CN1983761A - Controller for switching main power supply - Google Patents

Abstract

The present invention is applicable to the field of circuit control, and provides a switching control device for main and standby power supplies, the device includes: a main circuit that controls the opening and closing of the power supply path of the main circuit according to the voltage difference between the main circuit power supply voltage and the output voltage of the combined circuit switching control unit; and a backup switching control unit that controls the opening and closing of the backup power supply path according to the voltage difference between the main power supply voltage and the reference voltage; the main circuit switching control unit and the backup switching control unit respectively include a control power supply path opening low dropout switching components with turn-off. In the present invention, an active switch is used as a switching device for switching between main and standby power sources, which improves switching action, reduces voltage drop and loss, is suitable for low-voltage circuits, and realizes the same isolation function as a diode. At the same time, the uninterrupted switching of the two power sources is realized, which improves the reliability of the system, and all devices can be surface-mounted for easy heat dissipation.

Description

A switching control device for main and standby power supplies

technical field

The invention belongs to the field of circuit control, in particular to a switching control device for main and standby power supplies.

Background technique

In a low-voltage two-way or multi-way power supply system, the main power supply usually supplies power to the load. If the main power supply fails and cannot supply power to the load, switch to the backup power supply, and the backup power supply supplies power to the load. Both the main power supply and the backup power supply use diodes as isolation modules to prevent the backup power from flowing back into the main power supply after the main power supply fails.

Figure 1 shows the composition of a main-standby power switching circuit that adopts diode isolation in a multi-channel power supply system, and the circuit includes multiple main-circuit power supplies and a backup power supply. When diodes are used to isolate the main power supply and backup power supply, when the main and backup power supplies are both low voltage, due to the high voltage drop of the isolation diode, the main power supply will generate a large voltage drop on the diode (minimum 0.4V). In addition, the ambient temperature will have a greater impact on the voltage drop of the diode, causing the voltage to be too low after the circuit is combined, and the output of the circuit to supply power to the load is not normal.

Contents of the invention

The purpose of the present invention is to provide a switching circuit for main and standby power supplies, aiming to solve the problem of overvoltage after the circuit is combined due to the large forward voltage drop when the main and standby power supplies are isolated by diodes in the prior art multi-channel low-voltage circuit power supply system. Low, the problem of abnormal power supply to the load.

In order to achieve the purpose of the above invention, the present invention provides a switching control device for main and standby power supplies, said device comprising:

A main circuit switching control unit that controls the opening and closing of the main circuit power supply path according to the voltage difference between the main circuit power supply voltage and the combined output voltage; and

A standby switching control unit that controls the opening and closing of the standby power supply path according to the voltage difference between the main power supply voltage and the reference voltage;

The main circuit switching control unit and the standby switching control unit respectively include a low-voltage drop switching element for controlling the opening and closing of the power supply path.

The master switch control unit includes:

The main circuit sampling module that collects the main circuit power supply voltage and combined output voltage;

A main circuit control module that is connected to the main circuit sampling module and outputs a switching control signal according to the voltage difference between the main circuit power supply voltage and the combined output voltage collected by the main circuit sampling module; and

The main circuit isolation module is connected with the main circuit control module and controls the opening and closing of the main circuit power path according to the switching control signal, and the main circuit isolation module includes a low-voltage drop switch component.

The standby switching control unit includes:

A standby sampling module for collecting main power supply voltage and reference voltage;

A standby control module that outputs a switching control signal according to the voltage difference between the main power supply voltage and the reference voltage collected by the standby sampling module; and

Connected with the backup control module, a backup isolation module that controls the opening and closing of the backup power supply path according to the switching control signal, the backup isolation module includes a low-voltage drop switch element.

The main road control module further includes:

When the voltage of the main power supply drops, the hysteresis circuit module that increases the voltage difference between the output voltage of the combined circuit and the voltage of the main power supply.

