TW202034616A - Resonant conversion device with extended hold-up time and method of operating the same - Google Patents

Abstract

A resonant conversion device with extended hold-up time includes a resonant conversion unit, a time-extended unit and a control unit. The resonant conversion unit includes a primary side, a transformer unit and a secondary side. The time-extended unit includes a coil and a bridge arm assembly. When a switching frequency of the primary side is less than a critical frequency, the control unit controls the bridge arm assembly to be switched on or off, so that an output voltage of the resonant conversion device is higher than a predetermined voltage during the hold-up time.

Description

Resonance conversion device with extended maintenance time and operation method thereof

The present invention relates to a resonant conversion device with a prolonged maintenance time, in particular to a resonant conversion device that makes the output voltage of the resonant conversion device higher than a predetermined voltage during the maintenance time.

In recent years, electronic products have higher and higher requirements for the quality of power supplies. In particular, precision electronic products may cause irreversible damage when the input voltage is unstable. Therefore, the requirements for power converters that are responsible for power supply also follow the popularization of electronic products. Instead of paying attention to power quality, it gradually improves. When the power converter supplies power to the electronic product, once the input voltage is insufficient, it needs to be able to maintain the power converter to continue to output power for a period of time, so that the back-end coupled electronic product has enough time to react and perform data before power failure Complete storage or backup. Conversely, if the power converter fails to provide a stable output voltage for a period of time after the input voltage is insufficient, it will easily cause the back-end electronic products to not have enough time to respond, resulting in loss of data or damage to the electronic products.

Specifically, when the input voltage of the power converter is insufficient, the bulk capacitance of the power converter will affect the hold-up time of the output voltage of the power converter. In order to effectively extend the time that the power converter can still provide the rated output voltage after the input voltage is insufficient, the most direct way is to increase the capacity of the output capacitor, and use a larger capacitance to provide a longer discharge time. Extend the power supply time of the output voltage after the input voltage is insufficient. However, since the increase of the capacitance of the capacitor will increase the volume of the capacitor, the method of increasing the capacitance of the capacitor to provide a longer discharge time will increase the volume and size of the power converter and make it difficult to miniaturize.

Therefore, how to design a resonant conversion device with extended sustaining time so that the output voltage of the resonant conversion device is higher than the predetermined voltage during the sustaining time to achieve the advantages of miniaturization of the resonant conversion device is what the creator of this project wants to do A major issue to overcome and solve.

In order to solve the above-mentioned problems, the present invention provides a resonant conversion device with extended maintenance time to overcome the problems of the conventional technology. Therefore, the resonance conversion device of the present invention includes: a resonance conversion unit including a primary side, a transformer unit, and a secondary side. The primary side receives the input voltage, the transformer unit is coupled to the primary side and the secondary side, and the secondary side provides output. Voltage. The delay unit includes a coil and a bridge arm group, the coil is coupled to the transformer unit, and the bridge arm group is coupled to the coil and the secondary side. The control unit controls the resonance conversion unit to convert the input voltage to the output voltage. Wherein, when the switching frequency of the primary side is less than the critical frequency, the control unit controls the bridge arm group to switch on or off, so that the output voltage is higher than the predetermined voltage within the maintenance time.

In order to solve the above-mentioned problems, the present invention provides an operating method of a resonant conversion device with extended maintenance time to overcome the problems of the prior art. Therefore, the operating method of the resonance conversion device of the present invention includes the following steps: (a) A resonance conversion unit is provided to convert an input voltage into an output voltage. (b) Provide a delay unit. When a switching frequency of the resonance conversion unit is greater than or equal to a critical frequency, the delay unit does not work. (c) Provide a control unit to control the resonance conversion unit and the delay unit. And (d) when a switching frequency of the resonance conversion unit is less than the critical frequency, the control unit controls the delay unit to switch on or off so that the output voltage is higher than a predetermined voltage for a maintenance time.

In order to further understand the technology, means and effects of the present invention to achieve the intended purpose, please refer to the following detailed description and drawings of the present invention. I believe that the purpose, features and characteristics of the present invention can be obtained from this in depth and For specific understanding, however, the accompanying drawings are only provided for reference and illustration, and are not intended to limit the present invention.

