Auxiliary power supply under-voltage shutdown circuit

Abstract

The utility model provides an auxiliary power supply under-voltage shutdown circuit. The auxiliary power supply under-voltage shutdown circuit comprises a voltage acquisition circuit, a switch tube Q3 and a switch tube Q1, the voltage acquisition circuit is used for detecting the input voltage of an auxiliary power supply, the output end of the voltage acquisition circuit is connected to the control end of the switch tube Q3, the first end of the switch tube Q3 is connected with a first power supply, and the second end of the switch tube Q3 is connected with a second power supply. The first end of the switch tube Q3 is grounded through a resistor R18, the second end of the switch tube Q3 is grounded through a resistor R18, the second end of the switch tube Q3 is connected to the control end of the switch tube Q1, the first end of the switch tube Q1 is grounded, the second end of the switch tube Q1 is connected to the feedback end of the driving module, the output end of the driving module is connected to the control end of the switch tube Q2, and the switch tube Q2 is a power element of an auxiliary power supply. The problem that the battery cannot be normally charged after the mains supply is recovered due to overlong mains supply recovery time can be solved.

Description

Technical Field

[0001] This disclosure relates to the field of power supply technology, and in particular to an auxiliary power supply undervoltage shutdown circuit. Background Technology

[0002] In UPS modules and energy storage modules, the auxiliary power supply mostly adopts a flyback topology and draws power from both the AC mains side and the DC battery side to ensure that the module can still operate normally after either the AC or DC power is lost.

[0003] This power supply method can meet the application scenarios of most UPS systems. However, when the UPS system loses power to the mains and the bypass, the system switches to battery power. When the battery voltage drops to the EOD voltage value, the UPS system switches from normal operation to standby mode. After the mains power is restored, it continues to supply power to the load and charge the battery. If the conditions for restoring the mains power are not available on site in a short time, the auxiliary power supply of the module itself has a wide operating voltage range due to the use of flyback topology. When the battery voltage is lower than the EOD voltage, the auxiliary power supply itself can still work normally. At this time, because the module still needs the battery to provide energy when in standby mode, the standby time is too long and the battery will discharge to an extremely low value and cannot be charged normally after the mains power is restored. Utility Model Content

[0004] This disclosure provides an auxiliary power undervoltage shutdown circuit to solve the problem that the battery cannot be charged normally after the mains power is restored due to the long mains power recovery time.

[0005] This disclosure provides an auxiliary power supply undervoltage shutdown circuit, including a voltage acquisition circuit, a switching transistor Q3, and a switching transistor Q1.

[0006] The voltage acquisition circuit is used to detect the input voltage of the auxiliary power supply. The output terminal of the voltage acquisition circuit is connected to the control terminal of the switching transistor Q3. The first terminal of the switching transistor Q3 is connected to the first power supply, and the second terminal of the switching transistor Q3 is grounded through resistor R18.

[0007] The second terminal of the switch Q3 is connected to the control terminal of the switch Q1, the first terminal of the switch Q1 is grounded, the second terminal of the switch Q1 is connected to the feedback terminal of the drive module, the output terminal of the drive module is connected to the control terminal of the switch Q2, and the switch Q2 is a power element of the auxiliary power supply.

[0008] In one exemplary embodiment of this disclosure, the first power supply is provided by the reference voltage terminal of the drive module.

[0009] In an example embodiment of the present disclosure, the auxiliary power supply under-voltage shutdown circuit further comprises an overcurrent detection circuit, the overcurrent detection circuit comprises a sampling resistor R15, a first end of the sampling resistor R15 is connected with a first end of the switch tube Q2, a second end of the sampling resistor R15 is grounded, and the first end of the sampling resistor R15 is connected with a current feedback end of the driving module.

[0010] In an example embodiment of the present disclosure, the auxiliary power supply under-voltage shutdown circuit further comprises a switch tube Q4, a resistor R19 and a voltage stabilizing tube Z1,

[0011] a first end of the resistor R19 is connected with a second power supply, a second end of the resistor R19 is connected with a cathode of the voltage stabilizing tube Z1, and an anode of the voltage stabilizing tube Z1 is grounded,

[0012] a first end of the switch tube Q4 is connected with the second power supply, a second end of the switch tube Q4 is connected with a power supply end of the driving module, and a control end of the switch tube Q4 is connected with the cathode of the voltage stabilizing tube Z1.

[0013] In an example embodiment of the present disclosure, the voltage collection circuit of the auxiliary power supply under-voltage shutdown circuit comprises resistors R4, R3, R2, R6 and R17 connected in series,

[0014] the resistor R4 is further connected with an input voltage of the auxiliary power supply, the resistor R17 is grounded, and a connection point of the resistor R6 and the resistor R17 is an output end of the voltage collection circuit.

