CN210297332U - Control circuit with prolonged holding time and conversion system thereof - Google Patents

Abstract

The utility model provides a control circuit and switching system with extension hold time, the control circuit is coupled switching circuit's bus route, and this control circuit includes: bypass circuit, energy storage capacitor and auxiliary power supply circuit. The auxiliary power supply circuit provides an energy storage voltage to the energy storage capacitor according to the working voltage provided by the conversion circuit; when the bus voltage of the bus path is less than or equal to the energy storage voltage, the energy storage voltage is provided to the bus path through the bypass circuit, so that the bus voltage is greater than or equal to the predetermined voltage within the holding time. Therefore, the control circuit with the function of prolonging the holding time and the conversion system with the function of prolonging the holding time are provided, the control circuit is used for controlling the energy storage capacitor to prolong the holding time, and a special structural design can be used for reducing the withstand voltage of the energy storage capacitor, so that the volume of the energy storage capacitor is reduced, and the cost is saved.

Description

Control circuit with prolonged holding time and conversion system thereof

Technical Field

The present invention relates to a control circuit with an extended holding time, and more particularly, to a control circuit with an extended holding time and a switching system thereof, which can maintain a voltage greater than or equal to a predetermined voltage during the holding time.

Background

In recent years, as electronic products are becoming more popular and the power quality of the operation of the electronic products is stably supplied, the power supply requirement of the power supply device is gradually increased along with the popularization of the electronic products and the importance of the power quality. The safety specification of the power supply device provides that, in the process of supplying power to the electronic product, if the power supply device is powered off, the power supply device still has to maintain the power supply device to output power for a short time.

In order to meet the requirements of safety regulations, it is a common practice to increase the capacity of the energy storage capacitor at the output terminal of the power supply device. When the capacity of the energy storage capacitor is larger, the maintaining time can be maintained for a longer time, and the requirement of the safety specification can be met. However, this method will increase the volume of the energy storage capacitor due to the required capacity of the energy storage capacitor. In addition, since the energy storage capacitor is directly coupled to the power line terminal and the ground terminal of the output terminal of the power supply device, the withstand voltage of the energy storage capacitor must be larger than the output voltage (for example, but not limited to 400V) of the output terminal of the power supply device to avoid the damage caused by insufficient withstand voltage of the energy storage capacitor. However, increasing the withstand voltage of the storage capacitor also means that the volume of the storage capacitor increases.

Therefore, how to design a control circuit with extension hold time and have the conversion system of extension hold time, except utilizing control circuit to reach control energy storage electric capacity and prolong the hold time, more usable special structural design reduces energy storage electric capacity's withstand voltage, and then reduces energy storage electric capacity's volume and save cost, is the utility model discloses the technical problem that the people need solve.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to solve above-mentioned problem, provide a control circuit and switching system with extension hold time.

To achieve the above object, the present invention provides a control circuit with extended holding time coupled to a bus path of a switching circuit, the control circuit comprising: and the bypass circuit is coupled with the fire wire end of the bus path. The energy storage capacitor comprises a first end and a second end, wherein the first end is coupled with the bypass circuit, and the second end is coupled with the ground wire end of the bus path. And an auxiliary power circuit coupled to the bypass circuit and the conversion circuit. The auxiliary power supply circuit provides an energy storage voltage to the energy storage capacitor according to the working voltage provided by the conversion circuit; when the bus voltage of the bus path is less than or equal to the energy storage voltage, the energy storage voltage is provided to the bus path through the bypass circuit, so that the bus voltage is greater than or equal to the predetermined voltage within the holding time.

In one embodiment, the auxiliary power circuit includes: the conversion unit is coupled with the conversion circuit. And the voltage stabilizing circuit is coupled with the conversion unit. And the charging path is coupled with the voltage stabilizing circuit, the energy storage capacitor and the bypass circuit. The voltage stabilizing circuit generates a stabilized voltage according to the auxiliary voltage; the voltage-stabilizing voltage conducts the charging path, and the voltage-stabilizing voltage charges the energy-storing capacitor through the charging path, so that the energy-storing capacitor establishes the energy-storing voltage; when the bus voltage is less than or equal to the energy storage voltage, the energy storage voltage is provided to the bus path through the bypass circuit.

In an embodiment, the converting unit is an induction coil, the induction coil is coupled to a transformer of the converting circuit, and the working voltage of the transformer is converted into the auxiliary voltage by electromagnetic coupling.

In an embodiment, the converting unit is a switching power converter, and the switching power converter is coupled to the bus path and converts the bus voltage into an auxiliary voltage by using the bus voltage as a working voltage.

In an embodiment, the converting unit is a linear power converter, and the linear power converter is coupled to the bus path and uses the bus voltage as the working voltage to convert the working voltage into the auxiliary voltage.