The technical content and detailed description of the present invention are described as follows with the drawings:

Please refer to FIG. 1 for a block diagram of a resonant conversion device with extended sustain time according to the present invention. The resonance conversion device 1 receives the input voltage Vin, and converts the input voltage Vin into the output voltage Vo to supply power to the load 2. The resonance conversion device 1 includes a resonance conversion unit 10, a delay unit 20 and a control unit 30. The resonance conversion unit 10 is coupled to the delay unit 20, and the control unit 30 is coupled to the resonance conversion unit 10 and the delay unit 20. The resonant conversion unit 10 includes a primary side 102, a transformer unit 104, and a secondary side 106. The primary side 102 receives an input voltage Vin, the transformer unit 104 is coupled to the primary side 102 and the secondary side 106, and the secondary side 106 provides an output voltage Vo . The delay unit 20 includes a coil 202 and a bridge arm group 204, the coil 202 is coupled to the transformer unit 104, and the bridge arm group 204 is coupled to the coil 202 and the secondary side 106. The control unit 30 outputs a control signal Sc to control the primary side 102, the secondary side 106, and the bridge arm group 204, so as to maintain the operation of the resonance conversion device 1.

When the input voltage Vin is normal, the control unit 30 outputs a control signal Sc to control the primary side 102 and the secondary side 106 to control the resonance conversion unit 10 to convert the input voltage Vin into an output voltage Vo. At this time, the control unit 30 does not output the control signal Sc to control the bridge arm group 204, so that the delay unit 20 does not work. When the input voltage Vin is insufficient, the control unit 30 outputs a control signal Sc to further control the bridge arm group 204 to convert the energy stored in the primary side 102 into the output voltage Vo, and temporarily maintain the output voltage Vo higher than the predetermined output voltage (afterwards Referred to as the predetermined voltage).

It is worth mentioning that in one embodiment of the present invention, the insufficient input voltage Vin mainly refers to the gradual decrease of the input voltage Vin to zero. Specifically, the front end of the resonant conversion device 1 is usually coupled to a front-end device (for example, but not limited to a power factor corrector). Therefore, when the front-end device stops operating due to an input power failure or the front-end device itself is abnormal, the front-end device The output voltage of the first-stage device will temporarily remain above a certain level due to the energy stored in the output capacitor. When the energy is gradually consumed, the output voltage of the previous-stage device (that is, the input voltage Vin of the resonant converter device 1) gradually drops to 0 .

Specifically, the main purpose of the present invention is that when the input voltage Vin of the resonance conversion device 1 is insufficient, the control unit 30 can control the conduction or non-conduction of the bridge arm group 204, so that the coil 202 is short-circuited or coupled to the secondary side 106. In order to transmit the energy of the primary side 102 to the secondary side 106 through the transformation unit 104 or the delay unit 20, the resonant converter device 1 can still maintain the output voltage Vo higher than the sustaining time when the input voltage Vin is insufficient. The predetermined voltage. For example, but not limited to, the resonant converter device without the delay unit 20 can only maintain the output voltage Vo not lower than the predetermined voltage for about 10 milliseconds, while the resonant converter device 1 of the present invention includes the delay unit 20, so it can be extended The maintenance time is, for example, but not limited to, 20 milliseconds or more, which means that the maintenance time when the output voltage Vo is higher than the predetermined voltage will be prolonged to about twice or more. Compared with the resonant converter without the delay unit 20, the resonant converter 1 of the present invention does not need to increase the energy storage capacity of the secondary side 106 to achieve the effect of extending the maintenance time.

