A relay driving circuit, a three-phase rectifying circuit and an air conditioner

Abstract

The utility model provides a relay drive circuit, three -phase rectifier circuit and air conditioner belong to relay technical field for controlling air conditioner three -phase rectifier circuit in first relay K1, second relay K2 and third relay K3, wherein: first relay K1 and first pre -charge current -limiting resistance R1, second pre -charge current -limiting resistance R2 are connected in series after, and the both ends of third relay K3 are connected in parallel, the output end of rectifier bridge connects direct current bus, the drive circuit includes: first drive subcircuit, its input end connects direct current bus voltage sampling signal, and its output end is connected to third relay K3 and the control end of second relay K2 simultaneously, second drive subcircuit, its input end connects direct current bus voltage sampling signal and reference voltage signal, and its output end is connected to the control end of first relay K1. The utility model has solved the problem of overcurrent burnout caused by pre -charge resistance in air conditioner three -phase rectifier system due to relay fault.

Description

Technical Field

[0001] This utility model belongs to the field of relay technology, and more specifically, relates to a relay drive circuit, a three-phase rectifier circuit, and an air conditioner. Background Technology

[0002] In the three-phase rectifier system of commercial air conditioners, the reliable control of relays is directly related to the safety and energy efficiency of the entire unit.

[0003] The prior art document (CN107946138A) discloses a method for improving the service life of a relay in a safety control circuit, belonging to the field of safety circuit technology. It adds an electronic switch in series in the safety output circuit and controls the operation sequence of the relay contacts and the electronic switch. That is, when the safety output is activated, the relay contacts are closed first and then the electronic switch is closed. When the safety is turned off, the electronic switch is opened first and then the relay contacts are opened. However, it only considers the service life of the relay and has the disadvantage of requiring two independent control circuits for the electronic switch and the relay. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this utility model provides a relay drive circuit, a three-phase rectifier circuit, and an air conditioner.

[0005] The present invention adopts the following technical solution.

[0006] This utility model provides a relay drive circuit in its first aspect for controlling a first relay K1, a second relay K2, and a third relay K3 in a three-phase rectifier circuit of an air conditioner, wherein:

[0007] The first relay K1 is connected in series with the first pre-charge current limiting resistor R1 and the second pre-charge current limiting resistor R2, and then connected in parallel across the three relays K3.

[0008] The third relay K3 is connected between the first phase L1 of the three-phase power supply and the input terminal of the rectifier bridge, and the second relay K2 is connected between the second phase L2 of the three-phase power supply and the input terminal of the rectifier bridge.

[0009] The output end of the rectifier bridge is connected to the DC bus.

[0010] The driving circuit includes:

[0011] The first driving sub-circuit has its input terminal connected to the DC bus voltage sampling signal, and its output terminal connected to the control terminals of the third relay K3 and the second relay K2, for controlling the third relay K3 and the second relay K2 to be turned on or off synchronously.

[0012] The second driving sub-circuit has its input terminal connected to the DC bus voltage sampling signal and the reference voltage signal, and its output terminal connected to the control terminal of the first relay K1. It is used to control the opening or closing of the first relay K1 based on the comparison result between the DC bus voltage sampling signal and the reference voltage signal.

[0013] Optionally, the first driving sub-circuit includes:

[0014] The processor chip has its input terminal connected to the DC bus voltage sampling signal;

[0015] The switching transistor Q1 has its control terminal connected to the output terminal of the processor chip, and its output terminal serves as the output terminal of the first driving sub-circuit, while also being connected to the control terminals of the third relay K3 and the second relay K2.

[0016] Optionally, the second driving sub-circuit includes:

[0017] Comparator U has its non-inverting input connected to the DC bus voltage sampling signal and its inverting input connected to the reference voltage signal.

[0018] The logic gate circuit U1 has its first input terminal connected to the power-on high-level signal of the main control chip, and its second input terminal connected to the output terminal of the comparator U.

