Low voltage DC redundant power supply control system

Abstract

A low-voltage direct current redundant power supply control system provided by the present invention comprises a transformer T1, a rectifier circuit Z1, a main power supply circuit, a battery BAT, a battery charging management circuit, a battery switching control circuit, a first relay, a second relay and a battery reverse connection detection control circuit; a normally closed switch K1 of the first relay is arranged in a power-on circuit of a primary winding of the transformer T1, a normally closed switch K2 of the second relay is arranged between a secondary winding of the transformer T1 and ground, and a battery reverse connection detection control circuit is used to detect whether the battery is reversely connected and control the first relay and the second relay to disconnect; a positive output end of the secondary winding of the transformer T1 is connected to an input end of the rectifier circuit Z1, an output end of the rectifier circuit Z1 is connected to an input end of a main power supply circuit, and an output end of the main power supply circuit supplies power to a load; an input end of the battery switching control circuit is connected to a positive pole of a battery BAT, an output end of the battery switching control circuit supplies power to a load, and a control input end of the battery switching control circuit is connected to a detection output end of the main power supply circuit.

Description

Technical Field

[0001] The invention relates to a power supply control system, in particular to a low-voltage direct current redundant power supply control system. Background Art

[0002] In DC power supply, a transformer is generally used to reduce the voltage of the AC power, rectify it, and then provide it to subsequent loads. However, the AC power is unstable during the power supply process, such as overvoltage, power outage, etc. In this case, it is necessary to perform overvoltage protection to switch the power supply of the AC power. However, after the power is cut off, for example, sensors in the Internet of Things need to collect continuous data in real time. Once the power supply is interrupted, it will cause data interruption, thereby affecting the monitoring and control of the Internet of Things. In the prior art, batteries and AC power are often used to form redundant power supply. However, the existing redundant power supply control system based on batteries often has a complex circuit structure and there is a switching lock phenomenon, and the conversion between batteries and AC power cannot be automatically completed. Although there are circuits that can convert, these circuits often rely on control chips, and their circuit structures are complex.

[0003] On the other hand, as part of the redundant power supply system, the battery often has the risk of reverse connection. In addition to preventing the entire system from working properly, the high voltage when powered on will reversely impact the secondary winding of the transformer, generating a high self-inductance electromotive force in the secondary winding, which will cause the secondary winding to burn out and even endanger subsequent circuits, causing the entire system to be damaged and collapse. Summary of the invention

[0004] In view of this, the present invention provides a low-voltage DC redundant power supply control system, which can switch to battery power supply in real time when the AC power fails during the low-voltage DC power supply process, and automatically switch to AC power supply after the AC power is restored, thereby ensuring the power supply stability of low-voltage DC electrical devices, and can accurately detect and immediately perform protection when the battery is reversed, thereby effectively ensuring the safety of the entire system.

[0005] A low-voltage DC redundant power supply control system provided by the present invention comprises a transformer T1, a rectifier circuit Z1, a main power supply circuit, a battery BAT, a battery charging management circuit, a battery switching control circuit, a first relay, a second relay and a battery reverse connection detection control circuit;

[0006] The first relay and the second relay are normally closed relays;

[0007] The normally closed switch K1 of the first relay is arranged in the power-on circuit of the primary winding of the transformer T1, and the normally closed switch K2 of the second relay is arranged between the secondary winding of the transformer T1 and the ground. The battery reverse connection detection control circuit is used to detect whether the battery is reversely connected and control the first relay and the second relay to be disconnected;

[0008] The positive output end of the secondary winding of the transformer T1 is connected to the input end of the rectifier circuit Z1, and the output end of the rectifier circuit Z1 is connected to the input end of the main power supply circuit, and the output end of the main power supply circuit supplies power to the load;

[0009] The input end of the battery charging management circuit is connected to the output end of the rectifier circuit, and the charging output end of the battery charging management circuit is connected to the positive electrode of the battery BAT;

[0010] The input end of the battery switching control circuit is connected to the positive electrode of the battery BAT, the output end of the battery switching control circuit supplies power to the load, and the control input end of the battery switching control circuit is connected to the detection output end of the main power supply circuit.