Please refer to FIG. 2A for a schematic circuit diagram of the first embodiment of the resonant conversion device with extended sustaining time according to the present invention. Please refer to FIG. 1 for complex cooperation. The primary side 102 includes a switching unit 102-1 and a resonance unit 102-2. The switching unit 102-1 receives an input voltage Vin, and the resonance unit 102-2 is coupled to the primary side of the switching unit 102-1 and the transformation unit 104. The secondary side 106 includes a rectifier unit 106-1 and an output capacitor 106-2. The rectifier unit 106-1 is coupled to the secondary side of the transformer unit 104, and the output capacitor 106-2 is coupled to the rectifier unit 106-1 and the bridge arm group 204 , And the output capacitor 106-2 stabilizes the voltage value of the output voltage Vo. The bridge arm group 204 includes a first bridge arm 204-1, a second bridge arm 204-2, and an energy storage capacitor 204-3 connected in parallel. The first bridge arm 204-1 includes a first diode D1 and a first switch connected in series. S1, the second bridge arm 204-2 includes a second diode D2 and a second switch S2 connected in series. The coil 202 includes a first end and a second end, the first end is coupled between the anode of the first diode D1 and the first switch S1, and the second end is coupled between the anode of the second diode D2 and the second switch S2 between. The cathode of the first diode D1, the cathode of the second diode D2, and one end of the energy storage capacitor 204-3 are coupled to the output capacitor 106-2.

The switching frequency of the switching unit 102-1 and the rectifying unit 106-1 can be determined by the control unit 30 according to the state of the input terminal or the output terminal of the resonant conversion device 1 detected by it. Specifically, when the control signal Sc sent by the control unit 30 to the switching unit 102-1, the switching frequency of which is greater than or equal to the critical frequency (the critical frequency value is set by the circuit designer according to practice), represents the input voltage Vin of the resonance conversion device 1 normal. At this time, the control unit 30 controls the switching of the switching unit 102-1 to store the energy of the input voltage Vin to the resonance unit 102-2. The energy on the resonance unit 102-2 is converted to the secondary side 106 by the transformer unit 104, and rectified into the output voltage Vo by the rectifier unit 106-1, and the voltage value of the output voltage Vo is stabilized by the output capacitor 106-2. At this time, the control unit 30 does not output the control signal Sc to control the first switch S1 and the second switch S2 of the bridge arm group 204, so that the first switch S1 and the second switch S2 are not conductive. Since the first switch S1 and the second switch S2 are not conductive, the coil 202 cannot form an energy storage path, and the delay unit 20 does not work.

When the switching frequency of the switching unit 102-1 is less than the critical frequency, it means that the input voltage Vin of the resonance conversion device 1 is insufficient. That is, when the input voltage Vin is lower, the switching frequency of the switching unit 102-1 will be lower and lower. When the switching frequency of the switching unit 102-1 is already lower than the critical frequency of the control unit 30, it means that the input voltage Vin has fallen below the acceptable range of the control unit 30. At this time, in order to maintain the output voltage Vo higher than the predetermined voltage within the maintenance time, the control unit 30 controls the first switch S1 and the second switch S2 of the bridge arm group 204 to switch on or off. When the control unit 30 controls the first switch S1 and the second switch S2 of the bridge arm group 204 to switch on, the coil 202 is short-circuited, so that the resonance unit 102-2 starts to store energy. At this time, the resonance conversion device 1 only relies on the energy previously stored in the output capacitor 106-2 to stabilize the voltage value of the output voltage Vo. When the control unit 30 controls the first switch S1 and the second switch S2 of the bridge arm group 204 to not conduct, the energy stored in the resonance unit 102-2 is provided to the output capacitor 106- of the secondary side 106 through the coil 202 and the bridge arm group 204 2. The output capacitor 106-2 can continuously maintain the output voltage Vo higher than the predetermined voltage.

It is worth mentioning that because the operation mode of the present invention is based on the control signal Sc output by the control unit 30 as the basis for judgment, that is, the control signal Sc for controlling the switching unit 102-1 is provided by the control unit 30, and the control The unit 30 itself can know the switching frequency when it outputs the control signal Sc. In this way, the situation of insufficient input voltage Vin can be obtained more quickly and accurately. In addition, when the load of the resonance conversion device 1 turns to a heavy load, the switching frequency of the switching unit 102-1 may also be lower than the critical frequency. Therefore, in order to increase the accuracy of identifying whether the input voltage Vin is really insufficient, in an embodiment of the present invention, a condition to assist in determining whether the input voltage Vin is insufficient may also be added. For example, but not limited to, in one embodiment of the present invention, the power supply normal signal (AC_OK signal) provided when the electronic device (such as the power factor correction device, not shown) coupled to the front end of the resonance conversion device 1 is normal . When the input voltage Vin is insufficient, the control unit 30 consciously switches the frequency less than the critical frequency, and the control unit 30 does not receive the AC_OK signal provided by the front-end device. At this time, it can be accurately determined that the reason for the reduction of the switching frequency is due to the input voltage. Insufficient Vin can reduce the occurrence of malfunctions.