[0019] The switching transistor Q2 has its control terminal connected to the output terminal of the logic gate circuit U1, and its output terminal is connected to the control terminal of the first relay K1 as the output terminal of the second driving sub-circuit.

[0020] Optionally, the logic gate circuit U1 is a NAND gate.

[0021] A second aspect of this utility model provides a three-phase rectifier circuit, comprising the relay drive circuit described in the first aspect of this utility model, the circuit further comprising:

[0022] Three-phase input power supply;

[0023] The rectifier bridge has its input terminals connected to the three-phase input power supply.

[0024] The charging circuit, connected to the output terminal of the rectifier bridge, includes an energy storage capacitor and a voltage divider resistor;

[0025] The sampling circuit, connected in parallel across the charging circuit, consists of a first sampling resistor Rc1 and a second sampling resistor Rc2 connected in series, and is used to output the bus voltage sampling signal.

[0026] Optionally, the charging circuit includes:

[0027] Diode D, whose anode is connected to the first output terminal of the rectifier bridge;

[0028] The ninth voltage divider resistor R9 has one end connected to the cathode of the diode D;

[0029] The first energy storage capacitor C1 and the second energy storage capacitor C2 are connected in series between the other end of the ninth voltage divider resistor R9 and the second output terminal of the rectifier bridge.

[0030] The third voltage divider resistor R3, the third voltage divider resistor R4 and the fifth voltage divider resistor R5 are connected in series and in parallel across the first energy storage capacitor C1.

[0031] The sixth voltage divider resistor R6, the seventh voltage divider resistor R7, and the eighth voltage divider resistor R8 are connected in series and in parallel across the second energy storage capacitor C2.

[0032] The third aspect of this utility model provides an air conditioner, including the three-phase rectifier circuit described in the second aspect of this utility model.

[0033] Compared with the prior art, the beneficial effects of this utility model include at least the following: solving the problem of resistors in the main control circuit burning out due to overcurrent. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of a low-power dynamic control circuit provided according to an embodiment of the present utility model;

[0035] Figure 2 This is a schematic diagram of a conventional low-power control circuit provided according to an embodiment of the present invention. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this utility model clearer, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. The described embodiments are merely some embodiments of this utility model, not all embodiments. Based on the spirit of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0037] In Embodiment 1, this utility model provides a relay driving circuit for controlling the first relay K1, the second relay K2, and the third relay K3 in a three-phase rectifier circuit of an air conditioner, wherein:

[0038] The first relay K1 is connected in series with the first pre-charge current limiting resistor R1 and the second pre-charge current limiting resistor R2, and then connected in parallel across the three relays K3.

[0039] The third relay K3 is connected between the first phase L1 of the three-phase power supply and the input terminal of the rectifier bridge, and the second relay K2 is connected between the second phase L2 of the three-phase power supply and the input terminal of the rectifier bridge.

[0040] The output end of the rectifier bridge is connected to the DC bus.

[0041] The driving circuit includes:

[0042] The first driving sub-circuit has its input terminal connected to the DC bus voltage sampling signal, and its output terminal connected to the control terminals of the third relay K3 and the second relay K2, for controlling the third relay K3 and the second relay K2 to be turned on or off synchronously.

[0043] The second driving sub-circuit has its input terminal connected to the DC bus voltage sampling signal and the reference voltage signal, and its output terminal connected to the control terminal of the first relay K1. It is used to control the opening or closing of the first relay K1 based on the comparison result between the DC bus voltage sampling signal and the reference voltage signal.

[0044] Preferably, the first driving sub-circuit includes:

[0045] The processor chip has its input terminal connected to the DC bus voltage sampling signal;

[0046] The switching transistor Q1 has its control terminal connected to the output terminal of the processor chip, and its output terminal serves as the output terminal of the first driving sub-circuit, while also being connected to the control terminals of the third relay K3 and the second relay K2.

[0047] Preferably, the second driving sub-circuit includes:

[0048] Comparator U has its non-inverting input connected to the DC bus voltage sampling signal and its inverting input connected to the reference voltage signal.