In one embodiment, the conversion circuit comprises an ac-to-dc converter; the conversion unit is coupled to the ac-dc converter and obtains a working voltage according to an operation of the ac-dc converter to convert the working voltage into an auxiliary voltage.

In one embodiment, the conversion circuit comprises a dc-dc converter; the conversion unit is coupled to the DC-DC converter and obtains a working voltage according to the operation of the DC-DC converter so as to convert the working voltage into an auxiliary voltage.

In one embodiment, the bypass circuit is a first diode; when the bus voltage is less than or equal to the energy storage voltage, the first diode is forward biased, and when the bus voltage is greater than the energy storage voltage, the first diode is reverse biased.

In one embodiment, the bypass circuit includes: the voltage detection circuit is coupled to the bus path. The control unit is coupled to the voltage detection circuit. The switch unit is coupled with the bus path, the energy storage capacitor and the control unit. The voltage detection circuit detects a voltage signal of the bus voltage, and the control unit judges whether to conduct the switch unit according to the voltage signal; when the switch unit is turned on, the energy storage voltage supplements the bus voltage through the switch unit.

In one embodiment, the auxiliary power circuit further includes: the current limiting resistor is coupled with the voltage stabilizing circuit and the charging path. The current limiting resistor limits the charging current for charging the energy storage capacitor.

In one embodiment, the auxiliary power circuit further includes: the transistor is coupled with the voltage stabilizing circuit. And the thyristor unit is coupled with the voltage stabilizing circuit and the transistor. And a current detection resistor coupled to the transistor and the thyristor. The thyristor unit controls the transistor to provide a charging current with a fixed current value according to the voltage drop of the current detection resistor so as to charge the energy storage capacitor.

In an embodiment, the current adjusting unit formed by the transistor, the thyristor and the current detecting resistor is the charging path.

In one embodiment, the charging path is a diode component.

In one embodiment, the energy storage voltage is a regulated voltage minus a switch-on voltage of the charging path.

In one embodiment, the auxiliary power circuit further includes: and the voltage stabilizing unit is coupled with the voltage stabilizing circuit, the charging path and the energy storage capacitor. The voltage stabilizing unit limits the gate voltage of the charging path to be less than or equal to the rated voltage.

In one embodiment, the withstand voltage of the storage capacitor is less than the maximum voltage of the bus voltage.

In one embodiment, the auxiliary power circuit further includes: the second diode is coupled with the voltage stabilizing circuit and the charging path. When the bus voltage is less than the regulated voltage, the second diode is forward biased, so that the regulated voltage is released to the bus path.

To achieve the above objects, the present invention further provides a conversion system to overcome the problems of the prior art. Therefore, the utility model discloses a conversion system includes: a conversion circuit, comprising: and the first stage conversion unit converts the input power supply into the bus voltage. And the second-stage conversion unit is coupled with the first-stage conversion unit through a bus path and converts the bus voltage into an output power supply. And a control circuit coupled to the bus path and including: and the bypass circuit is coupled with the fire wire end of the bus path. The energy storage capacitor comprises a first end and a second end, wherein the first end is coupled with the bypass circuit, and the second end is coupled with the ground wire end of the bus path. And an auxiliary power circuit coupled to the bypass circuit and the conversion circuit. The auxiliary power supply circuit provides an energy storage voltage to the energy storage capacitor according to the working voltage provided by the conversion circuit; when the bus voltage of the bus path is less than or equal to the energy storage voltage, the energy storage voltage is provided to the bus path through the bypass circuit, so that the bus voltage is greater than or equal to the predetermined voltage within the holding time.

Drawings

FIG. 1 is a block diagram of a switching system with extended hold time according to the present invention;

fig. 2 is a block diagram of the auxiliary power circuit of the present invention;

fig. 3A is a circuit block diagram of a first embodiment of the switching unit of the present invention;

FIG. 3B is a block diagram of a second embodiment of the switching unit of the present invention;

fig. 3C is a circuit block diagram of a third embodiment of the switching unit of the present invention;

fig. 4A is a circuit block diagram of a first embodiment of the bypass circuit of the present invention;

FIG. 4B is a block diagram of a second embodiment of a bypass circuit according to the present invention;

FIG. 5 is a detailed circuit diagram of the auxiliary power circuit of the present invention;

fig. 6A is a circuit configuration diagram of a first embodiment of the current adjustment unit of the present invention; and

fig. 6B is a circuit architecture diagram of a second embodiment of the current adjusting unit of the present invention.

