminal of the auxiliary winding to receive the auxiliary voltage, a cathode terminal of the first diode being coupled to a first node and providing the first voltage;
the first end of the auxiliary capacitor is coupled with the grounding end, and the second end of the auxiliary capacitor is coupled with the first node; and
and the anode end of the second diode is coupled with the first node, and the cathode end of the second diode is coupled with the power supply end of the pulse width modulation signal generator and the energy storage element.
6. The power conversion device of claim 4, wherein the power backup circuit comprises:
a first diode, wherein a cathode terminal of the first diode is coupled to the power supply terminal of the pwm signal generator and the energy storage element; and
n energy storage circuits which are connected in series in sequence and are connected between the charging circuit and the anode end of the first diode in series, wherein N is a positive integer,
wherein when the voltage of the energy storage element is greater than or equal to the threshold voltage, the pwm signal generator outputs N control signals to the N energy storage circuits, and the N energy storage circuits respectively store the electric energy according to the first voltage in response to the N control signals to serve as the backup power,
wherein the N energy storage circuits power the PWM signal generator and charge the energy storage element with the backup power through the first diode when the external power supply stops providing the input voltage.
7. The power conversion device according to claim 6, wherein:
the pwm signal generator is further configured to detect a voltage of the electrical energy stored in each of the N tank circuits, and when the voltage of the electrical energy stored in one of the N tank circuits is greater than or equal to the threshold voltage, the pwm signal generator stops outputting a corresponding one of the N control signals to the tank circuit, and the tank circuit completes storing the electrical energy.
8. The power conversion device according to claim 6, wherein:
each of the N tank circuits has an input terminal, a control terminal, and an output terminal, the input terminal of a first one of the N tank circuits is coupled to the charging circuit to receive the first voltage, the output terminal of an mth one of the N tank circuits is coupled to the input terminal of an (M +1) th one of the N tank circuits, the output terminal of an nth one of the N tank circuits is coupled to an anode terminal of the first diode, and the control terminal of each one of the N tank circuits receives one of the N control signals, where M is a positive integer less than N.
9. The power conversion device of claim 8, wherein each of the N energy storage circuits comprises:
a first end and a control end of the second power switch are respectively used as the input end and the control end of the energy storage circuit;
a second diode having an anode terminal coupled to the second terminal of the second power switch; and
and the first end of the energy storage capacitor is coupled with the cathode end of the second diode to be used as the output end of the energy storage circuit, and the second end of the energy storage capacitor is coupled with the ground end.
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| CN100377487C (en) * | 2004-08-12 | 2008-03-26 | 尼克森微电子股份有限公司 | Low power flyback exchanging circuit with primary side voltage feedback |
| JP5104892B2 (en) * | 2010-03-09 | 2012-12-19 | オムロン株式会社 | Switching power supply |
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| JP2001045756A (en) * | 1999-07-27 | 2001-02-16 | Canon Inc | Power-supply apparatus |
| JP2005080343A (en) * | 2003-08-28 | 2005-03-24 | Cosel Co Ltd | Control circuit for switching power supply |
| CN102570822A (en) * | 2010-11-09 | 2012-07-11 | 本田技研工业株式会社 | Power supply device |
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