Control circuit with extended holding time and conversion system thereof

Abstract

The present invention provides a control circuit with extended holding time and a conversion system thereof. The control circuit is coupled to the bus path of the conversion circuit, and the control circuit includes: a bypass circuit, an energy storage capacitor and an 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 a predetermined voltage within the holding time. Thus, a control circuit with extended holding time and a conversion system with extended holding time are provided. In addition to using the control circuit to control the energy storage capacitor to extend the holding time, a special structural design can be used to reduce the withstand voltage of the energy storage capacitor, thereby reducing the volume of the energy storage capacitor and saving costs.

Description

Technical Field

[0001] The present invention relates to a control circuit with extended holding time, and more particularly to a control circuit with extended holding time and a conversion system thereof, which can maintain a voltage greater than or equal to a predetermined voltage during the holding time. Background Art

[0002] In recent years, as electronic products have become more and more popular, and in order to stabilize the power quality of electronic products, the power supply requirements for power supply devices have gradually increased with the popularity of electronic products and the emphasis on power quality. The safety regulations for power supply devices stipulate that when the power supply device is powered on by the power supply device to electronic products, if the power supply device is powered off, the power supply device must still maintain continuous power output for a short period of time.

[0003] In order to meet the requirements of safety regulations, a common practice is to increase the capacity of the energy storage capacitor at the output end of the power supply device. The larger the capacity of the energy storage capacitor, the longer the maintenance time can be maintained, which can meet the requirements of safety regulations. However, this practice will cause the volume of the energy storage capacitor to increase due to the required capacity of the energy storage capacitor. In addition, since the energy storage capacitor is directly coupled to the live wire terminal and the ground wire terminal of the output end of the power supply device, the withstand voltage of the energy storage capacitor must also be greater than the output voltage of the output end of the power supply device (for example but not limited to 400V) to avoid damage to the energy storage capacitor due to insufficient withstand voltage. However, increasing the withstand voltage of the energy storage capacitor also means that the volume of the energy storage capacitor will also increase.

[0004] Therefore, how to design a control circuit with extended holding time and a conversion system with extended holding time, in addition to using the control circuit to control the energy storage capacitor to extend the holding time, can also use a special structural design to reduce the withstand voltage of the energy storage capacitor, thereby reducing the volume of the energy storage capacitor and saving costs, is a technical problem that the inventor needs to solve. Summary of the invention

[0005] The object of the present invention is to solve the above-mentioned problem and provide a control circuit and a conversion system thereof with extended holding time.

[0006] To achieve the above-mentioned purpose, the present invention has a control circuit with extended maintenance time coupled to the bus path of the conversion circuit, and the control circuit includes: a bypass circuit, coupled to the live wire end of the bus path. An energy storage capacitor, including a first end and a second end, the first end is coupled to the bypass circuit, and the second end is coupled to the ground wire end of the bus path. And an auxiliary power supply circuit, coupling the bypass circuit and the conversion circuit. Among them, 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 maintenance time.

[0007] In one embodiment, the auxiliary power supply circuit includes: a conversion unit coupled to the conversion circuit; a voltage stabilizing circuit coupled to the conversion unit; and a charging path coupled to the voltage stabilizing circuit, the energy storage capacitor and the bypass circuit. The conversion unit converts the operating voltage into an auxiliary voltage, and the voltage stabilizing circuit generates a regulated voltage according to the auxiliary voltage; the regulated voltage conducts the charging path, and the regulated voltage charges the energy storage capacitor through the charging path, so that the energy storage capacitor establishes an energy storage 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.

[0008] In one embodiment, the conversion unit is an induction coil, which is coupled to a transformer of the conversion circuit and converts the working voltage of the transformer into the auxiliary voltage by electromagnetic coupling.

[0009] In one embodiment, the conversion unit is a switching power converter, which is coupled to a bus path and uses the bus voltage as a working voltage to convert the working voltage into an auxiliary voltage.