The backup control module further includes:

When the voltage of the main power supply rises, the hysteresis circuit module that increases the voltage difference between the main power supply voltage and the reference voltage.

The standby switching control unit further includes:

It is connected with the backup control module and the backup isolation module, and according to the switch control signal of the backup control module, the input level of the low-voltage drop switch component is accelerated, and the backup isolation module is controlled to accelerate the opening of the backup power supply path. Activate the module.

The reference voltage is a backup power supply voltage or a reference voltage.

The low voltage drop component is a MOS transistor or a high power transistor.

The accelerated turn-on module includes a triode or MOS transistor.

In the present invention, the active switch is used as the switching device for switching between the main and standby power supplies, which improves the switching action, reduces the voltage drop and loss, and the voltage drop before and after the isolation circuit is very small (20A is only about 50mV), which is suitable for low-voltage circuits and realizes the same Diodes have the same isolation effect. At the same time, the uninterrupted switching of the two power sources is realized, which improves the reliability of the system, and all devices can be surface-mounted for easy heat dissipation.

Description of drawings

Fig. 1 is a schematic diagram of a power supply circuit in which the main and standby power supplies are isolated by diodes in the prior art;

Fig. 2 is a schematic diagram of the realization of the main and standby power supply switching device in the first embodiment of the present invention;

Fig. 3 is an example diagram of the circuit structure of the main and standby power switching device in the first embodiment of the present invention;

Fig. 4 is a schematic diagram of the realization of the master-standby power switching device according to the second embodiment of the present invention;

Fig. 5 is an example diagram of the circuit structure of the master-standby power switching device in the second embodiment of the present invention;

Fig. 6 is a schematic diagram of the implementation of the main and standby power supply switching device with the hysteresis circuit added in the first embodiment of the present invention;

Fig. 7 is a realization schematic diagram of the main-standby power switching device with the addition of a hysteresis circuit in the second embodiment of the present invention;

Fig. 8 is an example diagram of the circuit structure of the main-standby power switching device with a hysteresis circuit added in the first embodiment of the present invention;

Fig. 9 is an example diagram of the circuit structure of the main-standby power switching device with a hysteresis circuit added in the second embodiment of the present invention;

Fig. 10 is a schematic diagram of the realization of the main and standby power switching device with an accelerated turn-on circuit added in the first embodiment of the present invention;

Fig. 11 is a schematic diagram of the realization of the master-standby power switching device with an accelerated turn-on circuit added in the second embodiment of the present invention;

Fig. 12 is an example diagram of the circuit structure of the main-standby power switching device with an accelerated turn-on circuit added in the first embodiment of the present invention;

Fig. 13 is an example diagram of the circuit structure of the main-standby power switching device with an accelerated turn-on circuit added in the second embodiment of the present invention;

Fig. 14 is a schematic diagram of the realization of the main-standby power switching device with hysteresis circuit and accelerated turn-on circuit added in the first embodiment of the present invention;

Fig. 15 is a schematic diagram of the realization of the main-standby power switching device with hysteresis circuit and accelerated turn-on circuit added in the second embodiment of the present invention;

Fig. 16 is an example diagram of the circuit structure of the main-standby power switching device with hysteresis circuit and accelerated turn-on circuit added in the first embodiment of the present invention;

Fig. 17 is an example diagram of the circuit structure of the main/standby power switching device with hysteresis circuit and accelerated turn-on circuit added in the second embodiment of the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

The invention adopts the low-voltage drop components as the isolation device for the main circuit power supply and the backup power supply, forms a low-voltage drop isolation circuit with other circuit components, and realizes the isolation of the main circuit power supply and the backup power supply. By comparing the voltage difference between the main power supply and the backup power supply and the combined output voltage, the on and off of the isolation device is controlled, and the main power supply and the backup power supply are switched flexibly to ensure the normal operation of the power supply system.