In the figure:

100 … conversion system; 10 … switching circuit; 12 … first stage conversion unit; 14 … second stage conversion unit; a 142 … transformer; an N … induction coil; 16 … bus path; 162 … fire wire end; 164 ground end 164 …; 20 … control circuitry; 22. 22' … bypass circuit; 222 … voltage detection circuit; 224 … control unit; a 226 … switching unit; a D1 … first diode; 24 … energy storage capacitor; 242 … first end; 244 … second end; 26 … auxiliary power supply circuit; 262. 262 ', 262 ' ' …; a Dr … rectification unit; a Qp … power switch; 264 … voltage stabilizing circuit; r1 … first resistance; ZD1 … first voltage stabilization unit; 266 … charging path; d … drain; a source of S …; g … gate; 268. 268' … current adjusting unit; rs … current limiting resistor; a Qt … transistor; a C … collector; b … base electrode; e … emitter; a U1 … thyristor unit; an X … input; a Y … output; a Z … control terminal; ri … current detection resistance; ZD2 … second voltage stabilization unit; a second diode D2 …; a 200 … load; vin … input power; vo … output power; vbus … bus voltage; vw … operating voltage; vs … energy storage voltage; va … auxiliary voltage; vr … regulated voltage; vgs (th) … switch turn-on voltage; vg … gate voltage; vzd … nominal voltage; ic … charging current; sv … voltage signal.

Detailed Description

The present invention will be further described with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and can implement the present invention, but the embodiments are not to be construed as limiting the present invention.

Please refer to fig. 1, which is a block diagram of a switching system with a prolonged holding time according to the present invention. The switching system 100 includes a switching circuit 10 and a control circuit 20 with an extended holding time, the switching circuit 10 includes a first stage switching unit 12, a second stage switching unit 14 and a bus path 16. The first stage conversion unit 12 receives an input power Vin and is coupled to the second stage conversion unit 14 through a bus path 16, and the second stage conversion unit 14 is coupled to a load 200. The input power Vin may be an ac power or a dc power, if the input power Vin is an ac power, the first stage conversion unit 12 is an ac-dc converter, and if the input power Vin is a dc power, the first stage conversion unit 12 is a dc-dc converter. The second stage converting unit 14 may be a dc-to-ac converter or a dc-to-dc converter, similar to the first stage converting unit 12. The first stage conversion unit 12 converts the input power Vin into a bus voltage Vbus, and supplies the bus voltage Vbus to the second stage conversion unit 14 through a bus path 16. The second stage converting unit 14 converts the bus voltage Vbus into an output power Vo, and provides the output power Vo to the load 200. It should be noted that, in an embodiment of the present invention, the converting circuit 10 may be a power supply or a power supply device.

The control circuit 20 is coupled to the second stage conversion unit 14, the fire terminal 162 and the ground terminal 164 (i.e. ground terminal) of the bus path 16, and includes the bypass circuit 22, the energy storage capacitor 24 and the auxiliary power circuit 26. Specifically, the bypass circuit 22 is coupled to the line terminal 162 of the bus path 16 and the first terminal 242 of the storage capacitor 24, and the second terminal 244 of the storage capacitor 24 is coupled to the ground terminal 164. The auxiliary power circuit 26 is coupled to the bypass circuit 22 and the converting circuit 10, and receives the operating voltage Vw provided by the converting circuit 10. When the conversion circuit 10 normally converts the input power Vin into the output power Vo, the auxiliary power circuit 26 converts the operating voltage Vw into the energy storage voltage Vs, and provides the energy storage voltage Vs to the energy storage capacitor 24, so that the energy storage voltage Vs is established at two ends (242, 244) of the energy storage capacitor 24. When the conversion circuit 10 is abnormal (for example, but not limited to, the input power Vin is powered off or the first stage conversion unit 12 is damaged), the bus voltage Vbus will gradually decrease. When the bus voltage Vbus decreases to be equal to or less than the tank voltage Vs, the tank voltage Vs is supplied to the bus path 16 through the bypass circuit 22 to supplement the shortage of the bus voltage Vbus. So that the bus voltage Vbus can be maintained equal to or higher than a predetermined voltage for a hold time (hold up time). The predetermined voltage may be the lowest input voltage required for the second stage conversion unit 14 to operate normally.

Further, as shown in fig. 1, since the first terminal 242 of the energy storage capacitor 24 is not coupled to the live line terminal 162 of the bus path 16, the design of the capacitive withstand voltage of the energy storage capacitor 24 is not limited to a voltage maximum at least equal to the bus voltage Vbus, but the capacitive withstand voltage of the energy storage capacitor 24 is selected according to the design point voltage of the auxiliary power supply circuit 26. Since the design point voltage of the auxiliary power supply circuit 26 can be much lower than the bus voltage Vbus, the volume of the storage capacitor 24 can be greatly reduced, and the capacity utilization rate of the storage capacitor 24 can be greatly improved. It should be noted that, in an embodiment of the present invention, the voltage withstand of the capacitor of the storage capacitor 24 may be a stable or unstable voltage, but not exceed the maximum voltage of the bus voltage Vbus, except that it may be smaller than the maximum voltage of the bus voltage Vbus. In addition, in an embodiment of the present invention, the control circuit 20 may be included in the primary side or the secondary side of the first stage conversion unit 12 or the second stage conversion unit 14, or may not be included in the conversion circuit 10.