[0010] In one embodiment, the conversion unit is a linear power converter, which is coupled to a bus path and uses the bus voltage as a working voltage to convert the working voltage into an auxiliary voltage.

[0011] In one embodiment, the conversion circuit includes an AC-DC converter; the conversion unit is coupled to the AC-DC converter and obtains a working voltage according to the operation of the AC-DC converter to convert the working voltage into an auxiliary voltage.

[0012] In one embodiment, the conversion circuit includes 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 to convert the working voltage into an auxiliary voltage.

[0013] 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.

[0014] In one embodiment, the bypass circuit includes: a voltage detection circuit coupled to a 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 determines whether to turn on 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.

[0015] In one embodiment, the auxiliary power circuit further includes: a current limiting resistor coupled to the voltage stabilizing circuit and the charging path, wherein the current limiting resistor limits the charging current for charging the energy storage capacitor.

[0016] In one embodiment, the auxiliary power circuit further includes: a transistor coupled to the voltage stabilizing circuit, a thyristor coupled to the voltage stabilizing 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 of a fixed current value to charge the energy storage capacitor according to the voltage drop of the current detection resistor.

[0017] In one embodiment, the current adjustment unit composed of the transistor, the thyristor unit and the current detection resistor is the charging path.

[0018] In one embodiment, the charging path is a diode element.

[0019] In one embodiment, the energy storage voltage is the regulated voltage minus the switch-on voltage of the charging path.

[0020] In one embodiment, the auxiliary power circuit further includes: a voltage stabilizing unit coupled to the voltage stabilizing circuit, the charging path and the energy storage capacitor, wherein the voltage stabilizing unit limits the gate voltage of the charging path to be less than or equal to the rated voltage.

[0021] In one embodiment, the capacitance withstand voltage of the energy storage capacitor is less than the maximum voltage of the bus voltage.

[0022] In one embodiment, the auxiliary power circuit further includes: a second diode coupled to the voltage stabilization 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.

[0023] In order to achieve the above-mentioned purpose, the present invention further provides a conversion system to overcome the problems of the known technology. Therefore, the conversion system of the present invention includes: a conversion circuit, including: a first-stage conversion unit, which converts the input power into a bus voltage. And a second-stage conversion unit, coupled to 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: a bypass circuit, coupled to the live end of the bus path. An energy storage capacitor, including a first end and a second end, the first end is coupled to the bypass circuit, and the second end is coupled to the ground end of the bus path. And an auxiliary power supply circuit, coupling the bypass circuit and the conversion circuit. Among them, 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 maintenance time. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A circuit block diagram of a conversion system with extended holding time according to the present invention;

[0025] Figure 2 is a circuit block diagram of the auxiliary power supply circuit of the present invention;

[0026] Figure 3A is a circuit block diagram of a first embodiment of a conversion unit of the present invention;

[0027] Figure 3B is a circuit block diagram of a second embodiment of a conversion unit of the present invention;

[0028] Figure 3C is a circuit block diagram of a third embodiment of a conversion unit of the present invention;

[0029] Figure 4A is a circuit block diagram of a first embodiment of a bypass circuit of the present invention;

[0030] Figure 4B is a circuit block diagram of a second embodiment of a bypass circuit of the present invention;

[0031] Figure 5 is a detailed circuit structure diagram of the auxiliary power supply circuit of the present invention;

[0032] Fig. 6A is a circuit structure diagram of a first embodiment of a current adjustment unit of the present invention; and

[0033] Figure 6B FIG. 4 is a circuit structure diagram of a second embodiment of a current adjustment unit of the present invention.