In the present invention, a device with a lower voltage drop is selected as the isolation device for the main power supply and the backup power supply, such as a metal-oxide-semiconductor field effect transistor (Metal-Oxide-Semiconductor Field Effect Transistor, MOSFET/MOS), a high-power transistor, etc. device, the specific implementation of the present invention will be described in detail below by taking a MOS transistor as an example. Since the MOS tube has bidirectional conductivity, a reasonable control device must be used to turn on and off the gate of the MOS tube, so as to achieve the purpose of effective isolation. The invention controls the opening and closing of the MOS tube through a differential pressure control method.

In the first embodiment of the present invention, the main circuit isolation is turned on and off by detecting the voltage difference between the main circuit power supply voltage and the combined output voltage, and the backup isolation is controlled by detecting the voltage difference between the main circuit power supply voltage and the reference voltage accomplish.

As shown in Figure 2, the main road sampling module 101.1 collects the main road power supply voltage and the combined output voltage, and the main road control module 102.1 is based on the voltage difference between the main road power supply voltage and the combined output voltage collected by the main road sampling module 101.1. The switch of the road isolation module 103.1 is controlled. When the voltage of the main power supply is higher than a certain voltage difference (generally 15-20mV) of the combined output voltage, the main circuit isolation module 103.1 is controlled to open, and the main power supply path is connected; otherwise, it is turned off, and the main power supply path is shut off.

The backup sampling module 101.2 collects the main power supply voltage and the reference voltage, and the backup control module 102.2 controls the switch of the backup isolation module 103.2 according to the voltage difference between the main power supply voltage and the reference voltage collected by the backup sampling module 101.2. When the main power supply voltage is lower than the reference voltage, the backup control module 102.2 controls the backup isolation module 103.2 to open, and the backup power supply path is connected; otherwise, it is turned off, and the backup power supply path is turned off. In the present invention, the reference voltage is provided by a stable voltage source with high precision.

When the circuit starts to work, the main circuit power supply voltage is higher than the reference voltage, and the standby control module 102.2 controls the standby isolation module 103.2 to shut down; The isolation module 103.1 is turned on, and the main power supply supplies power to the load. When the main power supply does not work normally, the main power supply voltage begins to drop. When the voltage difference between the main power supply voltage and the combined output voltage is less than a certain voltage difference, the main circuit control module 102.1 controls the main circuit isolation module 103.1 to shut down. When the voltage of the main power supply continues to drop below the reference voltage, the backup control module 102.2 controls the backup isolation module 103.2 to turn on, and switches to the backup power supply to supply power to the load.

FIG. 3 shows an example of the circuit structure of this embodiment, and a P-channel enhanced MOSFET is used as an isolation device for the main power supply and the backup power supply.

One end of the resistor R1 is grounded, the other end is connected to the resistor R3, the resistor R3 is connected in series with the resistor R4, and the resistor R4 is connected to the main power supply (Z 3V3). The resistor R3 and the resistor R4 are connected in series with the resistor R1 to divide the voltage of the main power supply, and the divided output is used as the reference voltage of the comparator U1A. The resistor R2 and the resistor R5 divide the combined output voltage, and the divided output is used as another reference voltage of the comparator U1A. R1=R2, R3=R5, resistor R4 is an adjustable resistor, by adjusting the resistor R4 can ensure that Q1 is turned on only when the main power supply voltage is higher than the combined output voltage by a certain voltage, so that the main power supply voltage drops below the combined circuit Before the output voltage, Q1 is turned off in advance, which reduces the possibility of backup power flowing into the main power supply after the main power supply fails.

The positive and negative input terminals of the comparator U1A are connected in parallel with the capacitor C1, and the function of the capacitor C1 is filtering. One end of the pull-up resistor R6 is connected to the output end of the comparator U1A, and the other end is connected to the anode of the comparator U1A.

