Power conversion system capable of limiting input current surge

Abstract

The invention discloses a power conversion system capable of limiting input current surge. The power conversion system is used for converting an input power supply to generate an output power supply, and comprises a current limiting circuit which is used for clamping an input current of the input power supply in a current clamping state so that the input current does not exceed an input current limit value; and the electric quantity adjusting circuit is used for converting the output power supply to generate a temporary storage power supply in the temporary storage capacitor in the charging mode, and converting the temporary storage power supply to generate the output power supply in cooperation with the current limiting circuit in the discharging mode. When the input current reaches the current threshold value, the electric quantity adjusting circuit enters a discharging mode. In the discharging mode, the electric quantity adjusting circuit is used for adjusting the output voltage of the output power supply to a target level, and the target level is lower than the input voltage of the input power supply.

Description

Technical Field

[0001] The invention relates to a power conversion system, and more particularly to a power conversion system capable of limiting input current surges. Background Art

[0002] Prior cases related to the present application include: “Power supply and power supplying method with power backup” (US10892637B2).

[0003] Figure 1 A power conversion system of the prior art is shown. Figure 1 As shown, the power conversion system 900 is used to convert the input power PS to generate the output power VB, wherein the input current Iin related to the input power PS flows through the switch 90. In the power conversion system 900 of the prior art, the comparator 91 is used to compare the sensing signal Ics related to the input current Iin with the current threshold Ith1, and the comparator 92 is used to compare the feedback signal Vfb related to the output power VB with the voltage threshold Vth. In the charging mode, that is, when the sensing signal Ics is lower than the current threshold Ith1 and / or the feedback signal Vfb is higher than the voltage threshold Vth, the switching converter 95 converts the output power VB to generate a power stored in the capacitor C. In the discharge mode, that is, when the sensing signal Ics is higher than the current threshold Ith1 and the feedback signal Vfb is lower than the voltage threshold Vth, the AND gate 93 controls the switching converter 95 through the pulse width modulation control circuit 94 according to the comparison results of the comparator 91 and the comparator 92, so as to release the energy stored in the capacitor C to provide it to the output power supply VB, thereby compensating for the short-term shortage of the input power supply PS to maintain the voltage and / or current of the output power supply VB from being too low.

[0004] The disadvantage of the above-mentioned prior art is that since the power conversion system 900 controls the switching converter 95 to operate in the charging mode or the discharging mode through the AND gate 93, that is, it is necessary to enter the discharging mode only when the sensing signal Ics is higher than the current threshold Ith1 and the feedback signal Vfb is lower than the voltage threshold Vth. Therefore, when the output power VB drops to a certain level, the power conversion system 900 will be repeatedly switched between the charging mode and the discharging mode, thereby causing a large oscillation of the input current Iin, thereby causing system instability.

[0005] In view of this, the present invention aims at the above-mentioned deficiencies of the prior art and proposes a power conversion system capable of limiting input current surges. By adjusting the output voltage, the input current can be maintained in a clamped state, thereby enabling the power conversion system to stably operate in a discharge mode, thereby achieving the advantages of limiting input current surges and stabilizing the power conversion system. Summary of the invention

[0006] In one aspect, the present invention provides a power conversion system for converting an input power supply to generate an output power supply, comprising: a current limiting circuit for clamping an input current of the input power supply so that it does not exceed an input current limit in a current clamping state; and a power regulation circuit for converting the output power supply to generate a temporary power supply in a temporary storage capacitor in a charging mode, and for converting the temporary power supply in a discharge mode to cooperate with the current limiting circuit to generate the output power supply, wherein the power regulation circuit enters the discharge mode when the input current reaches a current threshold; wherein in the discharge mode, the power regulation circuit is used to regulate an output voltage of the output power supply to a target level, wherein the target level is lower than an input voltage of the input power supply.

[0007] In a preferred embodiment, the target level is lower than the input voltage to a degree such that the current limiting circuit is maintained in the current clamping state.

[0008] In a preferred embodiment, the current limiting circuit includes a path switch, wherein a preset difference between the input voltage and the target level is greater than the product of the input current limit and an on-resistance value when the path switch is controlled to be on, so that the current limiting circuit is maintained in the current clamping state.

[0009] In a preferred embodiment, the on-resistance value is the maximum resistance value of the path switch when it is controlled to be on under all operating conditions and all process variations.