[0034] In the figure:

[0035] 100…conversion system; 10…conversion circuit; 12…first stage conversion unit; 14…second stage conversion unit; 142…transformer; N…induction coil; 16…bus path; 162…live terminal; 164…ground terminal; 20…control circuit; 22, 22'…bypass circuit; 222…voltage detection circuit; 224…control unit; 226…switch unit; D1…first diode; 24…energy storage capacitor; 242…first terminal; 244…second terminal; 26…auxiliary power supply circuit; 262, 262', 262''…conversion unit; Dr…rectifier unit; Qp…power switch; 264…voltage stabilizing circuit; R1…first resistor; ZD1…first voltage stabilizing unit; 266 …charging path; D…drain; S…source; G…gate; 268, 268'…current adjustment unit; Rs…current limiting resistor; Qt…transistor; C…collector; B…base; E…emitter; U1…thyristor; X…input end; Y…output end; Z…control end; Ri…current detection resistor; ZD2…second voltage stabilizing unit; D2…second diode; 200…load; Vin…input power supply; Vo…output power supply; Vbus…bus voltage; Vw…working voltage; Vs…energy storage voltage; Va…auxiliary voltage; Vr…stabilized voltage; Vgs(th)…switch on-voltage; Vg…gate voltage; Vzd…rated voltage; Ic…charging current; Sv…voltage signal. DETAILED DESCRIPTION

[0036] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0037] See also Figure 1The circuit block diagram of the conversion system with extended holding time of the present invention is shown. The conversion system 100 includes a conversion circuit 10 and a control circuit 20 with extended holding time. The conversion circuit 10 includes a first-stage conversion unit 12, a second-stage conversion unit 14 and a bus path 16. The first-stage conversion unit 12 receives an input power source Vin, and is coupled to the second-stage conversion unit 14 through the bus path 16, and the second-stage conversion unit 14 is coupled to a load 200. The input power source Vin can be an AC power source or a DC power source. If the input power source Vin is an AC power source, the first-stage conversion unit 12 is an AC-to-DC converter. If the input power source Vin is a DC power source, the first-stage conversion unit 12 is a DC-to-DC converter. The second-stage conversion unit 14 is similar to the first-stage conversion unit 12 and can be a DC-to-AC converter or a DC-to-DC converter. The first-stage conversion unit 12 converts the input power source Vin into a bus voltage Vbus, and provides the bus voltage Vbus to the second-stage conversion unit 14 through the bus path 16. The second stage conversion unit 14 converts the bus voltage Vbus into an output power Vo, and provides the output power Vo to the load 200. It is worth mentioning that in an embodiment of the present invention, the conversion circuit 10 can be a power supply or a power supply device.

[0038] The control circuit 20 is coupled to the second-stage conversion unit 14, the live terminal 162 and the ground terminal 164 (i.e., the ground terminal) of the bus path 16, and includes a bypass circuit 22, an energy storage capacitor 24, and an auxiliary power circuit 26. Specifically, the bypass circuit 22 is coupled to the live terminal 162 of the bus path 16 and the first end 242 of the energy storage capacitor 24, and the second end 244 of the energy storage capacitor 24 is coupled to the ground terminal 164. The auxiliary power circuit 26 is coupled to the bypass circuit 22 and the conversion circuit 10, and receives the working voltage Vw provided by the conversion 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 working 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 both 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 supply 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 less than or equal to the energy storage voltage Vs, the energy storage voltage Vs is provided to the bus path 16 through the bypass circuit 22 to supplement the shortage of the bus voltage Vbus. The bus voltage Vbus can be maintained greater than or equal to the predetermined voltage within the hold up time. The predetermined voltage can be the minimum input voltage required for the normal operation of the second-stage conversion unit 14.

[0039] Furthermore, if Figure 1As shown, since the first end 242 of the energy storage capacitor 24 is not coupled to the live wire end 162 of the bus path 16, the capacitor withstand voltage design of the energy storage capacitor 24 does not need to be limited to at least equal to the maximum voltage of the bus voltage Vbus, but the capacitor 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 smaller than the bus voltage Vbus, the volume of the energy storage capacitor 24 can be greatly reduced to greatly improve the capacitor utilization of the energy storage capacitor 24. It is worth mentioning that in one embodiment of the present invention, the capacitor withstand voltage of the storage capacitor 24 can be less than the maximum voltage of the bus voltage Vbus, and can also be a stable or unstable voltage, but will not exceed the maximum voltage of the bus voltage Vbus. In addition, in one embodiment of the present invention, the control circuit 20 can be included in the primary side or secondary side of the first-stage conversion unit 12 or inside the second-stage conversion unit 14, and can also be not included in the conversion circuit 10.