The gate (G pole) of the MOS transistor Q1 is connected to the output terminal of U1A of the comparator, the source (S pole) is connected to the main power supply, and the drain (D pole) outputs the combined output voltage. When the main power supply voltage is normal, the voltage at the negative input terminal of comparator U1A is higher than the voltage at the positive input terminal of U1A, and U1A outputs a low level. Since Q1 is turned on at a low level, Q1 is turned on at this time. When the voltage of the main power supply is abnormal, when the voltage of the negative input terminal of U1A is lower than the voltage of the positive input terminal, the output is open, and the pull-up resistor R6 outputs a high level, the gate of Q1 is pulled high, and Q1 is turned off.

One end of the resistor R8 is grounded, and the other end is connected to the resistor R7. The resistor R7 and the resistor R8 divide the main power supply voltage as a reference voltage of the comparator U1B, and the reference voltage (3V3) is used as the other reference voltage of the comparator U1B.

The positive and negative input terminals of the comparator U1B are connected in parallel with the capacitor C2, and the function of the capacitor C2 is filtering. One end of the pull-up resistor R12 is connected to the output end of the comparator U1B, and the other end is connected to the anode of the comparator U1B.

The gate (G pole) of the MOS transistor Q2 is connected to the output terminal of U1B of the comparator, the source (S pole) is connected to the backup power supply (B 3V3), and the drain (D pole) outputs the combined output voltage. When the main power supply voltage is constant, the voltage at the positive input terminal of the comparator U1B is higher than the voltage at the negative input terminal of U1B, the output of U1B is open, the pull-up resistor R13 outputs a high level, the gate of Q2 is pulled high, and Q2 is turned off. When the voltage of the main power supply is abnormal, when the voltage at the positive input terminal of U1B is lower than the voltage at the negative input terminal, it outputs a low level, and Q2 is turned on at this time.

The anodes of U1A and U1B are respectively connected to the cathodes of diodes D2 and D1, the anode of diode D1 is connected to the backup power supply, and the anode of D2 is connected to the output voltage of the circuit, and UIA and UIB are powered by the backup power supply voltage and the combined output voltage. In order to prevent current backflow, the voltage of the backup power supply and the combined output voltage supply power to the comparators U1B and U1A through diodes D1 and D2 respectively, and the function of C3 is to maintain the normal power supply of the comparators U1A and U1B when both the main and backup voltages drop.

As a second embodiment of the present invention, as shown in FIG. 4 , the backup isolation is controlled by detecting the voltage difference between the main power supply voltage and the backup power supply voltage. Wherein, the switch control principle of the main road isolation module 103.1 is the same as that of the first embodiment, and will not be repeated here.

The backup sampling module 101.2 collects the main power supply voltage and the backup power supply voltage, and the backup control module 102.2 controls the switching of the backup isolation module 103.2 according to the voltage difference between the main road power supply voltage and the backup power supply voltage. When the main power supply voltage is lower than the backup power supply voltage, the backup control module 102.2 controls the backup isolation module 103.2 to open, and the backup power supply path is connected; otherwise, it is turned off, and the backup power supply path is turned off.

When the main power supply starts to work, if the voltage of the main power supply is higher than the voltage of the backup power supply, the backup control module 102.2 controls the backup isolation module 103.2 to shut down; The main circuit isolation module 103.1 is controlled to be turned on, and the main circuit power supply supplies power to the load. When the main power supply does not work normally, the main power supply voltage begins to drop. When the voltage difference between the main power supply voltage and the combined output voltage is less than a certain voltage difference, the main circuit control module 102.1 controls the main circuit isolation module 103.1 to shut down. When the main power supply voltage continues to drop below the backup power supply voltage, the backup control module 102.2 controls the backup isolation module 103.2 to turn on, and switches to the backup power supply to supply power to the load.