Fig. 2 is a block diagram of an auxiliary power circuit according to the present invention, and fig. 1 is also included in the block diagram. The auxiliary power supply circuit 26 includes a conversion unit 262, a voltage stabilizing circuit 264, and a charging path 266. The converting unit 262 is coupled to the converting circuit 10 and receives the operating voltage Vw provided by the converting circuit 10. The voltage stabilizing circuit 264 couples the converting unit 262 and the charging path 266, and the charging path 266 couples the energy storage capacitor 24 and the bypass circuit 22. The converting unit 262 converts the operating voltage Vw into the auxiliary voltage Va, and provides the auxiliary voltage Va to the voltage stabilizing circuit 264. The voltage stabilizing circuit 264 generates a regulated voltage Vr based on the auxiliary voltage Va, and the regulated voltage Vr conducts the charging path 266. At this time, the voltage stabilizing circuit 264 generates the charging current Ic according to the voltage difference between the regulated voltage Vr and the energy storage capacitor 24, and charges the energy storage capacitor 24 through the charging path 266, so that the energy storage voltage Vs is established between the two ends (242, 244) of the energy storage capacitor 24. When the energy storage voltage Vs is charged to the regulated voltage Vr minus the switch turn-on voltage vgs (th) of the charging path 266, the energy storage voltage Vs is balanced with the regulated voltage Vr, and the regulation circuit 264 stops charging the energy storage capacitor 24. Therefore, the magnitude of the tank voltage Vs is determined by the regulated voltage Vr. When the bus voltage Vbus is less than or equal to the tank voltage Vs, the tank voltage Vs is supplied to the bus path 16 through the bypass circuit 22.

Please refer to fig. 3A, which is a block diagram of a first embodiment of the conversion unit of the present invention, and fig. 1-2 are combined together. Taking the isolated converter as an example of the second stage conversion unit 14, the second stage conversion unit 14 includes a transformer 142. The transforming unit 262 is an induction coil N, and the induction coil N is coupled to the transformer 142. When the second stage converting unit 14 is normal, the transformer 142 generates the operating voltage Vw, and the operating voltage Vw is converted into the auxiliary voltage Va by way of electromagnetic coupling and the relationship between the number of turns of the induction coil N and the number of turns of the transformer 142. It should be noted that, in an embodiment of the present invention, if the auxiliary voltage Va induced by the induction coil N is not a stable dc source, the auxiliary voltage Va can be rectified into a stable dc source by the rectifying unit Dr shown in fig. 3A.

Fig. 3B is a block diagram of a second embodiment of the conversion unit of the present invention, which is combined with fig. 1-3A. The converting unit 262 'of the present embodiment is different from the converting unit 262 of fig. 3A in that the converting unit 262' is a switching type or linear power converter. The switching power converter, which may be a boost, buck or other converter, is configured to provide a set of programmable voltage range power converters and is coupled to the bus path 16. Since the converting unit 262 ' is coupled to the bus path 16, the converting unit 262 ' takes the bus voltage Vbus as the operating voltage Vw, and converts the operating voltage Vw into the auxiliary voltage Va by high-frequency switching of the internal power switch Qp of the converting unit 262 '.

Please refer to fig. 3C, which is a block diagram of a third embodiment of the conversion unit of the present invention, and fig. 1 to 3B are combined together. The converting unit 262 'of the present embodiment is different from the converting unit 262 of fig. 3A in that the converting unit 262' is coupled to the first stage converting unit 12, and the first stage converting unit 12 is an ac-dc converter or a dc-dc converter. When the first stage conversion unit 12 is an ac-dc converter, the input power Vin received by the first stage conversion unit 12 is an ac power, the conversion unit 262 ″ is coupled to a dc terminal behind an internal bridge rectifier of the ac-dc converter, and obtains a working voltage Vw according to the operation of the ac-dc converter, and the working voltage Vw is converted into an auxiliary voltage Va by a high-frequency switching manner of an internal power switch (not shown) of the conversion unit 262 ″. When the first stage conversion unit 12 is a dc-dc converter, the input power Vin received by the first stage conversion unit 12 is a dc power, the conversion unit 262 ″ is coupled to any dc terminal inside the dc-dc converter, and obtains a working voltage Vw according to the operation of the dc-dc converter, and converts the working voltage Vw into an auxiliary voltage Va by using a high-frequency switching manner of an internal power switch (not shown) of the conversion unit 262 ″.