[0040] See also Figure 2 The circuit block diagram of the auxiliary power supply circuit of the present invention is shown in FIG. Figure 1 . The auxiliary power supply circuit 26 includes a conversion unit 262, a voltage regulator circuit 264 and a charging path 266. The conversion unit 262 is coupled to the conversion circuit 10, and receives the working voltage Vw provided by the conversion circuit 10. The voltage regulator circuit 264 couples the conversion unit 262 and the charging path 266, and the charging path 266 couples the energy storage capacitor 24 and the bypass circuit 22. The conversion unit 262 converts the working voltage Vw into an auxiliary voltage Va, and provides the auxiliary voltage Va to the voltage regulator circuit 264. The voltage regulator circuit 264 generates a regulated voltage Vr according to the auxiliary voltage Va, and the regulated voltage Vr turns on the charging path 266. At this time, the voltage regulator circuit 264 generates a 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 at both 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 conduction voltage Vgs(th) of the charging path 266, the energy storage voltage Vs is balanced with the regulated voltage Vr, and the voltage stabilizing circuit 264 stops charging the energy storage capacitor 24. Therefore, the magnitude of the energy storage voltage Vs is determined by the regulated voltage Vr. When the bus voltage Vbus is less than or equal to the energy storage voltage Vs, the energy storage voltage Vs is provided to the bus path 16 through the bypass circuit 22.

[0041] See also Figure 3A FIG. 1 is a circuit block diagram of a first embodiment of a conversion unit of the present invention, and is also referred to in conjunction with FIG. Figure 1~2. Taking the second-stage conversion unit 14 as an isolated converter as an example, the second-stage conversion unit 14 includes a transformer 142. The conversion unit 262 is an induction coil N, and the induction coil N is coupled to the transformer 142. When the second-stage conversion unit 14 is normal, the transformer 142 generates a working voltage Vw, and the working voltage Vw is converted into an auxiliary voltage Va in an electromagnetic coupling manner and the relationship between the number of turns of the induction coil N and the transformer 142. It is worth mentioning that in one embodiment of the present invention, if the auxiliary voltage Va induced by the induction coil N is not a stable DC source, it can be Figure 3A The rectifier unit Dr shown rectifies into a stable DC source.

[0042] See also Figure 3B FIG. 1 is a circuit block diagram of a second embodiment of a conversion unit of the present invention, and is also referred to in conjunction with FIG. Figure 1~3A The conversion unit 262' of this embodiment is Figure 3A The difference between the conversion unit 262 and the conversion unit 262 is that the conversion unit 262' is a switching or linear power converter. The switching power converter can be, for example, a boost, buck or other architecture converter, and its purpose is to provide a set of designable voltage range power converters, and the switching power converter is coupled to the bus path 16. Since the conversion unit 262' is coupled to the bus path 16, the conversion unit 262' uses the bus voltage Vbus as the working voltage Vw, and uses the high-frequency switching of the internal power switch Qp of the conversion unit 262' to convert the working voltage Vw into the auxiliary voltage Va.

[0043] See also Figure 3C FIG. 1 is a circuit block diagram of a third embodiment of a conversion unit of the present invention, and is also referred to in conjunction with FIG. Figures 1 to 3B The conversion unit 262'' of this embodiment is Figure 3A The difference between the conversion unit 262 of the first stage conversion unit 12 and the first stage conversion unit 12 is that the conversion unit 262 ″ is coupled to the first stage conversion unit 12, and the first stage conversion unit 12 is an AC to DC converter or a DC to DC converter. When the first stage conversion unit 12 is an AC to DC converter, the input power Vin received by the first stage conversion unit 12 is an AC power source, the conversion unit 262 ″ is coupled to the DC terminal after the internal bridge rectifier of the AC to DC converter, and obtains the working voltage Vw according to the operation of the AC to DC converter, and converts the working voltage Vw into the auxiliary voltage Va by using the high-frequency switching method of the internal power switch (not shown) of the conversion unit 262 ″. When the first stage conversion unit 12 is a DC to DC converter, the input power Vin received by the first stage conversion unit 12 is a DC power source, the conversion unit 262 ″ is coupled to any DC terminal inside the DC to DC converter, and obtains the working voltage Vw according to the operation of the DC to DC converter, and converts the working voltage Vw into the auxiliary voltage Va by using the high-frequency switching method of the internal power switch (not shown) of the conversion unit 262 ″.