[0011] Further, the main power supply circuit includes an overvoltage detection circuit, a PMOS tube Q3 and a first MOS tube control circuit;

[0012] The drain of the PMOS tube Q3 is grounded through the capacitor C5, the drain of the PMOS tube Q3 serves as the output end of the main power supply circuit, the source of the PMOS tube Q3 serves as the input end of the main power supply circuit, the gate of the PMOS tube Q3 is connected to the control output end of the first MOS tube control circuit, the detection output end of the first MOS tube control circuit is connected to the control input end of the battery switching control circuit, the detection input end of the overvoltage detection circuit is connected to the source of the PMOS tube Q3, and the control output end of the overvoltage detection circuit is connected to the control input end of the first MOS tube control circuit.

[0013] Further, the first MOS tube control circuit includes a resistor R6, a resistor R7, a resistor R8, a resistor R9, a resistor R10, a transistor Q5, a transistor Q4 and a capacitor C4;

[0014] One end of the resistor R9 is connected to the source of the PMOS tube Q3, the other end of the resistor R9 is connected in parallel with the resistor R10 and the capacitor C4 and then grounded, the common connection point of the resistor R9 and the resistor R10 is connected to the base of the transistor Q5 through the resistor R6, the emitter of the transistor Q5 is grounded, the collector of the transistor Q5 is connected to the source of the PMOS tube Q3 through the resistor R7 and the resistor R8 in series, the common connection point of the resistor R7 and the resistor R8 serves as the control output end of the first MOS tube control circuit, the collector of the transistor Q4 is connected to the common connection point of the resistor R9 and the resistor R10, the emitter of the transistor Q4 is grounded, the base of the transistor Q4 serves as the control input end of the first MOS tube control circuit, and the common connection point of the resistor R9 and the resistor R10 serves as the detection output end of the first MOS tube control circuit.

[0015] Further, the overvoltage detection circuit includes a resistor R4, a resistor R5, a capacitor C3, a capacitor C6, a voltage regulator tube D1 and a voltage regulator tube D2;

[0016] One end of the resistor R4 is connected to the output end of the DC power supply, the other end of the resistor R4 is grounded through the resistor R5, the common connection point between the resistor R4 and the output end of the DC power supply is grounded through the capacitor C3, the common connection point between the resistor R4 and the resistor R5 is connected to the negative electrode of the Zener diode D1, the positive electrode of the Zener diode D1 is connected to the positive electrode of the Zener diode D2, the negative electrode of the Zener diode D2 serves as the control output end of the overvoltage detection circuit, and the positive electrode of the Zener diode D1 is grounded through the capacitor C6.

[0017] Further, the battery switching control circuit includes a resistor R1, a resistor R2, a resistor R3, a capacitor C1, a capacitor C2, a PMOS tube Q1 and a PMOS tube Q2;

[0018] The source of the PMOS tube Q1 is connected to the positive electrode of the battery BAT as the input end of the battery switching control circuit, the drain of the PMOS tube Q1 is used as the output end of the battery switching control circuit to supply power to the load, the source of the PMOS tube Q1 is grounded through the capacitor C1, the source of the PMOS tube Q1 is connected to the gate of the PMOS tube Q1 through the resistor R1, the gate of the PMOS tube Q1 is grounded through the capacitor C2, the gate of the PMOS tube Q1 is connected to the emitter of the transistor Q2 through the resistor R2, the collector of the transistor Q2 is grounded, the base of the transistor Q2 is connected to one end of the resistor R3, and the other end of the resistor R3 serves as the control input end of the battery switching control circuit.

[0019] Further, the battery reverse connection detection control circuit includes a resistor R11, a resistor R12, a resistor R13, a transistor Q6, a transistor Q7, a light emitting diode LED, a voltage regulator D3 and a voltage regulator D4;

[0020] The cathode of the voltage regulator tube D3 is connected to the source of the PMOS tube Q1, the anode of the voltage regulator tube D3 is connected to the cathode of the light emitting diode LED, and the anode of the light emitting diode LED is grounded through the resistor R11;

[0021] The positive electrode of the light emitting diode LED is connected to the base of the transistor Q6 and the transistor Q7, the collectors of the transistor Q6 and the transistor Q7 are both grounded, the emitter of the transistor Q6 is connected to one end of the excitation coil L1 of the first relay through the resistor R13, the other point of the excitation coil L1 of the first relay is connected to the positive electrode of the Zener diode D4, the negative electrode of the Zener diode D4 is connected to the negative electrode of the Zener diode D3, the emitter of the transistor Q7 is connected to one end of the excitation coil L2 of the second relay through the resistor R12, and the other end of the excitation coil L2 of the second relay is connected to the positive electrode of the Zener diode D4.