Furthermore, when the switching frequency of the switching unit 102-1 of the primary side 102 is greater than or equal to the critical frequency, the control unit 30 controls or adjusts the switching frequency of the switching unit 102-1 according to the voltage value of the output voltage Vo. When the switching frequency of the switching unit 102-1 is less than the critical frequency (for example, but not limited to, 40 kHz) and the AC_OK signal from the front-end device is not received (assuming the AC_OK judgment condition is introduced), it means that the input voltage Vin is insufficient. The control unit 30 will forcibly increase the switching frequency of the switching unit 102-1 to the resonance frequency (for example, but not limited to, 50kHz), and when the switching frequency of the switching unit 102-1 is increased to the resonance frequency, the control unit 30 controls the switching The switching frequency and duty cycle of the unit 102-1 are fixed values (that is, the switching frequency is fixed at the resonance frequency). When the switching frequency of the switching unit 102-1 is adjusted to the resonance frequency, the resonance current of the resonance unit 102-2 will be reduced, so as to reduce the loss of the resonance conversion device 1 in order to maintain the output voltage Vo stable. When the switching frequency of the switching unit 102-1 of the primary side 102 is less than the critical frequency, the control unit 30 controls the bridge arm group 204 to start switching, and adjusts the switching frequency of the bridge arm group 204 to the resonance frequency, and then the control unit 30 will output The voltage Vo is used to adjust the duty cycle of the bridge arm group 204. The duty cycle determines the amount of energy stored in the resonant unit 102-2. When the input voltage Vin is high, the required duty ratio is small to meet the load requirements. The energy needed, and vice versa. When the duty cycle of the bridge arm group 204 is larger (that is, the duty cycle of the first switch S1 and the second switch S2 is larger), the more energy can be obtained on the secondary side 106, so that the output The maintenance time for the voltage Vo to be higher than the predetermined voltage can be longer (for example, but not limited to, the duration is extended from 2 times to 2.5 times).

Please refer to FIG. 2B for a schematic circuit diagram of the second embodiment of the resonant conversion device with extended sustaining time according to the present invention. Please refer to FIG. 2A for further cooperation. The difference between the resonance conversion device 1 of FIG. 2B and the resonance conversion device 1 of FIG. 2A is that the resonance unit 102-2' of FIG. 2B is a double-capacitance resonance unit, while the resonance unit 102-2 of FIG. 2A is a single-capacitance resonance unit. unit. The difference is that the single-capacitor resonant unit 102-2 has only one resonant capacitor C coupled to the upper switch Q1, the lower switch Q2 and the first resonant inductor L1 of the switching unit 102-1, while the double-capacitor resonant unit 102 -2' is mainly a circuit structure in which two resonant capacitors (C1, C2) are connected in series, which are coupled to the upper switch Q1, the lower switch Q2 and the second resonant inductor L2 of the switching unit 102-1, so compared to a single resonant capacitor C In other words, using two resonant capacitors (C1, C2) can reduce the voltage stress on each resonant capacitor (C1, C2), and make the choice of resonant capacitor specifications more flexible (that is, resonant capacitors can be reduced in specifications). However, no matter it is the resonant conversion device of FIG. 2B or FIG. 2A, the control method for extending the time is the same.

It is worth mentioning that in an embodiment of the present invention, the switching unit 102-1 may be a half-bridge type (as shown in FIGS. 2A and 2B) or a full-bridge type (not shown). The full-bridge switching unit is a structure in which two sets of bridge arms are connected in parallel, and its circuit structure or control method is known to those skilled in the art, and will not be repeated. In addition, in an embodiment of the present invention, the switching elements (such as the upper switch Q1, the lower switch Q2, the first rectifier switch Sb1, the second rectifier switch Sb2, the first switch S1, and the second switch S2) are connected in parallel next to The diode may be a junction diode inside the switching element, or may be an external diode additionally connected in parallel.