[0044] It is worth mentioning that in one embodiment of the present invention, the implementation of the conversion unit 262 is not limited to the above Figure 3A , Figure 3B and Figure 3C , all types of conversion units that can obtain a stable DC source, and the coupling points of the conversion units, should be included in the scope of this embodiment. For example but not limited to, the conversion unit 262 can 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 conversion unit 12, and uses the bus voltage Vbus or the DC voltage inside the first-stage conversion unit 12 as the working voltage Vw, so as to convert the working voltage Vw into the auxiliary voltage Va in a linear conversion manner. In addition, in one embodiment of the present invention, Figure 3C The conversion unit 262'' can also be coupled to the second-stage conversion unit 14 (that is, the second-stage conversion unit 14 is also a DC-DC converter), and obtains the working voltage Vw according to the operation of the second-stage conversion unit 14. Figure 3A The difference is that the conversion unit 262'' does not need to be Figure 3A The working voltage Vw is obtained not by electromagnetic coupling, but by coupling to any DC terminal inside the second-stage conversion unit 14.

[0045] See also Figure 4A FIG. 1 is a circuit block diagram of a first embodiment of the bypass circuit of the present invention, and is also referred to in conjunction with FIG. Figures 1 to 3B The bypass circuit 22 is a first diode D1, and the anode of the first diode D1 is coupled to the energy storage capacitor 24, and the 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 energy storage voltage Vs, the first diode D1 is forward biased, so that the energy storage voltage Vs supplements the bus voltage Vbus through the first diode D1. When the bus voltage Vbus is greater than the energy storage voltage Vs, the first diode D1 is reverse biased, so that the energy storage voltage Vs cannot supplement the bus voltage Vbus through the first diode D1.

[0046] See also Figure 4B FIG. 1 is a circuit block diagram of a second embodiment of the bypass circuit of the present invention, and is also referred to in conjunction with FIG. Figure 1~4A The bypass circuit 22' of this embodiment is Figure 4AThe difference between the bypass circuit 22 of FIG. 1 and FIG. 2 is 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 less than the reference voltage of the voltage detection circuit according to the voltage signal Sv, the control unit 224 controls the switch unit 226 to turn on, so that the energy 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 reference voltage of the voltage detection circuit according to the voltage signal Sv, the control unit 224 controls the switch unit 226 to not turn on, so that the energy storage capacitor 24 and the bus path 16 are disconnected. It is worth mentioning that in one embodiment of the present invention, the switching point of the switch unit 226 is not limited to any voltage, and the control unit 224 can determine the switching point of the switch unit 226 according to the use conditions. That is, the control unit 224 can set the threshold voltage, and the control unit 224 controls the switch unit 226 to be turned on only when the line voltage Vbus is lower than the threshold voltage, and the bus voltage Vbus does not have to be greater than the energy storage voltage Vs for the switch unit 226 to be turned off. In addition, if the control unit 224 can determine the switching point of the switch unit 226 according to the use conditions, the capacitor withstand voltage of the energy storage capacitor 24 can also be adjusted with the setting of the threshold voltage.