It should be noted that, in an embodiment of the present invention, the implementation of the converting unit 262 is not limited to the above-mentioned fig. 3A, fig. 3B and fig. 3C, and all kinds of converting units capable of obtaining a stable dc source and coupling points of the converting units should be included in the scope of the present embodiment. For example, but not limited to, the converting unit 262 may also be a linear power converter (not shown). The linear power converter (not shown) is coupled to the bus path 16 or the first stage converting unit 12, and uses the bus voltage Vbus or a dc voltage inside the first stage converting unit 12 as the operating voltage Vw, so as to convert the operating voltage Vw into the auxiliary voltage Va in a linear conversion manner. In addition, in an embodiment of the present invention, the converting unit 262' of fig. 3C can also be coupled in the second stage converting unit 14 (i.e. the second stage converting unit 14 is also a dc-dc converter), and obtains the operating voltage Vw according to the operation of the second stage converting unit 14. The difference from fig. 3A is that the converting unit 262 ″ does not need to obtain the operating voltage Vw by means of the electromagnetic coupling of fig. 3A, but rather, obtains the operating voltage Vw by coupling any dc terminal inside the second stage converting unit 14.

Please refer to fig. 4A, which is a block diagram of a bypass circuit according to a first embodiment of the present invention, and fig. 1 to 3B are combined together. The bypass circuit 22 is a first diode D1, an anode of the first diode D1 is coupled to the energy storage capacitor 24, and a cathode of the first diode D1 is coupled to the bus path 16. When the bus voltage Vbus is less than or equal to the tank voltage Vs, the first diode D1 is biased in the positive direction, so that the tank voltage Vs supplements the bus voltage Vbus through the first diode D1. When the bus voltage Vbus is greater than the tank voltage Vs, the first diode D1 is reversely biased, so that the tank voltage Vs cannot supplement the bus voltage Vbus through the first diode D1.

Fig. 4B is a circuit block diagram of a second embodiment of the bypass circuit of the present invention, which is combined with fig. 1 to 4A. The bypass circuit 22 'of the present embodiment is different from the bypass circuit 22 of fig. 4A in that the bypass circuit 22' includes a voltage detection circuit 222, a control unit 224 and a switch unit 226. The voltage detection circuit 222 is coupled to the bus path 16 and detects a voltage signal Sv of the bus voltage Vbus. The control unit 224 is coupled to the voltage detection circuit 222, and the switch unit 226 is coupled to the bus path 16, the energy storage capacitor 24 and the control unit 224. The control unit 224 receives the voltage signal Sv and determines whether to turn on the switch unit 226 according to the voltage signal Sv. When the control unit 224 determines that the bus voltage Vbus is smaller than the voltage detection circuit reference voltage according to the voltage signal Sv, the control unit 224 controls the switch unit 226 to be turned on, so that the storage voltage Vs supplements the bus voltage Vbus through the switch unit 226. When the control unit 224 determines that the bus voltage Vbus is greater than the voltage detection circuit reference voltage according to the voltage signal Sv, the control unit 224 controls the switch unit 226 to be turned off, so that the energy storage capacitor 24 and the bus path 16 are disconnected. It should be noted that, in an embodiment of the present invention, the action point of the switch unit 226 is not limited to any voltage, and the control unit 224 can determine the action point of the switch unit 226 according to the use condition. That is, the control unit 224 can set the threshold voltage, when the line voltage Vbus is lower than the threshold voltage, the control unit 224 controls the switch unit 226 to be turned on, and the bus voltage Vbus is not necessarily greater than the energy storage voltage Vs, and the switch unit 226 is turned off. In addition, if the control unit 224 can determine the operating point at which the switch unit 226 is turned on according to the usage conditions, the withstand voltage of the storage capacitor 24 can also be adjusted according to the setting of the threshold voltage.

Fig. 5 is a detailed circuit architecture diagram of the auxiliary power circuit of the present invention, which is combined with fig. 1 to 4B. The voltage regulator circuit 264 includes a first resistor R1 and a first voltage regulation unit ZD1, the first resistor R1 is coupled to the conversion unit 262 and the first voltage regulation unit ZD1, and the first voltage regulation unit ZD1 is coupled to the ground. The charging path 266 is a Metal Oxide Semiconductor Field Effect Transistor (MOSFET) including a drain D, a source S and a gate G, and the drain D is coupled to the first resistor R1 and the converting unit 262. The gate G of the mosfet is coupled to the first resistor R1 and the first voltage stabilizing unit ZD1, and the source S is coupled to the energy storage capacitor 24 and the bypass circuit 22. The first resistor R1 is used for current limiting, the auxiliary voltage Va establishes a regulated voltage Vr in the first voltage regulation unit ZD1, and the regulated voltage Vr establishes a switch-on voltage vgs (th) between the gate G and the source S of the mosfet, so that the drain D and the source S of the mosfet are turned on. At this time, the voltage stabilizing circuit 264 generates the charging current Ic according to the voltage difference between the regulated voltage Vr and the energy storage capacitor 24, and the drain D and the source S are turned on to charge the energy storage capacitor 24. Wherein, the energy storage voltage Vs is the regulated voltage Vr minus the switch turn-on voltage Vgs (th) of the gate G and the source S.

