CN205791781U - Power-supply system automatic switch-over circuit - Google Patents

Abstract

The utility model relates to an automatic switching circuit of a power supply system, which is characterized in that it comprises a relay one with a normally closed contact, a relay two with a normally open contact and a delay control unit, one end of the normally closed contact of the relay one, One end of the normally open contact of relay 2 is respectively connected to power supply 1 and the selected power supply 2, the other end of the normally closed contact of relay 1, the other end of the normally open contact of relay 2 are connected to the common power supply output circuit Connected, the power supply 2 provides the working voltage for the delay control unit. The delay control unit includes a power-off delay control sub-circuit and a power-on delay control sub-circuit, and the power-off delay control sub-circuit and the power-on delay control sub-circuit respectively control The normally closed contact of relay one and the normally open contact of relay two open and close. The beneficial effect of the utility model is that: two relays and one delay control unit are adopted, the structure is simple, the cost is low, and the interconnection of two power sources caused by electric arc is avoided.

Description

Power system automatic switching circuit

technical field

The utility model relates to a switching circuit used when two power supplies supply power to the same power supply object, and the two power supplies realize switching power supply through the switching circuit.

Background technique

In the field of electric power, it is often the case that two power sources are used to supply power to the power supply object. The two power sources are switched through a switching circuit. The switching circuit usually uses a transfer switch, a relay, a contactor, etc. as the main components. The existing switching circuit has the following problems:

1. Realize power switching through the transfer switch. The power supply one supplies power through one end of the switch gear position one switch, the power supply two supplies power through one end of the conversion switch gear position two switch, the other end of the gear position one switch and the other end of the gear position two switch are connected, and are connected to the power supply object. Turn the switch to gear one, and the power supply object is powered by power supply one; turn the switch to gear two, and the power supply object is powered by power supply two. Interconnection of two power supplies is avoided, but automatic switching cannot be achieved.

2. Realize power switching through contactors and relays, such as the patent titled "Automatic Switching Device for Internal and External Power Supply of Photovoltaic Grid-connected Inverters", the patent number is CN201220506549.4. The first power supply is powered by the first contact of the contactor, and the second power supply is powered by the second contact of the contactor. The control coil of the first contactor, one end of the normally closed auxiliary contact of the second contactor, and the normally closed contact of the relay are connected in series. The control coil, one end of the normally closed auxiliary contact of contactor 1, and the normally open contact of the relay are connected in series, and the other end of the normally closed auxiliary contact of contactor 1 is connected with the other end of the normally closed auxiliary contact of contactor 2. One end of the control power supply, the common contact of the relay is connected to the other end of the normal control power supply, and the control coil of the relay is powered by the second power supply, so as to realize the interlock of contactor 1 and contactor 2. When there is no power supply 2, contactor 1 pulls in, contactor 2 disconnects, power supply 1 supplies power to the power supply object through contactor 1 and the transformer; when there is power supply 2, the relay operates, the normally open contact pulls in, and the normally closed contact breaks Open, make contactor 2 pull in, contactor 1 is disconnected at the same time, power supply 2 supplies power to the power supply object through contactor 2 and the transformer. Since the interval between the contact actions of contactor 1 and contactor 2 is too short, an arc may be generated, and it is impossible to replace contactor 1 and contactor 2 with a relay, and this circuit needs to supply power to the power supply object through two transformers, the structure Complicated and expensive.

Contents of the invention

The purpose of the utility model is to provide a switching circuit which can realize automatic switching, has delay and avoids electric arc.

In order to achieve the above object, the technical solution of the present utility model is to provide an automatic switching circuit for a power supply system, which is characterized in that it includes a relay one with a normally closed contact, a relay two with a normally open contact and a delay control unit, One end of the normally closed contact of relay 1 and one end of the normally open contact of relay 2 are respectively connected to the power supply 1 and the selected power supply 2, the other end of the normally closed contact of relay 1 and the normally open contact of relay 2 The other end of the power supply is connected with the common power supply output terminal circuit, and the power supply 2 provides the working voltage for the delay control unit. The delay control unit includes a power-off delay control sub-circuit and a power-on delay control sub-circuit, and the power-off delay control sub-circuit The circuit and the power-on delay control sub-circuit respectively control the opening and closing of the normally closed contact of relay one and the normally open contact of relay two, wherein:

The power-off delay control sub-circuit outputs a control signal immediately after being energized, and the normally closed contact of the control relay 1 is disconnected. One outputs the control signal, after the preset time period one, the power-off delay control sub-circuit stops outputting the control signal, and the normally closed contact of relay one closes;

The power-on delay control sub-circuit outputs the control signal after delaying the preset time period 2 after being powered on, and the normally open contact of the control relay 2 is closed. After power-off, the power-on delay control sub-circuit immediately stops outputting the control signal, and the relay The normally open contact of the is open.

Preferably, the delay control unit further includes a control power supply, which converts the voltage provided by the second power supply into the working voltage of the power-off delay control sub-circuit and the power-on delay control sub-circuit.

Preferably, the other end of the normally closed contact of the relay 1 and the other end of the normally open contact of the relay 2 communicate with a common power supply output terminal circuit through a transformer.

Preferably, the secondary winding of the transformer communicates with the power supply output circuit;

The first power supply is _an AC power supply of a voltage V1, and the _second power supply is an AC power supply of a voltage V2, and the transformer has a primary winding _one with a number of turns of N1 and a _second primary winding with a number of turns of N2 , N ₁ >N ₂ , if the voltage V ₁ >voltage V ₂ , then the other end of the normally closed contact of the relay one is connected to the primary winding one, and the other end of the normally open contact of the relay two is connected to the primary winding For winding two, if the voltage V ₁ <voltage V ₂ , then the other end of the normally closed contact of the relay one is connected to the primary winding two, and the other end of the normally open contact of the relay two is connected to the primary winding one.

Preferably, the primary winding 1 and the primary winding 2 are formed by drawing a center tap from the primary winding of the transformer.

Preferably, the first primary winding and the second primary winding of the transformer are two isolated primary windings.

The beneficial effects of the utility model are: adopting two relays and a delay control unit, the structure is simple and the cost is low; when the power supply 2 is disconnected, it can automatically switch to the power supply 1, and when the power supply 2 is connected, it can automatically switch Power supply to power supply 2; switching from power supply 2 to power supply 1, and switching from power supply 1 to power supply 2 are all delayed, that is, when switching, the current power supply is automatically disconnected first, after a delay for a period of time, and then automatically connected Power supply to avoid arcing and cause interconnection of two power supplies.

Description of drawings

Fig. 1 is the schematic circuit diagram of embodiment 1 in the utility model;

Fig. 2 is the schematic circuit diagram of embodiment 2 in the utility model;

Fig. 3 is the schematic circuit diagram of embodiment 3 in the utility model;

Fig. 4 is the schematic circuit diagram of embodiment 4 in the utility model;

Fig. 5 is a specific circuit diagram for realizing the utility model.

detailed description

In order to make the utility model more comprehensible, preferred embodiments are described in detail below with accompanying drawings.

Example 1

As shown in Figure 1, a power supply system automatic switching circuit disclosed in this embodiment includes a relay 1, a relay 2, and a delay control unit 6, wherein the delay control unit 6 includes a control power supply 5, a power-off delay control sub-circuit 3 , Power-on delay control sub-circuit 4. The power-off delay control sub-circuit 3 can output control signals immediately after power-on, and can also output control signals within a period of time after power-off; the power-on delay control sub-circuit 4 must delay for a period of time after power-on. Output control signal, stop outputting control signal immediately after power failure.

Power supply 1 is connected to one end of the normally closed contact of relay 1, power supply 2 is connected to one end of the normally open contact of relay 2, and the other end of the normally closed contact of relay 1 is connected to the other end of the normally open contact of relay 2 as a power supply output . The power supply 2 supplies power to the delay control unit 6 , the power-off delay control sub-circuit 3 controls the relay 1 , and the power-on delay control sub-circuit 4 controls the relay 2 .

When the power supply 1 is connected and there is no power supply 2, the normally closed contact of relay 1 is closed, the normally open contact of relay 2 is disconnected, and the power supply 1 is powered by the normally closed contact of relay 1.