[0015] In an example embodiment of the present disclosure, the auxiliary power supply comprises a transformer, a first end of an output coil of the transformer is connected with an anode of a diode D2A, a cathode of the diode D2A is connected with a first end of a filter capacitor, a second end of the filter capacitor is connected with a second end of the output coil of the transformer, the second end of the output coil of the transformer is grounded, and the diode D2A is connected in parallel with a diode D2B.

[0016] In an example embodiment of the present disclosure, the auxiliary power supply under-voltage shutdown circuit further comprises a capacitor C3 and resistors R10 and R11, a first end of the capacitor C3 is connected with the anode of the diode D2A, the first end of the capacitor C3 is connected with a first end of the resistor R10, a second end of the resistor R10 is connected with the cathode of the diode D2A, and the resistor R11 is connected in parallel with the resistor R10.

[0017] The auxiliary power supply under-voltage shutdown circuit provided by the example embodiments of the present disclosure has the following working principles and beneficial effects:

[0018] When the input voltage of the auxiliary power supply is normal (higher than the set value), the output voltage of the voltage acquisition circuit makes the switch tube Q3 cut off, the control end of the switch tube Q1 is connected to the ground through the resistor R18, the switch tube Q1 cuts off, at this time, the feedback end of the driving module is not affected by the switch tube Q1, the driving module can work normally, the driving module outputs the PWM control signal to the control end of the switch tube Q2, and the auxiliary power supply works normally.

[0019] When the input voltage of the auxiliary power supply is too low (lower than the set value), the output voltage of the voltage acquisition circuit makes the switch tube Q3 conduct, the control end of the switch tube Q1 is connected to the first power supply, the switch tube Q1 conducts, at this time, the feedback end of the driving module is connected to the ground, the driving module stops outputting the PWM control signal to the control end of the switch tube Q2, and the auxiliary power supply shuts down.

[0020] The auxiliary power supply under-voltage shutdown is realized, and the battery is prevented from being discharged to a very low value and being unable to be normally charged after the mains power is restored. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present disclosure, and other drawings can be obtained by those skilled in the art without creative labor.

[0022] Figure 1 It is a schematic diagram of the auxiliary power supply under-voltage shutdown circuit provided by the embodiments of the present disclosure. DETAILED DESCRIPTION

[0023] In order to make the personnel in the technical field better understand the present scheme, the technical solutions in the embodiments of the present scheme will be clearly described below in combination with the drawings in the embodiments of the present scheme. Obviously, the described embodiments are only some of the embodiments of the present scheme, not all. Based on the embodiments in the present scheme, all other embodiments obtained by those skilled in the art without creative labor should be within the scope of protection of the present scheme.

[0024] The term "comprising" and other any variations thereof in the specification and claims of the present scheme and the above-mentioned drawings means "including but not limited to", and is intended to cover non-exclusive inclusion, and is not limited to the examples listed in the text. In addition, the terms "first" and "second" are used to distinguish different objects, not to describe a specific order.

[0025] The implementation of the present disclosure will be described in detail below in combination with specific drawings:

[0026] Figure 1 A schematic diagram of an auxiliary power supply under-voltage shutdown circuit is provided for the embodiments of the present disclosure. Referring to Figure 1 The auxiliary power supply under-voltage shutdown circuit comprises a voltage acquisition circuit, a switching tube Q3 and a switching tube Q1,

[0027] The voltage acquisition circuit is used to detect the input voltage of the auxiliary power supply, the output end of the voltage acquisition circuit is connected to the control end of the switching tube Q3, the first end of the switching tube Q3 is connected to the first power supply, and the second end of the switching tube Q3 is connected to the ground through the resistor R18,

[0028] The second end of the switching tube Q3 is connected to the control end of the switching tube Q1, the first end of the switching tube Q1 is connected to the ground, and the second end of the switching tube Q1 is connected to the feedback end of the driving module, the output end of the driving module is connected to the control end of the switching tube Q2, and the switching tube Q2 is a power element of the auxiliary power supply.

[0029] In the present embodiment, the switching tube Q3 can be selected as a PNP triode, and the switching tube Q1 can be selected as an NPN triode. When the input voltage of the auxiliary power supply is normal (higher than the set value), the output end voltage of the voltage acquisition circuit makes the switching tube Q3 cut off, the control end (base) of the switching tube Q1 is connected to the ground through the resistor R18, the switching tube Q1 cuts off, the feedback end of the driving module U1 is not affected by the switching tube Q1 at this time, the driving module U1 can work normally, the driving module U1 outputs the PWM control signal to the control end of the switching tube Q2, and the auxiliary power supply works normally.