[0022] Furthermore, the battery charging management circuit is a CN3763 chip and its peripheral circuits.

[0023] The beneficial effects of the present invention are as follows: through the present invention, when a mains power failure occurs during the low-voltage DC power supply process, the system can switch to battery power supply in real time, and automatically switch to mains power supply after the mains power is restored, thereby ensuring the power supply stability of low-voltage DC electrical devices, and being able to accurately detect and immediately perform protection when the battery is reversely connected, thereby effectively ensuring the safety of the entire system. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0025] Figure 1 It is a circuit schematic diagram of the present invention.

[0026] Figure 2 It is a circuit diagram of a specific embodiment of the present invention. DETAILED DESCRIPTION

[0027] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0028] A low-voltage DC redundant power supply control system provided by the present invention comprises a transformer T1, a rectifier circuit Z1, a main power supply circuit, a battery BAT, a battery charging management circuit, a battery switching control circuit, a first relay, a second relay and a battery reverse connection detection control circuit;

[0029] The first relay and the second relay are normally closed relays;

[0030] The normally closed switch K1 of the first relay is arranged in the power-on circuit of the primary winding of the transformer T1, and the normally closed switch K2 of the second relay is arranged between the secondary winding of the transformer T1 and the ground. The battery reverse connection detection control circuit is used to detect whether the battery is reversely connected and control the first relay and the second relay to be disconnected;

[0031] The positive output end of the secondary winding of the transformer T1 is connected to the input end of the rectifier circuit Z1, and the output end of the rectifier circuit Z1 is connected to the input end of the main power supply circuit. The output end of the main power supply circuit supplies power to the load; the positive output end of the rectifier circuit Z1 is also grounded through a capacitor C7 for filtering. The rectifier circuit adopts a full-bridge rectifier circuit composed of existing diodes;

[0032] The input end of the battery charging management circuit is connected to the output end of the rectifier circuit, and the charging output end of the battery charging management circuit is connected to the positive electrode of the battery BAT;

[0033] The input end of the battery switching control circuit is connected to the positive pole of the battery BAT, the output end of the battery switching control circuit supplies power to the load, and the control input end of the battery switching control circuit is connected to the detection output end of the main power supply circuit. Through the above structure, it is possible to switch to battery power supply in real time when the mains fails during the low-voltage DC power supply process, and automatically switch to the mains after the mains is restored. The power supply stability of low-voltage DC electrical devices can be ensured, and accurate detection and immediate protection can be performed when the battery is reversely connected, thereby effectively ensuring the safety of the entire system. Among them, the system is also provided with an RC filter circuit and a voltage stabilizing circuit. After filtering the DC output of the main power supply circuit through the RC filter circuit, it is stabilized by the voltage stabilizing circuit. The voltage stabilizing circuit adopts an existing voltage stabilizing chip, such as LM7809, LM7805, AMS1117-3.3 and other voltage stabilizing chips; the rated working voltage of the electrical devices in actual working conditions is achieved, thereby ensuring the safety of electrical devices.

[0034] In this embodiment, the main power supply circuit includes an overvoltage detection circuit, a PMOS tube Q3 and a first MOS tube control circuit;

[0035] The drain of the PMOS tube Q3 is grounded through the capacitor C5, the drain of the PMOS tube Q3 serves as the output end of the main power supply circuit, the source of the PMOS tube Q3 serves as the input end of the main power supply circuit, the gate of the PMOS tube Q3 is connected to the control output end of the first MOS tube control circuit, the detection output end of the first MOS tube control circuit is connected to the control input end of the battery switching control circuit, the detection input end of the overvoltage detection circuit is connected to the source of the PMOS tube Q3, and the control output end of the overvoltage detection circuit is connected to the control input end of the first MOS tube control circuit.