[0010] In a preferred embodiment, the condition for entering the discharge mode does not include the level of the output voltage.

[0011] In a preferred embodiment, the power regulation circuit is a switching converter, including an inductor and at least one switch, for performing conversion between the output power and the temporary power.

[0012] In a preferred embodiment, the switching converter also includes an error amplifier circuit for generating an error amplification signal based on a reference voltage and the output voltage, thereby controlling the at least one switch to perform conversion between the output power supply and the temporary power supply, wherein in the discharge mode, the reference voltage is related to the target level.

[0013] In a preferred embodiment, the current limiting circuit further includes a current control circuit for sensing the input current and controlling the path switch to clamp the input current so that the input current does not exceed the input current limit according to a difference between the input current and a reference signal.

[0014] In a preferred embodiment, the current threshold is greater than the input current limit.

[0015] The following is a detailed description through specific embodiments to make it easier to understand the purpose, technical content, characteristics and effects achieved by the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A prior art power conversion system is shown.

[0017] Figure 2A A block diagram showing an embodiment of a power conversion system of the present invention is shown.

[0018] Figure 2B An operating waveform diagram of a power conversion system according to an embodiment of the present invention is shown.

[0019] Figure 3 A block diagram showing an embodiment of a power conversion system of the present invention is shown.

[0020] Figure 4 A block diagram showing an embodiment of a power conversion system of the present invention is shown.

[0021] Figure 5 A schematic diagram showing a specific embodiment of the power conversion system of the present invention.

[0022] Figure 6 A schematic diagram showing a specific embodiment of the power conversion system of the present invention.

[0023] Explanation of symbols in the figure

[0024] 100, 103, 104, 105: Current limiting circuit

[0025] 1002, 1003, 1004, 1005, 1006: Power conversion system

[0026] 130, 135: Path switch

[0027] 150, 155: Current control circuit

[0028] 200, 203, 205, 206: Power regulation circuit

[0029] 236: Error amplifier circuit

[0030] 250: Modulation control circuit

[0031] 300: Comparator

[0032] 500: Load

[0033] 90: Switch

[0034] 900: Power conversion system

[0035] 91, 92: Comparator

[0036] 93: AND gate

[0037] 94: Pulse Width Modulation Control Circuit

[0038] 95: Switching converter

[0039] C: Capacitor

[0040] Cap: Temporary Capacitor

[0041] Ea: Error amplification signal

[0042] EN: Enable signal

[0043] Ics: sensing signal

[0044] Ict: Temporary output current

[0045] Id: Current difference

[0046] Iin: input current

[0047] IL: Inductor current

[0048] Ild: output current

[0049] Ilim: Input current limit

[0050] Ith, Ith1: Current threshold

[0051] L: Inductor

[0052] M1, M2: transistors

[0053] PS: Input power

[0054] Sc1, Sc2: Switching control signal

[0055] Scp: path control signal

[0056] SW1, SW2: switches

[0057] t1, t2: time point

[0058] VB: output power

[0059] Vcap: Temporary storage voltage

[0060] Vct: Temporary output voltage

[0061] Vd: preset difference

[0062] Vfb: feedback signal

[0063] VIin: sensing signal

[0064] VIlim: reference signal

[0065] Vin: input voltage

[0066] VIth: Threshold voltage

[0067] Vref: reference voltage

[0068] Vsrc: output voltage

[0069] Vtarg: target level

[0070] Vth: voltage threshold DETAILED DESCRIPTION

[0071] The drawings in the present invention are all schematic, and are mainly intended to show the coupling relationship between various circuits and the relationship between various signal waveforms. The circuits, signal waveforms and frequencies are not drawn according to scale.

[0072] Figure 2A A block diagram of an embodiment of the power conversion system of the present invention is shown. In one embodiment, the power conversion system 1002 is used to convert input power to generate output power to the load 500, wherein the input power includes an input current Iin and an input voltage Vin, and the output power includes an output current Ild and an output voltage Vsrc. In one embodiment, the power conversion system 1002 includes: a current limiting circuit 100 and a power regulation circuit 200.