Please refer to FIG. 3A for a schematic diagram of the first current loop of the resonant conversion device with extended sustaining time whose switching frequency is lower than the critical frequency. When the switching frequency of the switching unit 102-1 of the primary side 102 is less than the critical frequency, the control unit 30 outputs a control signal Sc to control the conduction or non-conduction of the first switch S1 and the second switch S2 of the bridge arm group 204. When the upper switch Q1 of the switching unit 102-1 is turned on and the switching frequency is less than the critical frequency, the control unit 30 controls the first switch S1 and the second switch S2 to be turned on, and the path from the rectifying unit 106-1 to the output capacitor 106-2 is not Conduction. At this time, the input voltage Vin of the primary side 102, the switching unit 102-1 (upper switch Q1), and the resonance unit 102-2 form a current loop. Since the first switch S1 and the second switch S2 are turned on, the coil 202 is short-circuited. At this time, the coil 202 of the delay unit 20 (flowing from the dotted end), the first switch S1 and the second switch S2 form a first current loop I1, so that the components flowing through the resonance unit 102-2 begin to store energy (that is, resonance The capacitor C and the first resonant inductor L1 can continue to store energy). Moreover, since the rectifier unit 106-1 on the secondary side 106 is not turned on, the energy stored on the output capacitor 106-2 supplies power to the load 2 and is continuously consumed.

Please refer to FIG. 3B for a schematic diagram of the second current loop of the resonant conversion device with extended sustaining time whose switching frequency is lower than the critical frequency. For the combination, refer to FIG. 2A. When the upper switch Q1 of the switching unit 102-1 is turned on and the switching frequency is less than the critical frequency, the control unit 30 controls the first switch S1 and the second switch S2 to be non-conductive, and the coil 202 of the delay unit 20 (outflow from the dotted end), the first A diode D1, an energy storage capacitor 204-3, an output capacitor 106-2, and a second switch S2 (the junction diode flowing through the second switch S2: Junction Diode) form a second current loop I2 to make the resonant unit The energy on 102-2 is coupled to the coil 202, and the energy storage capacitor 204-3 and the output capacitor 106-2 are discharged, and when the energy stored on the output capacitor 106-2 is insufficient, the energy can be used by the energy storage capacitor 204-3 It is provided to the output capacitor 106-2, so that the output capacitor 106-2 can continuously stabilize the output voltage Vo. Furthermore, when the switching frequency is less than the critical frequency and the first switch S1 and the second switch S2 are not conducting, the secondary side 106 also provides a path for part of the energy on the resonance unit 102-2 to pass. When the first rectifier switch Sb1 is not conducting, the current flows through the junction diode of the first rectifier switch Sb1, and when the first rectifier switch Sb1 is conducting, the current flows through the first rectifier switch Sb1. The conduction or non-conduction of the first rectifier switch Sb1 can be controlled by the control unit 30, but for efficiency considerations, when the first rectifier switch Sb1 is turned on, the efficiency is better.

It is worth mentioning that in an embodiment of the present invention, FIGS. 3A and 3B illustrate the current path when the upper switch Q1 of the switching unit 102-1 is turned on. When the lower switch Q2 of the switching unit 102-1 is turned on, the primary The current path of the side 102 is that the lower switch Q2 of the switching unit 102-1 and the resonant unit 102-2 form another current loop (the current path of the primary side 102 is opposite to that of FIGS. 3A and 3B), and the secondary side 106 and the delay unit 20 The current loop is the same as in FIGS. 3A and 3B, but when the first switch S1 and the second switch S2 are not conducting, the current path through which part of the energy provided by the secondary side 106 to the resonant unit 102-2 passes is changed to the second rectifier switch Sb2 after.

Furthermore, when the first switch S1 and the second switch S2 are not conducting, since current can flow through the junction diode of the second switch S2, a second current loop I2 is formed, so that between the first switch S1 and When the second switch S2 is not conducting, there is a path for current to flow. Therefore, the usable energy will not have a path to circulate due to the non-conduction of the first switch S1 and the second switch S2, so the waste of usable energy can be reduced. In addition, when the first switch S1 and the second switch S2 are not conducting, the energy storage capacitor 204-3 can store energy and supplement the shortage of the output capacitor 106-2. Therefore, in addition to stabilizing the voltage value of the output voltage Vo, it can also achieve an effective and stable ripple of the output voltage Vo when the input voltage is insufficient, and at the moment when the first switch S1 and the second switch S2 are not conducting, It prevents the excess current from surging to the output capacitor 106-2 and causing a current spike.