Figure 5 shows an example of the circuit structure in this embodiment, R8=R9, R7=R10, resistor R11 is an adjustable resistor, resistor R8 and resistor R7 divide the voltage of the main power supply voltage as a reference voltage of the comparator U1B , one end of the resistor R9 is grounded, the other end is connected to the resistor R10, and the resistor R10 and the resistor R11 are connected in series with the resistor R9 to divide the standby power supply voltage as another reference voltage. By adjusting the resistor R11, Q2 can be turned on only when the voltage of the main power supply is lower than the voltage of the backup power supply, and the power supply is supplied by the backup power supply.

Under normal circumstances, the main circuit is normal, that is, the voltage of the main circuit power supply is higher than a certain value of the combined output voltage (adjusted by the resistor R4), and it is also higher than the standby power supply voltage. , U1A outputs low level, Q1 is turned on, U1B input positive terminal voltage is higher than input negative terminal voltage, U1B output is open circuit, Q2 is disconnected, powered by the main power supply; when the main power supply voltage drops below a certain value of the backup power supply voltage ( When adjusted by resistor R11), the voltage of the main circuit power supply is lower than the output voltage of the combined circuit, so the voltage at the negative input terminal of U1A is lower than the voltage at the positive input terminal, U1A outputs a high level, and Q1 is disconnected. The positive terminal voltage of U1B input is lower than the negative terminal voltage, U1B outputs a low level, Q2 is turned on, and the power is supplied by the backup power supply at this time. The working principles of the rest of the circuits are the same as those of the first embodiment and will not be repeated here.

In order to enhance the anti-interference performance of the system, in another embodiment of the present invention, a hysteresis circuit module 102.21 can be added in the standby control module 102.2, as shown in Figure 6 and Figure 7, so that when the main power supply voltage drops, To increase the voltage difference between the combined output voltage and the mains power supply voltage, the corresponding circuit structure examples are shown in Figure 8 and Figure 9 respectively.

Wherein, one end of the resistor R14 is connected to the negative input end of the comparator U1B, the other end is connected to the positive pole of the diode D3, and the negative pole of D3 is connected to the output end of the comparator U1B. When the power supply voltage of the main circuit is normal, the output of U1B is open circuit, the diode D3 is reversely cut off, and the resistor R7 and resistor R8 divide the voltage as the input reference voltage. When the main power supply is undervoltage, U1B outputs a low level, D3 is forward-conducting, and the input reference voltage is the divided voltage of resistor R7 and resistor R8//resistor R14 (resistor after resistor R8 and resistor R14 are connected in parallel), so the main circuit When the power supply voltage rises, the backup isolation channel must be higher than the reference voltage or the backup power supply voltage by a certain value, which enhances the anti-interference performance of the system. Similarly, a hysteresis circuit can also be added in the main circuit control module 102.1, so that when the main circuit power supply voltage rises, the voltage difference between the main circuit power supply voltage and the reference voltage is increased to increase the anti-interference performance of the system. The circuit structure and working principle are the same as those described above, and will not be repeated here.

In order to speed up the opening of the standby isolation module 103.2 and increase the switching speed of the main and standby power sources, in another embodiment of the present invention, as shown in Figure 10 and Figure 11, an accelerated opening module 104 is added above the standby isolation module 103.2 to accelerate The enabling module 104 may select a triode, a MOS transistor or other switching devices.

Fig. 12 and Fig. 13 show examples of the circuit structure of this embodiment, using an NPN transistor Q4 as an acceleration device. The emitter of the transistor Q4 is grounded, the base is connected to the output terminal of the comparator U1B, and the collector is connected to the gate of the MOS transistor Q2. When the main power supply is normal, U1B outputs a low level. According to the working principle of the NPN transistor, the transistor Q4 and Q2 are disconnected when the low level is low; The pole is quickly pulled down, Q2 is turned on, and the backup isolation channel is accelerated to open.