[0073] In one embodiment, the current limiting circuit 100 is used to clamp the input current Iin so that it does not exceed the input current limit Ilim in the current clamping state. In one embodiment, the power regulating circuit 200 is used to convert the output power to generate a temporary power in the temporary capacitor Cap in the charging mode, and to convert the temporary power to cooperate with the current limiting circuit 100 to generate the output power in the discharge mode. Specifically, in this embodiment, the power regulating circuit 200 is used to convert the output voltage Vsrc to generate a temporary voltage Vcap in the temporary capacitor Cap in the charging mode, and to convert the temporary voltage Vcap to cooperate with the current limiting circuit 100 to generate the output voltage Vsrc in the discharge mode.

[0074] Please also see Figure 2A and Figure 2B , Figure 2B The operation waveform diagram of an embodiment of the power conversion system of the present invention is shown. In one embodiment, when the input current Iin reaches the current threshold Ith, the power regulation circuit 200 Figure 2BAt time t1, the discharge mode is entered. At this time, the power regulation circuit 200 converts the temporary voltage Vcap to generate a temporary output power supply to cooperate with the current limiting circuit 100 to generate the output voltage Vsrc. From one point of view, in the discharge mode, the output power supply is the superposition of the input power supply and the temporary output power supply. Specifically, the output current Ild is the superposition of the input current Iin and the temporary output current Ict, wherein the temporary output power supply includes the temporary output current Ict and the temporary output voltage Vct. In this embodiment, the temporary output voltage Vct corresponds to the output voltage Vsrc. In one embodiment, in the discharge mode, the power regulation circuit 200 is used to adjust the output voltage Vsrc to the target level Vtarg (such as Figure 2B As shown by the short dashed line in the middle, the current limiting circuit 100 clamps the input current Iin so that it does not exceed the input current limit Ilim.

[0075] It should be noted that, in one embodiment, the target level Vtarg is lower than the level of the input voltage Vin. In a specific embodiment, the target level Vtarg is lower than the input voltage Vin to a certain extent (e.g., lower than a predetermined difference Vd), so that the current limiting circuit 100 is maintained in a current clamping state. It should also be noted that, in one embodiment, the current threshold Ith is greater than the input current limit Ilim, so that when the output current Ild is greater than the current threshold Ith, the current limiting circuit 100 can operate more stably in the clamping mode. The above operation details are described in detail later.

[0076] Figure 3 A block diagram of an embodiment of the power conversion system of the present invention is shown. Figure 3 In the power conversion system 1003, the current limiting circuit 103 includes a path switch 130, and the power regulation circuit 203 is configured as a switching converter. In one embodiment, the power regulation circuit 203 includes an inductor L and at least one switch SW1 for converting between an output power source (e.g., an output voltage Vsrc) and a temporary power source (e.g., a temporary voltage Vcap).

[0077] Figure 4 A block diagram showing an embodiment of a power conversion system of the present invention is shown. Figure 4 The power conversion system 1004 is similar to Figure 3 The power conversion system 1003, in one embodiment, Figure 4 The current limiting circuit 104 further includes a current control circuit 150 for sensing the input current Iin and generating a path control signal Scp according to a difference between the input current Iin and a reference signal to control the path switch 130 to clamp the input current Iin so that it does not exceed the input current limit Ilim.

[0078] Figure 5A schematic diagram showing a specific embodiment of the power conversion system of the present invention. Figure 5 The power conversion system 1005 corresponds to Figure 4 In one embodiment, the power conversion system 1004 is configured as follows. Figure 5 As shown, the path switch 135 is configured as two metal oxide semiconductor (MOS) transistors M1 and M2 coupled in series, and the body electrodes of the MOS transistors M1 and M2 are reversely connected to prevent the body diodes from being turned on. In a specific embodiment, the current control circuit 155 in the current limiting circuit 105 is configured as an error amplifier circuit, which is used to generate a path control signal Scp according to the difference between the sensing signal VIin related to the input current Iin and the reference signal VIlim to control the gate of the path switch 135, thereby clamping the input current Iin so that it does not exceed the input current limit Ilim. In this embodiment, the reference signal VIlim is related to the input current limit Ilim.