[0049] The logic gate circuit U1 has its first input terminal connected to the power-on high-level signal of the main control chip, and its second input terminal connected to the output terminal of the comparator U.

[0050] The switching transistor Q2 has its control terminal connected to the output terminal of the logic gate circuit U1, and its output terminal is connected to the control terminal of the first relay K1 as the output terminal of the second driving sub-circuit.

[0051] More preferably, the main control chip maintains a high-level output when the circuit is powered on.

[0052] More preferably, the switching transistor includes an IGBT transistor.

[0053] Preferably, the logic gate circuit U1 is a NAND gate.

[0054] In Embodiment 2, this utility model provides a three-phase rectifier circuit, which includes the relay drive circuit described in Embodiment 1. The circuit further includes:

[0055] Three-phase input power supply;

[0056] The rectifier bridge has its input terminals connected to the three-phase input power supply.

[0057] The charging circuit, connected to the output terminal of the rectifier bridge, includes an energy storage capacitor and a voltage divider resistor;

[0058] The sampling circuit, connected in parallel across the charging circuit, consists of a first sampling resistor Rc1 and a second sampling resistor Rc2 connected in series, and is used to output the bus voltage sampling signal.

[0059] More preferably, the voltage at the connection point of the first sampling resistor Rc1 and the second sampling resistor Rc2 is used as the bus voltage sampling signal.

[0060] Preferably, the charging circuit includes:

[0061] Diode D, whose anode is connected to the first output terminal of the rectifier bridge;

[0062] The ninth voltage divider resistor R9 has one end connected to the cathode of the diode D;

[0063] The first energy storage capacitor C1 and the second energy storage capacitor C2 are connected in series between the other end of the ninth voltage divider resistor R9 and the second output terminal of the rectifier bridge.

[0064] The third voltage divider resistor R3, the third voltage divider resistor R4 and the fifth voltage divider resistor R5 are connected in series and in parallel across the first energy storage capacitor C1.

[0065] The sixth voltage divider resistor R6, the seventh voltage divider resistor R7, and the eighth voltage divider resistor R8 are connected in series and in parallel across the second energy storage capacitor C2.

[0066] It should be noted that when the DC bus voltage sampling signal is less than the reference voltage signal:

[0067] The second driving sub-circuit outputs a high-level driving signal to turn on the first relay K1;

[0068] The first driver circuit outputs a low-level drive signal to turn off the second relay K2 and the third relay K3;

[0069] Current path: Phase 1 L1→R1→R2→K1→rectifier bridge; Phase 3 L3 is directly connected to the rectifier bridge;

[0070] A two-phase pre-charge circuit is formed;

[0071] When the DC bus voltage sampling signal is not less than the reference voltage signal:

[0072] The second driving sub-circuit outputs a low-level driving signal to turn off the first relay K1.

[0073] The first driving sub-circuit outputs a high-level driving signal, causing the second relay K2 and the third relay K3 to conduct simultaneously.

[0074] Current path: Phase 1 L1 → K3 → rectifier bridge; Phase 2 L2 → K2 → rectifier bridge; Phase 3 L3 directly connected to the rectifier bridge;

[0075] The three phases are powered together.

[0076] In Embodiment 3, this utility model provides an air conditioner, which includes a three-phase rectifier circuit as described in Embodiment 2.

[0077] The technical solution provided by this utility model simplifies the circuit structure, accelerates the response of the main control circuit, and effectively solves the problem of the main control circuit resistor burning out due to overcurrent by directly controlling the relay with a logic switch.

[0078] In Example 4, as Figure 1 As shown, this utility model proposes a low-power dynamic control circuit, which consists of resistors R1~R9, capacitors C1 and C2, first~third relays K1~K3, comparator U, NAND gate U1, DSP chip, and main control signal. Its working principle is as follows:

[0079] The sampling circuit consists of R c1 ~R c2 The circuit consists of a sampling circuit that collects the bus voltage sampling signal, which is then input to the DSP and comparator U for processing.