[0030] When the input voltage of the auxiliary power supply is too low (lower than the set value), the output end voltage of the voltage acquisition circuit makes the switching tube Q3 conduct, the control end (base) of the switching tube Q1 is connected to the first power supply, the switching tube Q1 conducts, the feedback end of the driving module U1 is connected to the ground at this time, the driving module U1 stops outputting the PWM control signal to the control end of the switching tube Q2, and the auxiliary power supply shuts down.

[0031] The present embodiment realizes the under-voltage shutdown of the auxiliary power supply, and avoids that the battery is discharged to a very low value due to the too long standby time, and cannot be normally charged after the mains recovers.

[0032] In an embodiment of the present disclosure, the first power supply is provided by the reference voltage end of the driving module.

[0033] In the present embodiment, the driving module specifically adopts UC2845, the reference voltage end VF of which can output a 5V output voltage, and the reference voltage end VF of the driving module is used as the first power supply, so that the existing module function of the auxiliary power supply can be fully utilized, and no additional power supply is needed.

[0034] As can be seen from the above, the present embodiment only uses a simple resistor and triode to match the peripheral circuit of the driving module UC2845, and realizes the under-voltage shutdown function of the auxiliary power supply.

[0035] In an embodiment of the present disclosure, the auxiliary power supply under-voltage shutdown circuit further comprises an overcurrent detection circuit, the overcurrent detection circuit comprises a sampling resistor R15, a first end of the sampling resistor R15 is connected with a first end of the switch tube Q2, a second end of the sampling resistor R15 is grounded, and the first end of the sampling resistor R15 is connected to a current feedback end of the driving module.

[0036] In the embodiment, the switch tube Q2 is specifically an NMOS tube, the sampling resistor R15 is connected in series with the first end (source) of the switch tube Q2, the current of the switch tube Q2 can be obtained by detecting the voltage division of the sampling resistor R15 (that is, the voltage of the first end of the sampling resistor R15), and the first end of the sampling resistor R15 is connected to the current feedback end of the driving module U1. When the current of the switch tube Q2 is too large, the current feedback end of the driving module U1 obtains a too large voltage signal, the output end OCOM of the driving module U1 stops outputting, and the auxiliary power supply is timely turned off.

[0037] In an embodiment of the present disclosure, the auxiliary power supply under-voltage shutdown circuit further comprises a switch tube Q4, a resistor R19 and a voltage stabilizing tube Z1,

[0038] A first end of the resistor R19 is connected with the second power supply, a second end of the resistor R19 is connected with a cathode of the voltage stabilizing tube Z1, and an anode of the voltage stabilizing tube Z1 is grounded,

[0039] A first end of the switch tube Q4 is connected with the second power supply, a second end of the switch tube Q4 is connected to a power supply end of the driving module, and a control end of the switch tube Q4 is connected with the cathode of the voltage stabilizing tube Z1.

[0040] In the embodiment, a bootstrap circuit is arranged in the driving module U1, when the power is just turned on, the input voltage Vin of the auxiliary power supply provides power for the driving module through the resistor R5, the resistor R8 and the resistor R13, and after the bootstrap is completed, the output end of the auxiliary power supply provides the second power supply +24V for the driving module U1.

[0041] The switch tube Q4 is arranged between the second power supply +24V and the power supply end of the driving module U1, when the second power supply +24V normally outputs, the voltage stabilizing tube Z1 provides a stable conduction voltage for the switch tube Q4, and the stable work of the switch tube Q4 is ensured.

[0042] In an embodiment of the present disclosure, the voltage collection circuit comprises resistors R4, R3, R2, R6 and R17 connected in series,

[0043] The resistor R4 is further connected with the input voltage of the auxiliary power supply, the resistor R17 is grounded, and a connection point of the resistor R6 and the resistor R17 is an output end of the voltage collection circuit.

[0044] In the embodiment, the resistor R4, the resistor R3, the resistor R2, the resistor R6 and the resistor R17 constitute a series voltage dividing circuit, and the terminal voltage of the resistor R17 is the output voltage of the voltage collecting circuit. According to actual needs, the threshold of the under-voltage action can be adjusted by adjusting the resistance values of the resistor R4, the resistor R3, the resistor R2, the resistor R6 and the resistor R17. In the embodiment, the switch tube Q3 and the switch tube Q1 are both silicon-based triodes, and the PN junction conduction voltage drop is 0.7V, and the under-voltage value can be calculated by the following formula:

[0045] .