Please refer to FIG. 4 for a schematic diagram of the waveform of the resonant conversion device with extended sustaining time of the present invention when the switching frequency is less than the critical frequency. Please refer to FIGS. 1 to 3B for the combination, and refer to FIGS. 3A and 3B repeatedly. When the switching frequency is less than the critical frequency, and at time t0-t3, the upper switch Q1 of the primary side 102 is turned on, and at time t0-t1, the path from the rectifying unit 106-1 to the output capacitor 106-2 is not turned on, and The first switch S1 and the second switch S2 are turned on to cause a short circuit of the coil 202 (the first current loop I1). At this time, the resonant capacitor C and the first resonant inductor L1 in the resonant unit 102-2 store energy, and the first resonant current Ir1 starts to rise. When the time is between t1-t2, the first switch S1 and the second switch S2 are not conductive. At this time, the first resonant inductor L1 gradually changes from energy storage to energy release, the first resonant current Ir1 gradually changes from rising to falling, and energy flows through the junction diode of the second switch S2 (the second current loop I2). At this time, if the first rectifier switch Sb1 is turned on (when it is not conductive, the path from the rectifier unit 106-1 to the output capacitor 106-2 is turned on, so that part of the current flows through the first rectifier switch Sb1 pair). The output capacitor 106-2 is charged. When the time is between t2-t3, the path from the rectifying unit 106-1 to the output capacitor 106-2 is not conductive, and the first switch S1 and the second switch S2 are not conductive either. At this time, no energy from the primary side 102 is released to the secondary side 106 and the delay unit 20, so that the primary side 102 forms a current path by itself.

When the switching frequency is less than the critical frequency, and at time t4-t7, the lower switch Q2 of the primary side 102 is turned on, and at time t4-t5, t5-t6, t6-t7, the first resonant current Ir1 and the first resonance The current Ir2 is exactly the opposite of the time t0-t3. Originally, when the switch Q1 is turned on, the current flowing through the first rectifier switch Sb1 becomes the second rectifier switch Sb2, and the current waveforms flowing through the first switch S1 and the second switch S2 are exactly opposite to the time t0-t3.

Please refer to FIG. 5 for a flow chart of the operation method with extended maintenance time of the present invention, and refer to FIGS. 1 to 4 for compound cooperation. The resonance conversion device 1 receives the input voltage Vin, and converts the input voltage Vin into the output voltage Vo to supply power to the load 2. The resonance conversion device 1 includes a resonance conversion unit 10, a delay unit 20 and a control unit 30. The resonance conversion unit 10 is coupled to the delay unit 20, and the control unit 30 is coupled to the resonance conversion unit 10 and the delay unit 20. The operation method includes the following steps: converting an input voltage into an output voltage (S200). When the input voltage Vin is normal, the control unit 30 outputs a control signal Sc to control the primary side 102 and the secondary side 106 to control the resonance conversion unit 10 to convert the input voltage Vin into an output voltage Vo. Then, when the switching frequency of the resonance conversion unit is greater than or equal to the critical frequency, the delay unit does not work (S400). When the switching frequency of the resonance conversion unit 10 is greater than or equal to the critical frequency, it means that the input voltage Vin is still in the normal range. At this time, the control unit 30 does not output the control signal Sc to control the bridge arm group 204, so that the delay unit 20 does not work.

When the switching frequency of the resonance conversion unit is less than the critical frequency and the control unit controls the bridge arm group to be turned on, the primary side stores energy (S600). When the switching frequency of the resonant conversion unit 10 is less than the critical frequency (it is judged that the AC_OK signal provided by the front-end device can be added at the same time, it has been explained in the previous paragraph and will not be repeated here), it means that the input voltage Vin is insufficient. When the control unit 30 outputs the control signal Sc to turn on the switches in the bridge arm group 204, the coils are short-circuited, so that the resonance unit 102-2 in the primary side stores energy. When the switching frequency is less than the critical frequency and the control unit controls the bridge arm group to not conduct, the energy on the primary side is provided to the secondary side through the coil and the bridge arm group (S800). Through steps (S600) to (S800), the output voltage Vo of the resonance conversion device 1 can be made higher than the predetermined voltage within the maintenance time.