[0047] See also Figure 5 The detailed circuit structure diagram of the auxiliary power circuit of the present invention is shown in FIG. Figures 1 to 4BThe voltage regulator circuit 264 includes a first resistor R1 and a first voltage regulator unit ZD1. The first resistor R1 is coupled to the conversion unit 262 and the first voltage regulator unit ZD1, and the first voltage regulator unit ZD1 is coupled to the ground terminal. The charging path 266 is a metal oxide semiconductor field effect transistor (MOSFET). The MOSFET includes a drain D, a source S and a gate G, and the drain D is coupled to the first resistor R1 and the conversion unit 262. The gate G of the MOSFET is coupled to the first resistor R1 and the first voltage regulator 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 regulator unit ZD1, and the regulated voltage Vr enables the gate G and the source S of the MOSFET to establish a switch-on voltage Vgs(th) to turn on the drain D and the source S of the MOSFET. At this time, the voltage regulator circuit 264 generates a 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. The energy storage voltage Vs is the regulated voltage Vr minus the switch conduction voltage Vgs(th) of the gate G and the source S.

[0048] like Figure 5 As shown, the auxiliary power circuit 26 further includes a current adjustment unit 268, a second voltage stabilizing unit ZD2 and a second diode D2. The current adjustment unit 268 is coupled between the voltage stabilizing circuit 264 and the drain D of the MOSFET, and is used to adjust the size of the charging current Ic for charging the energy storage capacitor 24 to avoid damage to the energy storage capacitor 24 due to overcurrent. The second voltage stabilizing unit ZD2 is coupled between the source S and the gate G of the MOSFET, and a rated voltage Vzd is established 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 to avoid damage to the MOSFET due to overvoltage. Specifically, if the gate voltage Vg usually exceeds, for example, but not limited to, 40V (depending on the type of the MOSFET), it will cause 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 a level lower than 40V (for example but not limited to 20V) to prevent the gate voltage Vg from being too high and causing damage to the MOSFET.

[0049] The second diode D2 is coupled to the first resistor R1, the first voltage stabilizing unit ZD1, the gate G of the MOSFET, the second voltage stabilizing unit ZD2 and the live terminal 162 of the bus path 16, and when the bus voltage Vbus is less than the stabilizing voltage Vr on the first voltage stabilizing unit ZD1, the second diode D2 is forward biased, so that the stabilizing voltage Vr on the first voltage stabilizing unit ZD1 is released to the bus path 16. At this time, the stabilizing voltage Vr is reduced to be substantially equal to the bus voltage Vbus. Since the stabilizing voltage Vr is substantially equal to the bus voltage Vbus, the energy storage voltage Vs on the energy storage capacitor 24 is reduced along with the reduction of the stabilizing voltage Vr, so as to avoid the voltage difference between the energy storage voltage Vs and the bus voltage Vbus being too large, thereby causing excessive energy to be instantly injected into the bus path 16. Furthermore, since the second-stage conversion unit 14 is usually also a switching power converter, when the input end of the second-stage conversion unit 14 (i.e., on the bus path 16) is lower than the energy storage voltage Vs and does not drop directly to zero, it is prevented that the auxiliary voltage Va continues to release energy to the bus voltage Vbus, causing additional energy to be accumulated at the input end and causing energy waste. Therefore, reducing the regulated voltage Vr to be substantially equal to the bus voltage Vbus can improve the overall efficiency of the conversion system 100. In addition, the second diode D2 can also be coupled to the power output end of the second-stage conversion unit 14 (such as Figure 1 As shown, the positive terminal of the output power Vo) is used to prevent the voltage difference between the energy storage voltage Vs and the output power Vo from being too large, which causes too much energy to be instantly poured into the power output terminal. Its circuit action and function are the same as the second diode D2 coupled to the live wire terminal 162 of the bus path 16, and will not be repeated here. It is worth mentioning that in one embodiment of the present invention, the detailed circuit architecture of the auxiliary power circuit 26 can have a variety of circuits, components, controllers, and even software and hardware implementation methods. Therefore, all circuits, components, controllers, and software and hardware that can achieve the above-mentioned circuit functions should be included in the scope of this embodiment.