[0036] Specifically:

[0037] The first MOS tube control circuit includes a resistor R6, a resistor R7, a resistor R8, a resistor R9, a resistor R10, a transistor Q5, a transistor Q4 and a capacitor C4;

[0038] One end of the resistor R9 is connected to the source of the PMOS tube Q3, the other end of the resistor R9 is connected in parallel with the resistor R10 and the capacitor C4 and then grounded, the common connection point of the resistor R9 and the resistor R10 is connected to the base of the transistor Q5 through the resistor R6, the emitter of the transistor Q5 is grounded, the collector of the transistor Q5 is connected to the source of the PMOS tube Q3 through the resistor R7 and the resistor R8 in series, the common connection point of the resistor R7 and the resistor R8 serves as the control output end of the first MOS tube control circuit, the collector of the transistor Q4 is connected to the common connection point of the resistor R9 and the resistor R10, the emitter of the transistor Q4 is grounded, the base of the transistor Q4 serves as the control input end of the first MOS tube control circuit, and the common connection point of the resistor R9 and the resistor R10 serves as the detection output end of the first MOS tube control circuit.

[0039] The overvoltage detection circuit includes a resistor R4, a resistor R5, a capacitor C3, a capacitor C6, a voltage regulator tube D1 and a voltage regulator tube D2;

[0040] One end of the resistor R4 is connected to the output end of the DC power supply, the other end of the resistor R4 is grounded through the resistor R5, the common connection point between the resistor R4 and the output end of the DC power supply is grounded through the capacitor C3, the common connection point between the resistor R4 and the resistor R5 is connected to the negative electrode of the Zener diode D1, the positive electrode of the Zener diode D1 is connected to the positive electrode of the Zener diode D2, the negative electrode of the Zener diode D2 serves as the control output end of the overvoltage detection circuit, and the positive electrode of the Zener diode D1 is grounded through the capacitor C6.

[0041] The battery switching control circuit includes a resistor R1, a resistor R2, a resistor R3, a capacitor C1, a capacitor C2, a PMOS tube Q1 and a PMOS tube Q2;

[0042] The source of the PMOS tube Q1 is connected to the positive electrode of the battery BAT as the input end of the battery switching control circuit, the drain of the PMOS tube Q1 is used as the output end of the battery switching control circuit to supply power to the load, the source of the PMOS tube Q1 is grounded through the capacitor C1, the source of the PMOS tube Q1 is connected to the gate of the PMOS tube Q1 through the resistor R1, the gate of the PMOS tube Q1 is grounded through the capacitor C2, the gate of the PMOS tube Q1 is connected to the emitter of the transistor Q2 through the resistor R2, the collector of the transistor Q2 is grounded, the base of the transistor Q2 is connected to one end of the resistor R3, and the other end of the resistor R3 is used as the control input end of the battery switching control circuit. Under the above structure, the power supply between the mains and the battery can be stably controlled to switch freely without other chip control, and the circuit structure is stable and reliable.

[0043] When the mains power supply is normal, the base of transistor Q5 is divided by resistors R9 and R10 to supply power, transistor Q5 is turned on, thereby PMOS tube Q3 is turned on, and the main power supply circuit supplies power. At the same time, due to the voltage applied to the base of transistor Q2, the emitter voltage of transistor Q2 is less than the base voltage through the parameter control of resistors R3, R2 and R1, and transistor Q2 is turned off, thereby PMOS tube Q1 is turned off, and the battery switching control circuit does not supply power to the load;

[0044] When the mains is interrupted, there is no output at the common connection point of resistor R9 and resistor R10; when there is overvoltage in the mains, diode D1 is turned on, capacitor C6 is filtered and applied to transistor Q4, transistor Q4 is turned on, and the potential of the common connection point of resistor R9 and resistor R10 is pulled down. Both of these states will cause the base voltage of transistor Q2 to be set to 0, transistor Q2 is turned on, and thus PMOS tube Q1 is turned on, and the battery supplies power to the load. When the mains is restored, transistor Q2 is turned off again, and PMOS tube Q1 is turned off, thereby completing automatic switching.