[0079] In a specific embodiment, if Figure 5 As shown, the power regulation circuit 205 is configured as a switching converter, including an inductor L, a switch SW1 and a switch SW2. In one embodiment, in the charging mode, the power regulation circuit 205 is used as a boost converter, and the inductor L is periodically switched by the switch SW1 and the switch SW2 to convert the output voltage Vsrc to generate a temporary voltage Vcap in the temporary capacitor Cap. In other words, in the charging mode, the power regulation circuit 205 is used to boost the output voltage Vsrc to charge the capacitor Cap. In one embodiment, in the discharging mode, the power regulation circuit 205 is used as a buck converter, and the inductor L is periodically switched by the switch SW1 and the switch SW2 to convert the temporary voltage Vcap and cooperate with the current limiting circuit 105 to generate the output voltage Vsrc. In other words, in the discharging mode, the power regulation circuit 205 is used to buck the temporary voltage Vcap stored in the capacitor Cap to discharge the capacitor Cap. In the charging mode or in the discharging mode, the temporary voltage Vcap is greater than or equal to the output voltage Vsrc.

[0080] Figure 6 A schematic diagram showing a specific embodiment of the power conversion system of the present invention. Figure 6 The power conversion system 1006 is similar to Figure 5 The power conversion system 1005, in one embodiment, Figure 6The power regulation circuit 206 (i.e., the switching converter) further includes an error amplifier circuit 236 and a modulation control circuit 250. In a specific embodiment, the error amplifier circuit 236 is used to generate an error amplification signal Ea according to the difference between a reference voltage Vref and a signal related to the output voltage Vsrc, and the modulation control circuit 250 is used to generate switching control signals Sc1 and Sc2 according to the error amplification signal Ea to control the switch SW1 and the switch SW2 respectively, so as to convert between the output power supply (such as the output voltage Vsrc) and the temporary power supply (such as the temporary voltage Vcap). In one embodiment, the modulation control circuit 250 generates the switching control signals Sc1 and Sc2 in a pulse width modulation manner according to the error amplification signal Ea. In the discharge mode, the reference voltage Vref is related to the target level Vtarg. In this embodiment, in the discharge mode, the reference voltage Vref is equal to the target level Vtarg, and the signal related to the output voltage Vsrc is the output voltage Vsrc itself.

[0081] In a specific embodiment, if Figure 6 As shown, the power conversion system 1006 further includes a comparator 300 for comparing the sensing signal VIin with the threshold voltage VIth to generate an enable signal EN. The enable signal EN is used to indicate that when the level of the sensing signal VIin is higher than the level of the threshold voltage VIth, the modulation control circuit 250 controls the switch SW1 and the switch SW2 to enter a discharge mode to discharge the capacitor Cap. In one embodiment, the sensing signal VIin is related to the input current Iin, and the threshold voltage VIth is related to the current threshold Ith.

[0082] Please also see Figure 6 and Figure 2B In one embodiment, Figure 2B Before the time point t1, the power regulation circuit 206 operates in the charging mode, and the level of the inductor current IL is positive. In one embodiment, when the level of the sensing signal VIin is higher than the level of the threshold voltage VIth, the input current Iin (eg Figure 2B The level of the second waveform (shown by the solid line) is higher than the level of the current threshold Ith. Figure 2B At the time point t1 shown, the power regulation circuit 206 enters the discharge mode, and the current limiting circuit 105 enters the current clamping state. In the discharge mode from the time point t1 to the time point t2, the level of the inductor current IL is a negative value, wherein the inductor current IL corresponds to the aforementioned temporary output current Ict (inversely related to each other). On the other hand, the input current Iin is continuously clamped at not exceeding the input current limit Ilim. Therefore, in the discharge mode from the time point t1 to the time point t2, the output current Ild is the superposition of the absolute value of the input current Iin and the inductor current IL. In addition, the level of the temporary voltage Vcap gradually decreases in the discharge mode.

[0083] In one embodiment, when the output current Ild is lower than the input current limit Ilim again, Figure 2B At time t2, the power regulation circuit 206 returns to the charging mode. It should be noted that the above conditions for entering the discharge mode or the charging mode do not include the level of the output voltage Vsrc.

[0084] In one embodiment, the current threshold Ith is greater than the input current limit Ilim, and the current threshold Ith and the input current limit Ilim have a current difference Id, wherein the current difference Id is large enough to ensure that when the level of the input current Iin is higher than the level of the current threshold Ith and enters the discharge mode, the input current Iin can be continuously clamped at not exceeding the input current limit Ilim, so as to avoid the surge of the input current Iin causing the power regulation circuit 206 to continuously switch between the charging mode and the discharging mode. Therefore, in the power conversion system of the present invention, when the output current Ild is greater than the current threshold Ith, the current limiting circuit 100 can operate more stably in the clamping mode.