When the power supply 2 is connected, the power supply 2 supplies power to the delay control unit 6, and the power-off delay control sub-circuit 3 causes the normally closed contact of the relay 1 to be disconnected immediately, and the power supply stops when the power supply stops. After a period of time, the power-on delay control The sub-circuit 4 makes the normally open contact of the relay 2 close, and the power supply 2 supplies power through the normally open contact of the relay 2, realizing the delayed automatic switching from the power supply 1 to the power supply 2.

When the power supply 2 is disconnected, the delay control unit 6 is powered off, and the power-on delay control sub-circuit 4 makes the normally open contact of the relay 2 disconnect immediately, and the power supply 2 stops supplying power. After a period of time, the power-off delay control sub-circuit 3 Make the normally closed contact of relay 1 close, and power supply 1 is powered by the normally closed contact of relay 1, realizing the delayed automatic switching from power supply 2 to power supply 1.

Example 2

As shown in FIG. 2 , the difference between this embodiment and Embodiment 1 is that the control power supply 5 in the delay control unit 6 is omitted, so at this time, the second power supply meets the power supply requirements of the delay control unit 6 . Other structures and working principles are the same as in Embodiment 1.

When power supply 1 and power supply 2 are AC power supply and the voltages of power supply 1 and power supply 2 are different, the power supply output in Figure 1 can also be divided into two groups, which are respectively connected to different primary windings of transformer 7 and secondary windings of transformer 7 As a power supply output, the power supply with higher voltage is connected to the primary winding with more turns, and the power supply with lower voltage is connected to the primary winding with fewer turns. Embodiment 3 and Embodiment 4 are used for further description below.

Example 3

As shown in FIG. 3 , in this embodiment, the power source 1 and the power source 2 are both AC power sources, and the voltage of the power source 2 is higher than the voltage of the power source 1 at this time. The difference between this embodiment and Embodiment 1 is that a transformer 7 is added, the secondary winding of the transformer 7 is used as a power supply output, the primary winding of the transformer 7 contains a middle tap b, and one end of the power supply one output is connected to one end of the power supply two output , connected to the common tap o of the primary winding of the transformer 7, the other end of the power supply one output is connected to the middle tap b of the primary winding of the transformer 7, and the other end of the power supply two output is connected to the tap a of the primary winding of the transformer 7.

Other structures and working principles are the same as in Embodiment 1.

Example 4

As shown in Figure 4, the difference between this embodiment and Embodiment 3 is that the transformer 7 has two isolated primary windings, and the two ends of the output of the power supply 1 are respectively connected to the two ends b of the primary winding of the transformer 7 with fewer turns. , o2 are connected, and the two ends of the output of the power supply 2 are respectively connected with the two ends a and o1 of the primary winding of the transformer 7 with more turns. Other structures and working principles are the same as in Embodiment 3.

Example 5

A circuit of a specific embodiment of the present invention is as shown in Figure 5, it should be noted that those skilled in the art can design completely different circuits according to the above description, and this embodiment 5 is only to illustrate more clearly The utility model does not mean that each functional module of the utility model can only be realized by the following unique circuit form.

In this embodiment, the utility model includes a first relay K1, a second relay K2, and a delay control unit. The anode of the second Zener diode D2 is connected to the anode of the third diode D3, the cathode of the third diode D3 is connected to the positive pole of the control coil of the first relay K1, and the cathode of the second Zener diode D2 is connected to the first relay The negative pole of the control coil of K1 is connected to serve as the absorbing circuit of the control coil of the first relay K1 to limit the self-induced electromotive force generated when the control coil of the first relay K1 is powered off. The anode of the fifth zener diode D5 is connected to the anode of the sixth diode D6, the cathode of the sixth diode D6 is connected to the anode of the control coil of the second relay K2, and the cathode of the fifth zener diode D5 is connected to the second relay The negative pole of the control coil of K2 is connected to serve as the absorption circuit of the control coil of the second relay K2, which is used to limit the self-inductance electromotive force generated by the control coil of the second relay K2 when the power is cut off.