[0045] In this embodiment, the battery reverse connection detection control circuit includes a resistor R11, a resistor R12, a resistor R13, a transistor Q6, a transistor Q7, a light emitting diode LED, a voltage regulator D3 and a voltage regulator D4;

[0046] The cathode of the voltage regulator tube D3 is connected to the source of the PMOS tube Q1, the anode of the voltage regulator tube D3 is connected to the cathode of the light emitting diode LED, and the anode of the light emitting diode LED is grounded through the resistor R11;

[0047] The positive electrode of the light emitting diode LED is connected to the base of the transistor Q6 and the transistor Q7. The collectors of the transistor Q6 and the transistor Q7 are both grounded. The emitter of the transistor Q6 is connected to one end of the excitation coil L1 of the first relay through the resistor R13. The other end of the excitation coil L1 of the first relay is connected to the voltage regulator tube D4. The positive electrode of the first relay and the negative electrode of the voltage regulator D4 are connected, the negative electrode of the voltage regulator D3 is connected, the emitter of the transistor Q7 is connected to one end of the excitation coil L2 of the second relay through the resistor R12, and the other end of the excitation coil L2 of the second relay is connected to the positive electrode of the voltage regulator D4. Through the above structure, the transformer itself and the subsequent circuits of the transformer can be well protected; when the battery is reversely connected, the ground terminal becomes a high level. At this time, the positive electrode of the battery, the resistor R11, the light-emitting diode LED, the voltage regulator D3 and the negative electrode of the battery form a loop. At this time, the light-emitting diode LED emits light for reverse connection alarm; on the other hand, the transistors Q6 and Q7 are turned on, the excitation coils of the first relay and the second relay are energized, the normally closed switch K1 of the first relay and the normally closed switch K2 of the second relay are disconnected under the action of electromagnetic force, the voltage of the battery will not be loaded on the secondary winding of the transformer T1, and the primary winding of the transformer T1 is also disconnected from the mains, thereby playing a good protective role.

[0048] In this embodiment, the battery charging management circuit is a CN3763 chip and its peripheral circuits. Of course, other battery charging management circuits may also be used, such as a TP5400 chip and its peripheral circuits, and the battery uses an existing lithium battery.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A low voltage DC redundant power supply control system, characterized in that: It includes a transformer T1, a rectifier circuit Z1, a main power supply circuit, a battery BAT, a battery charging management circuit, a battery switching control circuit, a first relay, a second relay and a battery reverse connection detection control circuit; The first relay and the second relay are normally closed relays; The normally closed switch K1 of the first relay is arranged in the power-on circuit of the primary winding of the transformer T1, and the normally closed switch K2 of the second relay is arranged between the secondary winding of the transformer T1 and the ground. The battery reverse connection detection control circuit is used to detect whether the battery is reversely connected and control the first relay and the second relay to be disconnected; The positive output end of the secondary winding of the transformer T1 is connected to the input end of the rectifier circuit Z1, the output end of the rectifier circuit Z1 is connected to the input end of the main power supply circuit, and the output end of the main power supply circuit supplies power to the load; The input end of the battery charging management circuit is connected to the output end of the rectifier circuit, and the charging output end of the battery charging management circuit is connected to the positive electrode of the battery BAT; The input end of the battery switching control circuit is connected to the positive electrode of the battery BAT, the output end of the battery switching control circuit supplies power to the load, and the control input end of the battery switching control circuit is connected to the detection output end of the main power supply circuit; The main power supply circuit includes an overvoltage detection circuit, a PMOS tube Q3 and a first MOS tube control circuit; The drain of the PMOS tube Q3 is grounded through the capacitor C5, the drain of the PMOS tube Q3 serves as the output end of the main power supply circuit, the source of the PMOS tube Q3 serves as the input end of the main power supply circuit, the gate of the PMOS tube Q3 is connected to the control output end of the first MOS tube control circuit, the detection output end of the first MOS tube control circuit is connected to the control input end of the battery switching control circuit, the detection input end of the overvoltage detection circuit is connected to the source of the PMOS tube Q3, and the control output end of the overvoltage detection circuit is connected to the control input end of the first MOS tube control circuit; The battery switching control circuit includes a resistor R1, a resistor R2, a resistor R3, a capacitor C1, a capacitor C2, a PMOS tube Q1 and a PMOS tube Q2; The source of the PMOS tube Q1 is connected to the positive electrode of the battery BAT as the input end of the battery switching control circuit, the drain of the PMOS tube Q1 is used as the output end of the battery switching control circuit to supply power to the load, the source of the PMOS tube Q1 is grounded through the capacitor C1, the source of the PMOS tube Q1 is connected to the gate of the PMOS tube Q1 through the resistor R1, the gate of the PMOS tube Q1 is grounded through the capacitor C2, the gate of the PMOS tube Q1 is connected to the emitter of the transistor Q2 through the resistor R2, the collector of the transistor Q2 is grounded, the base of the transistor Q2 is connected to one end of the resistor R3, and the other end of the resistor R3 serves as the control input end of the battery switching control circuit; The battery reverse connection detection control circuit comprises a resistor R11, a resistor R12, a resistor R13, a transistor Q6, a transistor Q7, a light emitting diode LED, a voltage regulator D3 and a voltage regulator D4; The cathode of the voltage regulator tube D3 is connected to the source of the PMOS tube Q1, the anode of the voltage regulator tube D3 is connected to the cathode of the light emitting diode LED, and the anode of the light emitting diode LED is grounded through the resistor R11; The positive electrode of the light emitting diode LED is connected to the base electrodes of the transistor Q6 and the transistor Q7, the collector electrodes of the transistor Q6 and the transistor Q7 are both grounded, the emitter of the transistor Q6 is connected to one end of the excitation coil L1 of the first relay through the resistor R13, the other point of the excitation coil L1 of the first relay is connected to the positive electrode of the voltage regulator tube D4, the negative electrode of the voltage regulator tube D4 is connected to the negative electrode of the voltage regulator tube D3, the emitter of the transistor Q7 is connected to one end of the excitation coil L2 of the second relay through the resistor R12, and the other end of the excitation coil L2 of the second relay is connected to the positive electrode of the voltage regulator tube D4.