[0046] In an embodiment of the present disclosure, the auxiliary power supply includes a transformer, a first end of an output coil of the transformer is connected with an anode of a diode D2A, a cathode of the diode D2A is connected with a first end of a filter capacitor, a second end of the filter capacitor is connected with a second end of the output coil of the transformer, the second end of the output coil of the transformer is grounded, and the diode D2A is connected in parallel with a diode D2B.

[0047] In the embodiment, the auxiliary power supply adopts a flyback switching power supply circuit, a diode D2A is arranged on one side of an output coil of a transformer, and the diode D2A plays a role of one-way cut-off, and a diode D2B is arranged in parallel with the diode D2A, so that the current passing capacity can be improved.

[0048] In an embodiment of the present disclosure, the under-voltage shutdown circuit of the auxiliary power supply further includes a capacitor C3 and resistors R10 and R11, a first end of the capacitor C3 is connected with an anode of the diode D2A, the first end of the capacitor C3 is connected with a first end of the resistor R10, a second end of the resistor R10 is connected with a cathode of the diode D2A, and the resistor R11 is connected in parallel with the resistor R10.

[0049] In the embodiment, the capacitor C3 and the resistors R10 and R11 provide a freewheeling circuit for the output coil of the transformer during the cut-off of the diode D2A and the diode D2B, so that an excessively high counter electromotive force is avoided.

[0050] The above embodiments are only used to illustrate the technical solutions of the present disclosure, rather than limit them; although the foregoing embodiments of the present disclosure are described in detail, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features can be replaced equivalently; and the modification or replacement does not make the essence of the corresponding technical solution deviate from the spirit and scope of the technical solutions of the embodiments of the present disclosure.

Claims

1. An auxiliary power supply undervoltage shutdown circuit, comprising: The voltage acquisition circuit, the switching tube Q3 and the switching tube Q1, The voltage acquisition circuit is used for detecting the input voltage of the auxiliary power supply, the output end of the voltage acquisition circuit is connected to the control end of the switching tube Q3, the first end of the switching tube Q3 is connected to the first power supply, and the second end of the switching tube Q3 is connected to the ground through the resistor R18. The second end of the switching tube Q3 is connected to the control end of the switching tube Q1, the first end of the switching tube Q1 is connected to the ground, the second end of the switching tube Q1 is connected to the feedback end of the driving module, the output end of the driving module is connected to the control end of the switching tube Q2, and the switching tube Q2 is a power element of the auxiliary power supply.

2. The auxiliary power supply brown-out shutdown circuit of claim 1, wherein, The first power supply is provided by the reference voltage end of the driving module.

3. The auxiliary power supply brown-out shutdown circuit of claim 1, wherein, The overcurrent detection circuit further includes a sampling resistor R15, the first end of the sampling resistor R15 is connected to the first end of the switching tube Q2, the second end of the sampling resistor R15 is connected to the ground, and the first end of the sampling resistor R15 is connected to the current feedback end of the driving module.

4. The auxiliary power supply brown-out shutdown circuit of claim 1, wherein, The switching tube Q4, the resistor R19 and the voltage stabilizing tube Z1 are further included, The first end of the resistor R19 is connected to the second power supply, the second end of the resistor R19 is connected to the cathode of the voltage stabilizing tube Z1, and the anode of the voltage stabilizing tube Z1 is connected to the ground. The first end of the switching tube Q4 is connected to the second power supply, the second end of the switching tube Q4 is connected to the power supply end of the driving module, and the control end of the switching tube Q4 is connected to the cathode of the voltage stabilizing tube Z1.

5. The auxiliary power supply brown-out shutdown circuit of claim 1, wherein, The voltage acquisition circuit includes the resistor R4, the resistor R3, the resistor R2, the resistor R6 and the resistor R17 connected in series, The resistor R4 is further connected to the input voltage of the auxiliary power supply, the resistor R17 is connected to the ground, and the connection point of the resistor R6 and the resistor R17 is the output end of the voltage acquisition circuit.

6. The auxiliary power supply brown-out shutdown circuit of claim 1, wherein, The auxiliary power supply includes a transformer, the first end of the output coil of the transformer is connected to the anode of the diode D2A, the cathode of the diode D2A is connected to the first end of the filter capacitor, the second end of the filter capacitor is connected to the second end of the output coil of the transformer, the second end of the output coil of the transformer is connected to the ground, and the diode D2B is connected in parallel with the diode D2A.

7. The auxiliary power supply brown-out shutdown circuit of claim 6, wherein, The capacitor C3 and the resistor R10 and the resistor R11 are further included, the first end of the capacitor C3 is connected to the anode of the diode D2A, the first end of the capacitor C3 is connected to the first end of the resistor R10, the second end of the resistor R10 is connected to the cathode of the diode D2A, and the resistor R11 is connected in parallel with the resistor R10.

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