As shown in fig. 5, the auxiliary power circuit 26 further includes a current adjusting unit 268, a second voltage stabilizing unit ZD2 and a second diode D2. The current adjusting unit 268 is coupled between the voltage stabilizing circuit 264 and the drain D of the mosfet, and is used for adjusting the charging current Ic for charging the energy storage capacitor 24 to prevent the energy storage capacitor 24 from being damaged due to overcurrent. The second voltage stabilizing unit ZD2 is coupled between the source S and the gate G of the mosfet, and establishes a rated voltage Vzd between the source S and the gate G to limit the gate voltage Vg to be less than or equal to the rated voltage Vzd and prevent the mosfet from being damaged due to overvoltage. Specifically, the gate voltage Vg generally exceeds, for example, but not limited to, 40V (depending on the kind of mosfet), which may result in breakdown between the source S and the gate G, resulting in damage to the mosfet. Therefore, the second voltage stabilizing unit ZD2 clamps the gate voltage Vg to be lower than 40V (for example, but not limited to, 20V) to avoid the gate voltage Vg from being too high and causing damage to the mosfet.

The second diode D2 is coupled to the first resistor R1, the first voltage regulation unit ZD1, the gate G of the mosfet, the second voltage regulation unit ZD2 and the fire wire end 162 of the bus path 16, and when the bus voltage Vbus is smaller than the regulated voltage Vr of the first voltage regulation unit ZD1, the second diode D2 is biased forward, so that the regulated voltage Vr of the first voltage regulation unit ZD1 is released to the bus path 16. At this time, the regulated voltage Vr is lowered to be substantially equal to the bus voltage Vbus. Since the regulated voltage Vr is substantially equal to the bus voltage Vbus, the storage voltage Vs on the storage capacitor 24 decreases with the decrease of the regulated voltage Vr, so as to avoid the transient excessive energy from flowing to the bus path 16 due to the excessive voltage difference between the storage voltage Vs and the bus voltage Vbus. Further, since the second stage converting unit 14 usually belongs to a switching power converter, when the input end (i.e. on the bus path 16) of the second stage converting unit 14 is lower than the energy storage voltage Vs and does not directly drop to zero, the auxiliary voltage Va is prevented from continuously releasing energy to the bus voltage Vbus, which causes extra energy to be accumulated at the input end and causes energy waste. Therefore, reducing the regulated voltage Vr to be substantially equal to the bus voltage Vbus may increase the overall efficiency of the conversion system 100. In addition, the second diode D2 may also be coupled to the power output end of the second stage conversion unit 14 (as shown in fig. 1, the positive end of the output power Vo) for avoiding excessive transient energy from being discharged to the power output end due to an excessive voltage difference between the energy storage voltage Vs and the output power Vo. The circuit operation and function are the same as the second diode D2 coupled to the live line terminal 162 of the bus path 16, and will not be described herein again. It should be noted that, in an embodiment of the present invention, the detailed circuit architecture of the auxiliary power circuit 26 may have various implementations of circuits, components, controllers, and even software and hardware. Therefore, circuits, components, controllers, software and hardware for achieving the above-mentioned circuit function should be included in the scope of the present embodiment.

Fig. 6A is a circuit architecture diagram of a current adjusting unit according to a first embodiment of the present invention, and fig. 1 to 5 are combined. The current adjusting unit 268 may be a current limiting resistor Rs, one end of which is coupled to the first resistor R1, and the other end of which is coupled to the drain D of the mosfet. The current limiting resistor Rs limits the charging current Ic for charging the energy storage capacitor 24, so as to avoid the decrease of the service life caused by the instantaneous large current of the energy storage capacitor 24. It should be noted that, in an embodiment of the present invention, the current limiting resistor Rs may also be coupled after the charging path 266 or before the voltage stabilizing circuit 264. That is, the current limiting resistor Rs may be coupled to the path from the transforming unit 262 to the energy storage capacitor 24.