In summary, the main purpose of the present invention is that when the input voltage of the resonance conversion device is insufficient, the control unit can control the delay unit to transmit the induced energy to the resonance conversion unit through the electromagnetic coupling of the coil to the transformation unit, so that the resonance The conversion device can still achieve the effect of maintaining the output voltage higher than the predetermined voltage during the maintenance time when the input voltage is insufficient.

However, the above are only detailed descriptions and drawings of the preferred embodiments of the present invention. However, the features of the present invention are not limited to these, and are not intended to limit the present invention. The full scope of the present invention should be referred to the following application The scope of the patent shall prevail. All embodiments that conform to the spirit of the scope of the patent application of the present invention and similar variations should be included in the scope of the present invention. Anyone familiar with the art in the field of the present invention can easily think of it. Changes or modifications can be covered in the following patent scope of this case.

1: Resonance conversion device

10: Resonant conversion unit

102: Primary side

102-1: Switching unit

Q1: Up switch

Q2: Down switch

102-2, 102-2’: Resonant unit

C, C1, C2: resonant capacitor

L1: first resonant inductor

L2: second resonant inductor

104: Transformer unit

106: secondary side

Sb1: The first rectifier switch

Sb2: The second rectifier switch

106-1: Rectifier unit

106-2: Output capacitor

20: Delay unit

202: Coil

204: Bridge Arm Group

204-1: First bridge arm

D1: The first diode

S1: First switch

204-2: second bridge arm

D2: The second diode

S2: second switch

204-3: Energy storage capacitor

30: control unit

2: load

Vin: input voltage

Vo: output voltage

Sc: control signal

I1: The first current loop

I2: second current loop

Ir1: first resonant current

Ir2: first resonant current

t0-t7: time

(S200)~(S800): steps

Fig. 1 is a block diagram of a resonant conversion device with extended sustaining time according to the present invention;

2A is a schematic circuit diagram of the first embodiment of the resonant conversion device with extended sustain time according to the present invention;

2B is a schematic circuit diagram of the second embodiment of the resonant conversion device with extended sustain time according to the present invention;

3A is a schematic diagram of the first current loop of the resonant converter with extended sustaining time whose switching frequency is lower than the critical frequency;

3B is a schematic diagram of the second current loop of the resonant converter with extended sustaining time whose switching frequency is lower than the critical frequency;

FIG. 4 is a schematic diagram of the waveform of the resonant conversion device with extended holding time when the switching frequency is less than the critical frequency; and

Fig. 5 is a flowchart of an operation method with extended maintenance time of the present invention.

1: Resonance conversion device

10: Resonant conversion unit

102: Primary side

104: Transformer unit

106: secondary side

20: Delay unit

202: Coil

204: Bridge Arm Group

30: control unit

2: load

Vin: input voltage

Vo: output voltage

Sc: control signal

Claims (16)