As a preferred embodiment of the present invention, as shown in FIG. 14 and FIG. 15 , a hysteresis circuit module and an accelerated turn-on module can be added at the same time. The examples of the circuit structure in this optimized embodiment are shown in Figures 16 and 17, and the specific working principles are as described above, and will not be repeated here.

The present invention can also be applied to the situation of N+1 backup. When N+1 backup is concentrated, the main power supply of N routes supplies power to the system at the same time, and the backup power supply of 1 route is in the backup state. The standby control module controls the signal of the standby isolation module 103.2 to control the standby isolation module 103.2 after passing through the OR gate. When any main power supply of N circuits fails, the backup power supply is triggered to supply power to the system through the OR gate to ensure that the system always supplies power to N circuits. When N+1 backup is used, it can also be applied to the above-mentioned embodiments, and the specific implementation principle and circuit structure will not be repeated here.

Compared with the original diode isolation circuit, the present invention adds devices such as comparator (failure rate 16FIT), MOS tube (failure rate 17FIT) and triode (failure rate 2FIT) and resistors and capacitors, and the total failure rate is 35FIT, which is isolated from the original diode The failure rate of the circuit is basically the same as 32FIT, and the reliability is high.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be included in the protection of the present invention. within range.

Claims (9)

1, a kind of switching control of main power supply is characterized in that, described device comprises:

Control the main road switch control unit that main road power supply supply access is opened and turn-offed according to main road supply voltage and the pressure reduction that closes the road output voltage; And

Pressure reduction according to main road supply voltage and reference voltage is controlled the standby switch control unit that the stand-by power supply supply access is opened and turn-offed;

Described main road switch control unit and standby switch control unit comprise the low pressure drop switching component that a control power path is opened and turn-offed respectively.

2, the switching control of main power supply as claimed in claim 1 is characterized in that, described main road switch control unit comprises:

Gather main road supply voltage and the main road sampling module that closes the road output voltage;

Be connected with described main road sampling module, according to the main road supply voltage of main road sampling module collection and the main road control module of closing the pressure reduction output switch-over control signal of road output voltage; And

Be connected with described main road control module, according to the main road isolation module that described switch-over control signal control main road power path is opened and turn-offed, described main road isolation module comprises a low pressure drop switching component.

3, the switching control of main power supply as claimed in claim 1 is characterized in that, described standby switch control unit comprises:

Gather the standby sampling module of main road supply voltage and reference voltage;

The standby control module of the main road supply voltage of gathering according to standby sampling module and the pressure reduction output switch-over control signal of reference voltage; And

Be connected with described standby control module, according to the standby isolation module that described switch-over control signal control stand-by power supply supply access is opened and turn-offed, described standby isolation module comprises a low pressure drop switching component.

4, the switching control of main power supply as claimed in claim 2 is characterized in that, described main road control module further comprises:

When the main road supply voltage falls, heighten the return difference circuit module that closes pressure difference between road output voltage and the main road supply voltage.

5, the switching control of main power supply as claimed in claim 3 is characterized in that, described standby control module further comprises:

When the main road supply voltage gos up, heighten the return difference circuit module of pressure difference between main road supply voltage and the reference voltage.

6, the switching control of main power supply as claimed in claim 3 is characterized in that, described standby switch control unit further comprises:

Be connected with standby isolation module with described standby control module, switch-over control signal according to described standby control module, acceleration drags down the incoming level of low pressure drop switching component, controls the acceleration that described standby isolation module quickens to open the stand-by power supply supply access and opens module.

As the switching control of claim 3 or 5 described main power supplies, it is characterized in that 7, described reference voltage is backup power source voltage or reference voltage.

As the switching control of claim 2 or 3 described main power supplies, it is characterized in that 8, described low pressure drop components and parts are metal-oxide-semiconductor or high power transistor.

9, the switching control of main power supply as claimed in claim 1 is characterized in that, described acceleration is opened module and comprised a triode or metal-oxide-semiconductor.

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