[0080] The non-inverting input of comparator U is connected to the bus voltage sampling signal, and the inverting input is connected to the reference voltage value.

[0081] Upon power-on, the main control board sends a main control signal to the NAND gate U1. At this time, the bus voltage sampled by the sampling circuit is lower than the set reference voltage, so the comparator U outputs a low level and the NAND gate U1 outputs a high level. The coil of the first relay K1 is energized, the contacts close, and the first relay K1 is turned on. The charging circuit consists of the first relay K1, resistors R1~R9, diode D, and capacitors C1 and C2.

[0082] When the bus voltage sampled by the sampling circuit is higher than the reference voltage, comparator U outputs a high level and NAND gate U1 outputs a low level, turning off the first relay K1. At this time, the charging circuit consists of the third relay K3, resistors R3~R9, diode D, and capacitors C1 and C2. Even if the DSP chip on the driver board fails and outputs a control signal that turns off the third relay K3, because the bus voltage is still higher than the reference voltage, comparator U still outputs a high level and NAND gate U1 still outputs a low level, keeping the first relay K1 in the off state and protecting resistors R1 and R2.

[0083] In comparison, a conventional low-power control circuit consists of R1, R2, K1, K2, Q1, Q2, a DSP, and a main controller, such as... Figure 2 As shown, the working principle is as follows:

[0084] When powered on, the air conditioner main control board is powered on and sends a main control signal to relay K1. At this time, relay K1 is energized and conducts. The charging circuit on the drive board consists of relay K1, resistors R1~R9, diode D, and capacitors C1 and C2. Capacitors C1 and C2 begin to charge.

[0085] The sampling circuit consists of R c1 ~R c2 The circuit consists of a DSP that controls relay K0 to turn on or off based on the bus voltage sampling signal acquired by the sampling circuit. When the bus voltage sampling signal is lower than the bus voltage reference sampling signal, the DSP sends a low-level control signal, and K0 is in the off state. The charging circuit consists of relay K1, resistors R1~R9, diode D, and capacitors C1 and C2. When the bus voltage sampling signal is higher than the bus voltage reference sampling signal, the DSP sends a high-level control signal, IGBT Q1 is turned on, the coil of relay K0 is energized, the contacts are closed, and K0 is in the on state. At this time, relay K1 and resistors R1 and R2 are short-circuited by relay K0, and the charging circuit consists of relay K0, resistors R3~R9, diode D, and capacitors C1 and C2.

[0086] When relay K0 is turned on, relay K1, resistors R1 and R2 are short-circuited by relay K0. If the main controller is unable to send a control signal to turn off relay K1 due to a fault, K1 will always be in the on state. When the DSP chip on the driver board suddenly turns off relay K0 due to a fault, a large current will flow through relay K1, resistors R1 and R2, causing resistors R1 and R2 to be damaged by overcurrent.

[0087] Technical problems existing in conventional low-power control circuits include: branch overcurrent problems caused by abnormal relay disconnection, insufficient response speed of traditional protection schemes, and lack of dynamic collaborative control mechanisms. In order to address the shortcomings of existing technologies, this utility model proposes a three-phase input power supply relay dynamic shutdown circuit, which solves the problem of overcurrent burnout caused by the relay on the three-phase power supply line suddenly disconnecting after being energized, while the relay on the low-power branch remains energized.

[0088] Figure 1 The low-power dynamic control circuit consists of: R1 and R2 as pre-charge current-limiting resistors, R3~R9 as voltage divider resistors, and R... c1 ~R c2 K1~K3 are sampling resistors, D is a diode, C1 and C2 are energy storage capacitors, Q1~Q2 are IGBTs, U is a comparator, and U1 is a NAND gate.

[0089] Figure 2 The typical low-power control circuit consists of: R1 and R2 as pre-charge current-limiting resistors, R3~R9 as voltage divider resistors, and R... c1 ~R c2 K is the sampling resistor, K0~K2 are relays, D is a diode, C1 and C2 are energy storage capacitors, and Q1~Q2 are IGBTs.