A resonant conversion device with extended maintenance time, including: A resonance conversion unit includes a primary side, a transformer unit, and a secondary side. The primary side receives an input voltage, the transformer unit is coupled to the primary side and the secondary side, and the secondary side outputs an output Voltage; A delay unit including a coil and a bridge arm group, the coil is coupled to the transformer unit, and the bridge arm group is coupled to the coil and the secondary side; and A control unit that controls the resonance conversion unit to convert the input voltage into the output voltage; Wherein, when a switching frequency of the primary side is less than a critical frequency, the control unit controls the bridge arm group to switch on or off, so that the output voltage is higher than a predetermined voltage for a maintenance time. According to the resonant conversion device described in item 1 of the scope of patent application, the primary side includes: A switching unit that receives the input voltage; and A resonance unit coupled to the switching unit and the transformation unit; Wherein, when the switching frequency is less than the critical frequency, the control unit controls the switching unit to switch on or off to provide energy for storing energy on the resonance unit; the energy is coupled to the delay through the coil and the transformer unit Unit, so that the delay unit can maintain the output voltage. For the resonance conversion device described in item 2 of the scope of patent application, when the switching frequency is less than the critical frequency, the control unit controls the switching frequency to gradually increase to a resonance frequency of the resonance unit; when the switching frequency is increased When the resonance frequency is reached, the control unit controls the switching frequency to be fixed at the resonance frequency, and controls the switching unit to fix a duty cycle. In the resonant conversion device described in item 2 of the scope of patent application, the switching unit is a half-bridge switching unit or a full-bridge switching unit. The resonant conversion device described in claim 1, wherein when the switching frequency is less than the critical frequency, and the control unit does not receive an input confirmation signal provided by a front-end device coupled to the front end of the resonant conversion device At this time, the control unit starts to control the bridge arm group to switch on or off. According to the resonant conversion device described in item 1 of the scope of patent application, the bridge arm group includes: A first bridge arm, coupled to the secondary side, and including a first diode and a first switch connected in series, the coil is coupled to the first diode and the first switch; and A second bridge arm, connected in parallel with the first bridge arm, and comprising a second diode and a second switch connected in series, the coil is coupled to the second diode and the second switch; Wherein, when the switching frequency is less than the critical frequency, and the first switch and the second switch are turned on, the coil, the first switch and the second switch form a first current loop. According to the resonant conversion device described in item 6 of the scope of patent application, when the switching frequency is greater than or equal to the critical frequency, the first switch and the second switch are not turned on, so that the delay unit does not work. According to the resonant conversion device described in item 6 of the scope of patent application, the bridge arm group further includes: An energy storage capacitor connected in parallel with the second bridge arm; Wherein, when the switching frequency is less than the critical frequency, and the first switch and the second switch are not conducting, the coil, the first diode, the second switch and the energy storage capacitor form a second current loop . The resonant conversion device described in item 6 of the scope of patent application, wherein the secondary side includes: A rectifier unit, coupled to the transformer unit; and An output capacitor, coupled to the rectifier unit and the bridge arm group; Wherein, when the switching frequency is less than the critical frequency, and the first switch and the second switch are not conducting, the output capacitor stabilizes the output voltage. For the resonance conversion device described in item 9 of the scope of patent application, when the switching frequency is greater than or equal to the critical frequency, the energy of the transformation unit is rectified into the output voltage by the rectification unit, and the output capacitor stabilizes the output voltage The voltage value. An operating method of a resonant conversion device with extended holding time. The operating method includes the following steps: (a) Provide a resonance conversion unit to convert an input voltage to an output voltage; (b) Provide a delay unit, when a switching frequency of the resonance conversion unit is greater than or equal to a critical frequency, the delay unit does not work; (c) Provide a control unit to control the resonance conversion unit and the delay unit; and (d) When a switching frequency of the resonance conversion unit is less than the critical frequency, the control unit controls the delay unit to switch on or off so that the output voltage is higher than a predetermined voltage for a maintenance time. As the operation method described in item 11 of the scope of patent application, step (d) includes: (d1) The control unit controls the switching frequency to gradually increase to a resonance frequency of the resonance unit; when the switching frequency is adjusted to the resonance frequency, the control unit controls the switching frequency to be fixed at the resonance frequency, and controls the A switching unit of the resonant conversion unit fixes a duty cycle. As the operation method described in item 11 of the scope of patent application, step (d) includes: (d2) When the switching frequency is less than the critical frequency and the control unit does not receive an input confirmation signal provided by a front-end device coupled to the front end of the resonance conversion device, the control unit controls the delay unit to switch on or No conduction. As the operation method described in item 11 of the scope of patent application, step (d) includes: (d3) The delay unit includes a coil and a first switch, a second switch, and an energy storage capacitor connected in parallel. The coil is coupled to the first switch and the second switch; when the first switch and the second switch are When the switch is turned on, the coil, the first switch and the second switch form a first current loop. The operation method described in item 14 of the scope of patent application, wherein step (d3) further includes: (d4) The delay unit further includes an energy storage capacitor; when the first switch and the second switch are not conductive, the coil, the first diode, the second switch and the energy storage capacitor form a second Current loop. The operation method described in item 14 of the scope of patent application, wherein step (d3) includes: (d5) When the first switch and the second switch are not conducting, the delay unit provides energy to the resonance conversion unit, so that the resonance conversion unit stabilizes the output voltage.

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