[0085] In one embodiment, Figure 2B In the discharge mode from time point t1 to time point t2, the power regulation circuit 206 regulates the output voltage Vsrc to the target level Vtarg through the error amplifier circuit 236, and the preset difference Vd between the input voltage Vin and the target level Vtarg is greater than the product of the input current limit Ilim and the on-resistance value when the path switch 135 is controlled to be on, so that the current limiting circuit 105 is maintained in the current clamping state. In other words, in this embodiment, the product of the input current limit value Ilim and the on-resistance value when the path switch 135 is controlled to be on is the drain-source voltage of the path switch 135, and the preset difference Vd between the input voltage Vin and the target level Vtarg is the target drain-source voltage of the path switch 135 to be adjusted. From another point of view, the current limiting circuit 100 is equivalent to limiting the drain-source voltage of the path switch 135 to be not greater than its target drain-source voltage, that is, the drain-source voltage of the path switch 135 is clamped at the target drain-source voltage, thereby causing the input current Iin to be clamped at no more than the input current limit value Ilim.

[0086] It should be noted that the above-mentioned on-resistance value is the maximum of the resistance values ​​of the path switch 135 when it is controlled to be on under all operating conditions and all process variations, so as to ensure that the preset difference Vd between the input voltage Vin and the target level Vtarg is greater than the product of the input current limit Ilim and the on-resistance value of the path switch 135 when it is controlled to be on.

[0087] The present invention has been described above with respect to the preferred embodiment, but the above is only to make it easy for those skilled in the art to understand the content of the present invention, and is not used to limit the scope of rights of the present invention. The various embodiments described are not limited to individual applications, but can also be used in combination. For example, two or more embodiments can be used in combination, and part of the components in one embodiment can also be used to replace the corresponding components in another embodiment. In addition, under the same spirit of the present invention, those skilled in the art can think of various equivalent changes and various combinations. For example, the present invention refers to "processing or calculating or generating an output result according to a certain signal", which is not limited to the signal itself, but also includes, when necessary, converting the signal to voltage and current, current and voltage, and / or ratio conversion, and then processing or calculating according to the converted signal to generate an output result. It can be seen from this that under the same spirit of the present invention, those skilled in the art can think of various equivalent changes and various combinations, and there are many combinations, which are not listed one by one here. Therefore, the scope of the present invention should cover the above and all other equivalent changes.

Claims

1. A power conversion system for converting an input power source to generate an output power source, comprising: a current limiting circuit, used for clamping an input current of the input power source so that the input current does not exceed an input current limit value in a current clamping state; and a power regulating circuit, used for converting the output power to generate a temporary power in a temporary capacitor in a charging mode, and for converting the temporary power to cooperate with the current limiting circuit to generate the output power in a discharging mode, wherein the power regulating circuit enters the discharging mode when the input current reaches a current threshold; In the discharge mode, the power regulation circuit is used to regulate an output voltage of the output power source to a target level, wherein the target level is lower than an input voltage of the input power source.

2. The power conversion system according to claim 1, wherein: The target level is lower than the input voltage to a certain extent so that the current limiting circuit is maintained in the current clamping state.

3. The power conversion system according to claim 2, wherein: The current limiting circuit includes a path switch, wherein a preset difference between the input voltage and the target level is greater than the product of the input current limit and an on-resistance value when the path switch is controlled to be on, so that the current limiting circuit is maintained in the current clamping state.

4. The power conversion system according to claim 2, wherein: The on-resistance value is the maximum resistance value of the path switch when it is controlled to be on under all operating conditions and all process variations.

5. The power conversion system according to claim 1, wherein: The condition for entering the discharge mode does not include depending on the level of the output voltage.

6. The power conversion system according to claim 3, wherein: The power regulation circuit is a switching converter, including an inductor and at least one switch, for converting between the output power and the temporary power.

7. The power conversion system according to claim 6, wherein: The switching converter further includes an error amplifier circuit for generating an error amplifier signal according to a reference voltage and the output voltage, thereby controlling the at least one switch to perform conversion between the output power source and the temporary power source, wherein in the discharge mode, the reference voltage is related to the target level.

8. The power conversion system according to claim 3, wherein: The current limiting circuit further includes a current control circuit for sensing the input current and controlling the path switch to clamp the input current so that the input current does not exceed the input current limit value according to the difference between the input current and a reference signal.

9. The power conversion system according to claim 1, wherein: The current threshold is greater than the input current limit.

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