The delay control unit includes a control power supply, a power-off delay control sub-circuit, and a power-on delay control sub-circuit. The control power supply includes an AC/DC power supply module U1 and a fifth capacitor C5. The input terminal of the AC/DC power supply module U1 is connected to the second AC power supply POWER2 (POWER2_L, POWER2_N), the positive pole of the fifth capacitor C5 is connected to the output positive pole +VO of the AC/DC power supply module U1, and the negative pole of the fifth capacitor C5 is connected to AC/DC The output negative pole -VO of the power module U1 is used as a filter capacitor for controlling the power supply. The power-off delay control subcircuit includes a first diode D1, a first resistor R1, and a first capacitor C1. The anode of the first diode D1 is connected to the positive pole of the control power supply, the cathode of the first diode D1 is connected to the positive pole of the control coil of the first relay K1 through the first resistor R1, and the positive pole of the first capacitor C1 is connected to the first relay K1 control The positive pole of the coil and the negative pole of the first capacitor C1 are connected to the negative pole of the control power supply, and the negative pole of the control coil of the first relay K1 is connected to the negative pole of the control power supply. The power-on delay control subcircuit includes a second capacitor C2, a fourth diode D4, a second resistor R2, a third capacitor C3, a third resistor R3, a fourth resistor R4, a fourth capacitor C4, and a first MOSFET Q1. The positive pole of the second capacitor C2 is connected to the positive pole of the control power supply, and at the same time connected to the positive pole of the control coil of the second relay K2, the negative pole of the second capacitor C2 is connected to the negative pole of the control power supply, the fourth diode D4 is connected in parallel with the second resistor R2, and the fourth The cathode of the diode D4 is connected to the positive pole of the control power supply, the anode of the fourth diode D4 is connected to one end of the third capacitor C3, and at the same time connected to the gate of the first MOSFET Q1 through the third resistor R3, and the other end of the third capacitor C3 One end is connected to the negative pole of the control power supply, the fourth resistor R4 is connected in parallel with the fourth capacitor C4, and then connected in parallel to the gate and source of the first MOSFET Q1, the drain of the first MOSFET Q1 is connected to the negative pole of the K2 control coil, the first The source of the MOSFET Q1 is connected to the negative pole of the control power supply.

The first AC power supply POWER1 is connected to one end of the normally closed contact of the first relay K1, the second AC power supply POWER2 is connected to one end of the normally open contact of the second relay K2, and the other end of the normally closed contact of the first relay K1 is connected to the second relay K2 The other end of the normally open contact is connected as the power supply output end.

When the second AC power supply POWER2 has no electricity, the delay control unit also has no power supply, the normally closed contact of the first relay K1 is closed, the normally open contact of the second relay K2 is disconnected, and the first AC power supply POWER1 (POWER1_L, POWER1_N) Power supply POWER_OUT_L, POWER_OUT_N is output through the normally closed contact of the first relay K1.

When the second AC power supply POWER2 starts to have power, the control power supply starts to output normally, the control coil of the first relay K1 is energized, the normally closed contact of the first relay K1 is immediately disconnected, the first AC power supply POWER1 stops supplying power, and at the same time, the control power supply Start to charge the third capacitor C3 through the second resistor R2, the voltage across the third capacitor C3 starts to rise from zero, and the gate-source voltage VGS of the first MOSFET Q1 also starts to rise from zero. After a period of time, when VGS When it rises to the turn-on threshold voltage VGS(TH) of the first MOSFET tube Q1, the first MOSFET tube Q1 is turned on, the control coil of the second relay K2 is energized, the normally open contact of the second relay K2 is closed, and the second AC power supply POWER2 passes through the second The normally open contacts of the second relay K2 output power supplies POWER_OUT_L and POWER_OUT_N, realizing the delayed automatic switching from the first AC power source POWER1 to the second AC power source POWER2.