[0050] See also Fig. 6A FIG. 1 is a circuit diagram of a first embodiment of a current adjustment unit of the present invention, and is also referred to in conjunction with FIG. Figures 1 to 5 . The current adjustment unit 268 can be a current limiting resistor Rs, one end of the current limiting resistor Rs is coupled to the first resistor R1, and the other end is coupled to the drain D of the metal oxide semi-field effect transistor. The current limiting resistor Rs limits the charging current Ic for charging the energy storage capacitor 24 to avoid the energy storage capacitor 24 from having a large instantaneous current and causing a reduction in life. It is worth mentioning that in one embodiment of the present invention, the current limiting resistor Rs can also be coupled after the charging path 266 or before the voltage stabilizing circuit 264. That is, the current limiting resistor Rs can be coupled on the path from the conversion unit 262 to the energy storage capacitor 24.

[0051] See also Figure 6BFIG. 1 is a circuit diagram of a second embodiment of a current adjustment unit of the present invention, and is also referred to in conjunction with FIG. Figure 1~6A The current adjustment unit 268' of this embodiment is Fig. 6A The difference between the current adjustment unit 268 and the current adjustment unit 268 is that the current adjustment 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 voltage regulator circuit 264, and the base B is coupled to the input terminal X of the thyristor U1 and the voltage regulator circuit 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 metal oxide semiconductor field effect transistor. 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 across the current detection resistor Ri through the output terminal Y and the control terminal Z, and adjusts the current of the input terminal X of the thyristor U1 according to the voltage difference. At this time, since the transistor Qt has the 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 at the same time. Therefore, when the charging current Ic is too large, the voltage difference across the current detection resistor Ri becomes larger, so that the current at the input terminal X of the thyristor U1 is adjusted smaller, thereby reducing the current at the emitter E of the transistor Qt. Moreover, when the charging current Ic becomes smaller, the voltage difference across the current detection resistor Ri becomes smaller, so that the current at the input terminal X of the thyristor U1 is adjusted larger, thereby increasing the current at the emitter E of the transistor Qt. The thyristor U1 controls the transistor Qt to provide a charging current Ic of a fixed current value to charge the energy storage capacitor 24 according to the voltage drop of the current detection resistor Ri. It is worth mentioning that in one embodiment of the present invention, the current adjustment units 268 and 268' are not limited to being composed of only the above-mentioned 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 in combination with a circuit. Therefore, as long as the component or circuit has a current adjustment function, it should be included in the scope of this embodiment. In addition, since the current adjustment unit 268' includes a transistor Qt, a thyristor U1, and a current detection resistor Ri, the function of the charging path 266 can be replaced by the current adjustment unit 268'. That is, the current adjustment unit 268' is the charging path 266, and the current detection resistor Ri in the current adjustment unit 268' is directly coupled to the first end 242 of the energy storage capacitor 24, and the current of Ic is adjusted through the transistor Qt, so that the energy storage capacitor 24 establishes an energy storage voltage Vs. Alternatively, the charging path 266 is a diode component (not shown). The anode of the diode component is coupled to the current detection resistor Ri, and the cathode of the diode component is coupled to the energy storage capacitor 24.

[0052] The above-described embodiments are only preferred embodiments for fully illustrating the present invention, and the protection scope of the present invention is not limited thereto. Equivalent substitutions or changes made by those skilled in the art based on the present invention are within the protection scope of the present invention. The protection scope of the present invention shall be subject to the claims.

Claims

1. A control circuit with extended holding time, characterized in that: A bus path coupled to a conversion circuit, the control circuit comprising: a bypass circuit coupled to a live terminal of the bus path; a storage capacitor, comprising a first end and a second end, the first end being coupled to the bypass circuit, and the second end being coupled to a ground terminal of the bus path; and an auxiliary power circuit, coupling the bypass circuit and the conversion circuit; The auxiliary power supply circuit includes: a conversion unit coupled to the conversion circuit; a voltage stabilizing circuit coupled to the conversion unit, and the voltage stabilizing circuit includes a voltage stabilizing unit; a charging path coupled to the voltage stabilizing circuit, the energy storage capacitor and the bypass circuit; Among them, the auxiliary power supply circuit provides an energy storage voltage to the energy storage capacitor according to an operating 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 maintenance time; the conversion unit converts the operating voltage into an auxiliary voltage, and the voltage stabilizing circuit generates a regulated voltage according to the auxiliary voltage; the regulated voltage turns on the charging path, and the regulated voltage charges the energy storage capacitor through the charging path, so that the energy storage capacitor establishes the energy storage voltage, and the voltage stabilizing unit limits a gate voltage of the charging path to be less than or equal to a rated voltage.