Fig. 6B is a circuit structure diagram of a current adjusting unit according to a second embodiment of the present invention, and fig. 1 to 6A are combined. The difference between the current adjusting unit 268 'of the present embodiment and the current adjusting unit 268 of fig. 6A is that the current adjusting unit 268' includes a transistor Qt, a thyristor U1 and a current detection resistor Ri. The transistor Qt includes a collector C, a base B, and an emitter E, and the thyristor U1 includes an input terminal X, an output terminal Y, and a control terminal Z. The collector C of the transistor Qt is coupled to the regulator 264, and the base B is coupled to the input X of the thyristor U1 and the regulator 264. One end of the current detection resistor Ri is coupled to the emitter E of the transistor Qt and the control terminal Z of the thyristor U1, and the other end of the current detection resistor Ri is coupled to the output terminal Y of the thyristor U1 and the source S of the mosfet. When the charging current Ic flows through the current detection resistor Ri, a voltage difference is generated across the current detection resistor Ri. The thyristor U1 obtains the voltage difference between the two ends of the current detection resistor Ri through the output terminal Y and the control terminal Z, and adjusts the current at the input terminal X of the thyristor U1 according to the voltage difference. At this time, since the transistor Qt has a function of adjusting the emitter E current by the base B current, when the current at the input terminal X of the thyristor U1 is adjusted, the current at the emitter E of the transistor Qt is also adjusted. Therefore, when the charging current Ic is too large, the voltage difference between the two ends of the current detection resistor Ri becomes large, so that the current at the input terminal X of the thyristor U1 is reduced, and the current at the emitter E of the transistor Qt is reduced. Moreover, when the charging current Ic becomes smaller, the voltage difference between the two ends of the current detection resistor Ri becomes smaller, so that the current at the input terminal X of the thyristor U1 is increased, and the current at the emitter E of the transistor Qt is increased. So that the thyristor U1 controls the transistor Qt to provide the charging current Ic with a fixed current value to charge the energy storage capacitor 24 according to the voltage drop of the current detection resistor Ri. It should be noted that, in an embodiment of the present invention, the current adjusting units 268, 268' are not limited to be formed by the above components. In other words, it can also be achieved by using, for example but not limited to, a linear Constant Current Regulator (CCR), a constant current diode (CRD), or a controller with circuitry. Therefore, any component or circuit having the current adjusting function should be included in the scope of the present embodiment. In addition, since the current adjusting unit 268 'includes the transistor Qt, the thyristor U1 and the current detection resistor Ri, the function of the charging path 266 can be replaced by the current adjusting unit 268'. That is, the current adjusting unit 268 'is the charging path 266, and the current detecting resistor Ri in the current adjusting unit 268' is directly coupled to the first end 242 of the energy storage capacitor 24, and the current Ic is adjusted by the transistor Qt, so that the energy storage capacitor 24 establishes the energy storage voltage Vs. Alternatively, the charging path 266 is a diode component (not shown). The anode of the diode is coupled to the current detection resistor Ri, and the cathode of the diode is coupled to the energy storage capacitor 24.

The above-mentioned embodiments are merely preferred embodiments for fully illustrating the present invention, and the scope of the present invention is not limited thereto. Equivalent substitutes or changes made by the technical personnel in the technical field on the basis of the utility model are all within the protection scope of the utility model. The protection scope of the present invention is subject to the claims.

Claims (19)

1. A control circuit with extended hold time, coupled to a bus path of a switching circuit, the control circuit comprising:

a bypass circuit coupled to a line terminal of the bus path;

an energy storage capacitor including a first end and a second end, wherein the first end is coupled to the bypass circuit, and the second end is coupled to a ground terminal of the bus path; and

an auxiliary power circuit coupled to the bypass circuit and the conversion circuit;

the auxiliary power supply circuit provides an energy storage voltage to the energy storage capacitor according to a working voltage provided by the conversion circuit; when a bus voltage of the bus path is less than or equal to the energy storage voltage, the energy storage voltage is provided to the bus path through the bypass circuit, so that the bus voltage is greater than or equal to a predetermined voltage within a holding time.

2. The control circuit with extended hold-up time of claim 1, wherein the auxiliary power circuit comprises:

a conversion unit coupled to the conversion circuit;

a voltage stabilizing circuit coupled to the converting unit; and

a charging path coupled to the voltage stabilizing circuit, the energy storage capacitor and the bypass circuit;

the conversion unit converts the working voltage into an auxiliary voltage, and the voltage stabilizing circuit generates a voltage stabilizing voltage according to the auxiliary voltage; the charging path is conducted by the stabilized voltage, and the stabilized voltage charges the energy storage capacitor through the charging path, so that the energy storage capacitor establishes the energy storage voltage.