[0090] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of this utility model and not to limit it. Although the utility model has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of this utility model. Any modifications or equivalent substitutions that do not depart from the spirit and scope of this utility model should be covered within the protection scope of the claims of this utility model.

Claims

1. A relay drive circuit, characterized in that, The first relay K1, the second relay K2, and the third relay K3 are used to control the three-phase rectifier circuit of the air conditioner, wherein: The first relay K1 is connected in series with the first pre-charge current limiting resistor R1 and the second pre-charge current limiting resistor R2, and then connected in parallel across the three relays K3. The third relay K3 is connected between the first phase L1 of the three-phase power supply and the input terminal of the rectifier bridge, and the second relay K2 is connected between the second phase L2 of the three-phase power supply and the input terminal of the rectifier bridge. The output end of the rectifier bridge is connected to the DC bus. The driving circuit includes: The first driving sub-circuit has its input terminal connected to the DC bus voltage sampling signal, and its output terminal connected to the control terminals of the third relay K3 and the second relay K2, for controlling the third relay K3 and the second relay K2 to be turned on or off synchronously. The second driving sub-circuit has its input terminal connected to the DC bus voltage sampling signal and the reference voltage signal, and its output terminal connected to the control terminal of the first relay K1. It is used to control the opening or closing of the first relay K1 based on the comparison result between the DC bus voltage sampling signal and the reference voltage signal.

2. The relay drive circuit according to claim 1, characterized in that: The first driving sub-circuit includes: The processor chip has its input terminal connected to the DC bus voltage sampling signal; The switching transistor Q1 has its control terminal connected to the output terminal of the processor chip, and its output terminal serves as the output terminal of the first driving sub-circuit, while also being connected to the control terminals of the third relay K3 and the second relay K2.

3. A relay driving circuit according to claim 1, characterized in that: The second driving sub-circuit includes: Comparator U has its non-inverting input connected to the DC bus voltage sampling signal and its inverting input connected to the reference voltage signal. The logic gate circuit U1 has its first input terminal connected to the power-on high-level signal of the main control chip, and its second input terminal connected to the output terminal of the comparator U. The switching transistor Q2 has its control terminal connected to the output terminal of the logic gate circuit U1, and its output terminal is connected to the control terminal of the first relay K1 as the output terminal of the second driving sub-circuit.

4. A relay driving circuit according to claim 3, characterized in that: The logic gate circuit U1 is a NAND gate.

5. A three-phase rectifier circuit, comprising a relay drive circuit as described in any one of claims 1-4, characterized in that, The circuit also includes: Three-phase input power supply; The rectifier bridge has its input terminals connected to the three-phase input power supply. The charging circuit, connected to the output terminal of the rectifier bridge, includes an energy storage capacitor and a voltage divider resistor; The sampling circuit, connected in parallel across the charging circuit, consists of a first sampling resistor Rc1 and a second sampling resistor Rc2 connected in series, and is used to output the bus voltage sampling signal.

6. A three-phase rectifier circuit according to claim 5, characterized in that: The charging circuit includes: Diode D, whose anode is connected to the first output terminal of the rectifier bridge; The ninth voltage divider resistor R9 has one end connected to the cathode of the diode D; The first energy storage capacitor C1 and the second energy storage capacitor C2 are connected in series between the other end of the ninth voltage divider resistor R9 and the second output terminal of the rectifier bridge. The third voltage divider resistor R3, the third voltage divider resistor R4 and the fifth voltage divider resistor R5 are connected in series and in parallel across the first energy storage capacitor C1. The sixth voltage divider resistor R6, the seventh voltage divider resistor R7, and the eighth voltage divider resistor R8 are connected in series and in parallel across the second energy storage capacitor C2.

7. An air conditioner, characterized in that, Includes a three-phase rectifier circuit as described in claim 5 or 6.

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