2. The low voltage DC redundant power supply control system according to claim 1, characterized in that: The first MOS tube control circuit includes a resistor R6, a resistor R7, a resistor R8, a resistor R9, a resistor R10, a transistor Q5, a transistor Q4 and a capacitor C4; One end of the resistor R9 is connected to the source of the PMOS tube Q3, the other end of the resistor R9 is connected in parallel with the resistor R10 and the capacitor C4 and then grounded, the common connection point of the resistor R9 and the resistor R10 is connected to the base of the transistor Q5 through the resistor R6, the emitter of the transistor Q5 is grounded, the collector of the transistor Q5 is connected to the source of the PMOS tube Q3 through the resistor R7 and the resistor R8 in series, the common connection point of the resistor R7 and the resistor R8 serves as the control output end of the first MOS tube control circuit, the collector of the transistor Q4 is connected to the common connection point of the resistor R9 and the resistor R10, the emitter of the transistor Q4 is grounded, the base of the transistor Q4 serves as the control input end of the first MOS tube control circuit, and the common connection point of the resistor R9 and the resistor R10 serves as the detection output end of the first MOS tube control circuit.

3. The low voltage DC redundant power supply control system according to claim 1, characterized in that: The overvoltage detection circuit includes a resistor R4, a resistor R5, a capacitor C3, a capacitor C6, a voltage regulator tube D1 and a voltage regulator tube D2; One end of the resistor R4 is connected to the output end of the DC power supply, the other end of the resistor R4 is grounded through the resistor R5, the common connection point between the resistor R4 and the output end of the DC power supply is grounded through the capacitor C3, the common connection point between the resistor R4 and the resistor R5 is connected to the negative electrode of the Zener diode D1, the positive electrode of the Zener diode D1 is connected to the positive electrode of the Zener diode D2, the negative electrode of the Zener diode D2 serves as the control output end of the overvoltage detection circuit, and the positive electrode of the Zener diode D1 is grounded through the capacitor C6.

4. The low voltage DC redundant power supply control system according to claim 1, characterized in that: The battery charging management circuit is a CN3763 chip and its peripheral circuits.

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