When the second AC power supply POWER2 starts to lose power, the voltage of the control power supply drops rapidly, and the voltage at both ends of the control coil of the second relay K2 drops rapidly. At the same time, the third capacitor C3 discharges rapidly through the fourth diode D4, and the third capacitor C3 The terminal voltage drops rapidly, the gate-source voltage VGS of the first MOSFET Q1 also drops rapidly below the turn-on threshold voltage VGS(TH) of the first MOSFET Q1, the first MOSFET Q1 is quickly turned off, and the second relay K2 controls the coil Power failure, the normally open contact of the second relay K2 is disconnected, and the second AC power supply POWER2 stops supplying power. The large capacity of the first capacitor C1 and the blocking function of the first diode D1 make it possible to control the power supply voltage after a rapid drop. The voltage at both ends of the control coil of the first relay K1 can be maintained above the contact release voltage for a period of time. During this period of time, the normally closed contact of the first relay K1 maintains an open state. The terminal voltage drops to the contact release voltage, the normally closed contact of the first relay K1 is closed, and the first AC power supply POWER1 outputs power supply POWER_OUT_L and POWER_OUT_N through the normally closed contact of the first relay K1, realizing the transfer from the second AC power supply POWER2 to the first Delayed automatic switching of AC power supply POWER1.

Claims (6)

1. a power-supply system automatic switch-over circuit, it is characterised in that include band normally-closed contact relay one (1), Relay two (2) with normally opened contact and delays time to control unit (6), the normally-closed contact of relay one (1) One end, relay two (2) normally opened contact one end respectively with power supply one and select access power supply two be connected, The other end of normally-closed contact of relay one (1), relay two (2) the other end of normally opened contact with common Power supply circuit of output terminal communicate, by power supply two be delays time to control unit (6) provide running voltage, time delay control Unit processed (6) includes that power cut off delay controls electronic circuit (3) and on-delay controls electronic circuit (4), and power-off is prolonged Time control system circuit (3) and on-delay control electronic circuit (4) and control the normally closed of relay one (1) respectively The normally opened contact of contact and relay two (2) disconnects and Guan Bi, wherein:

Power cut off delay control electronic circuit (3) electric after export control signal immediately, control relay one (1) Normally-closed contact disconnect, after a loss of power, power cut off delay control electronic circuit (3) in preset time period one, protect Holding and export control signal to relay one (1), after preset time period one, power cut off delay controls electronic circuit (3) Stop output control signal, the normally-closed contact Guan Bi of relay one (1)；

On-delay control electronic circuit (4) electric after postpone to export after preset time period two control signal, control The normally opened contact Guan Bi of relay two (2) processed, after a loss of power, on-delay controls electronic circuit (4) and stops immediately Only exporting control signal, the normally opened contact of relay two (2) disconnects.

2. a kind of power-supply system automatic switch-over circuit as claimed in claim 1, it is characterised in that described time delay control Unit processed (6) also includes controlling power supply (5), is turned by the voltage that described power supply two provides by controlling power supply (5) It is changed to described power cut off delay and controls electronic circuit (3) and the running voltage of described on-delay control electronic circuit (4).

3. a kind of power-supply system automatic switch-over circuit as claimed in claim 1, it is characterised in that described relay The other end of the other end of the normally-closed contact of (1) and the normally opened contact of described relay two (2) is via transformation Device (7) communicates with common power supply circuit of output terminal.

4. a kind of power-supply system automatic switch-over circuit as claimed in claim 3, it is characterised in that described transformator (7) vice-side winding communicates with described power supply circuit of output terminal；

Described power supply one is voltage V₁Alternating current power supply, described power supply two is voltage V₂Alternating current power supply, then institute State transformator (7) having the number of turn is N₁Primary side winding one and the number of turn be N₂Primary side winding two, N₁＞ N₂, If voltage V₁＞ voltage V₂, the other end of the normally-closed contact of the most described relay one (1) connects primary side winding one, The other end of the normally opened contact of described relay two (2) connects primary side winding two, if voltage V₁＜ voltage V₂, The other end of the normally-closed contact of the most described relay one (1) connects primary side winding two, described relay two (2) Normally opened contact the other end connect primary side winding one.

5. a kind of power-supply system automatic switch-over circuit as claimed in claim 4, it is characterised in that by described The primary side winding of transformator (7) is drawn centre tap thus is formed described primary side winding one and described primary side winding Two.

6. a kind of power-supply system automatic switch-over circuit as claimed in claim 4, it is characterised in that described transformator (7) primary side winding one and primary side winding two are two primary side winding isolated.