2. The control circuit with extended holding time as claimed in claim 1, characterized in that: The conversion unit is an induction coil, which is coupled to a transformer of the conversion circuit and converts the working voltage of the transformer into the auxiliary voltage by electromagnetic coupling.

3. The control circuit with extended holding time as claimed in claim 1, characterized in that: The conversion unit is a switching power converter. The switching 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.

4. The control circuit with extended holding time as claimed in claim 1, characterized in that: The conversion unit is a linear power converter, which is coupled to the bus path and uses the bus voltage as the working voltage to convert the working voltage into the auxiliary voltage.

5. The control circuit with extended holding time as claimed in claim 1, characterized in that: The conversion circuit includes an AC-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.

6. The control circuit with extended holding time as claimed in claim 1, characterized in that: The conversion circuit includes a DC-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 to convert the working voltage into the auxiliary voltage.

7. The control circuit with extended holding time as claimed in claim 1, characterized in that: 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.

8. The control circuit with extended holding time as claimed in claim 1, characterized in that: The bypass circuit includes: a voltage detection circuit coupled to the bus path; a control unit, coupled to the voltage detection circuit; a switch unit, coupling 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 determines whether to turn on 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.

9. The control circuit with extended holding time as claimed in claim 1, characterized in that: The auxiliary power supply circuit also includes: A current limiting resistor, coupling the voltage stabilizing circuit and the charging path; The current limiting resistor limits a charging current for charging the energy storage capacitor.

10. The control circuit with extended holding time as claimed in claim 1, characterized in that: The auxiliary power supply circuit also includes: a transistor, coupled to the voltage stabilizing circuit; a thyristor unit coupled to 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 to charge the energy storage capacitor according to the voltage drop of the current detection resistor.

11. The control circuit with extended holding time as claimed in claim 10, characterized in that: A current adjustment unit formed by the transistor, the thyristor unit and the current detection resistor is the charging path.

12. The control circuit with extended holding time as claimed in claim 10, characterized in that: The charging path is a diode component.

13. The control circuit with extended holding time as claimed in claim 1, characterized in that: The energy storage voltage is the regulated voltage minus a switch conduction voltage of the charging path.

14. The control circuit with extended holding time as claimed in claim 1, characterized in that: A capacitance withstand voltage of the energy storage capacitor is less than a maximum voltage of the bus voltage.

15. The control circuit with extended holding time as claimed in claim 1, characterized in that: The auxiliary power supply circuit also includes: a second diode, coupling 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.

16. The control circuit with extended holding time as claimed in claim 1, characterized in that: The auxiliary power supply circuit also includes: a second diode, coupling the voltage stabilizing circuit and a power output terminal of the conversion circuit; When an output power source output by the conversion circuit is less than the regulated voltage, the second diode is forward biased, so that the regulated voltage is released to the power output terminal.

17. A conversion system with extended holding time, characterized in that include: A conversion circuit comprising: a first-stage conversion unit, converting an input power source into a bus voltage; and a second-stage conversion unit coupled to the first-stage conversion unit through a bus path and converting the bus voltage into an output power source; and A control circuit is coupled to the bus path and includes: a bypass circuit coupled to a live terminal of the bus path; a storage capacitor, comprising a first end and a second end, the first end being coupled to the bypass circuit, and the second end being coupled to a ground terminal of the bus path; and an auxiliary power circuit, coupling the bypass circuit and the conversion circuit; In which, the auxiliary power supply circuit provides an energy storage voltage to the energy storage capacitor according to an operating 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 maintenance time.

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