3. The control circuit of claim 2, wherein the converting unit is an induction coil coupled to a transformer of the converting circuit, and the operating voltage of the transformer is converted into the auxiliary voltage by electromagnetic coupling.

4. The control circuit of claim 2, wherein the converting unit is a switching power converter coupled to the bus path and using the bus voltage as the operating voltage to convert the operating voltage into the auxiliary voltage.

5. The control circuit of claim 2, wherein the converting unit is a linear power converter coupled to the bus path and using the bus voltage as the operating voltage to convert the operating voltage into the auxiliary voltage.

6. The control circuit of claim 2, wherein the converting circuit comprises an ac-to-dc converter; the conversion unit is coupled to the ac-dc converter and obtains the working voltage according to the operation of the ac-dc converter to convert the working voltage into the auxiliary voltage.

7. The control circuit with extended hold-up time of claim 2, wherein the conversion circuit comprises a dc-to-dc converter; the conversion unit is coupled to the DC-DC converter and obtains the working voltage according to the operation of the DC-DC converter so as to convert the working voltage into the auxiliary voltage.

8. The control circuit of claim 1, wherein the bypass circuit is a first diode; when the bus voltage is less than or equal to the energy storage voltage, the first diode is forward biased, and when the bus voltage is greater than the energy storage voltage, the first diode is reverse biased.

9. The control circuit with extended hold time of claim 1, wherein the bypass circuit comprises:

a voltage detection circuit coupled to the bus path;

a control unit coupled to the voltage detection circuit;

a switch unit coupled to the bus path, the energy storage capacitor and the control unit;

the voltage detection circuit detects a voltage signal of the bus voltage, and the control unit judges whether to conduct the switch unit according to the voltage signal; when the switch unit is conducted, the energy storage voltage supplements the bus voltage through the switch unit.

10. The control circuit with extended hold-up time of claim 2, wherein the auxiliary power circuit further comprises:

a current limiting resistor coupled to the voltage stabilizing circuit and the charging path;

the current limiting resistor limits a charging current for charging the energy storage capacitor.

11. The control circuit with extended hold-up time of claim 2, wherein the auxiliary power circuit further comprises:

a transistor coupled to the voltage regulator circuit;

a thyristor unit coupled to the voltage regulator circuit and the transistor; and

a current detection resistor coupled to the transistor and the thyristor;

the thyristor controls the transistor to provide a charging current with a fixed current value according to the voltage drop of the current detection resistor so as to charge the energy storage capacitor.

12. The control circuit of claim 11, wherein a current adjusting unit formed by the transistor, the thyristor and the current detecting resistor is the charging path.

13. The control circuit of claim 11, wherein the charge path is a diode device.

14. The control circuit of claim 2, wherein the energy storage voltage is the regulated voltage minus a switch turn-on voltage of the charging path.

15. The control circuit with extended hold-up time of claim 2, wherein the auxiliary power circuit further comprises:

a voltage stabilizing unit coupled to the voltage stabilizing circuit, the charging path and the energy storage capacitor;

the voltage stabilizing unit limits a gate voltage of the charging path to be less than or equal to a rated voltage.

16. The control circuit of claim 1, wherein a capacitance withstand voltage of the energy storage capacitor is less than a voltage maximum of the bus voltage.

17. The control circuit with extended hold-up time of claim 2, wherein the auxiliary power circuit further comprises:

a second diode coupled to the voltage regulator circuit and the charging path;

when the bus voltage is less than the regulated voltage, the second diode is forward biased, so that the regulated voltage is released to the bus path.

18. The control circuit with extended hold-up time of claim 2, wherein the auxiliary power circuit further comprises:

a second diode coupled to the voltage regulator circuit and a power output terminal of the conversion circuit;

when an output power supply output by the conversion circuit is smaller than the regulated voltage, the second diode is forward biased, so that the regulated voltage is released to the power supply output end.

19. A switching system having an extended hold time, comprising:

a conversion circuit, comprising:

a first stage converting unit for converting an input power into a bus voltage; and

a second stage conversion unit coupled to the first stage conversion unit via a bus path and converting the bus voltage into an output power; and

a control circuit, coupled to the bus path, and comprising:

a bypass circuit coupled to a line terminal of the bus path;

an energy storage capacitor including a first end and a second end, wherein the first end is coupled to the bypass circuit, and the second end is coupled to a ground terminal of the bus path; and

an auxiliary power circuit coupled to the bypass circuit and the conversion circuit;

the auxiliary power supply circuit provides an energy storage voltage to the energy storage capacitor according to a working voltage provided by the conversion circuit; when a bus voltage of the bus path is less than or equal to the energy storage voltage, the energy storage voltage is provided to the bus path through the bypass circuit, so that the bus voltage is greater than or equal to a predetermined voltage within a holding time.

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