Power input circuit and air conditioner

Abstract

The utility model discloses a power input circuit and an air conditioner, and belongs to the technical field of air conditioners. The power input circuit includes: a main power loop; the first switch unit is arranged in the main power supply loop; the auxiliary power supply loop comprises a step-down circuit and a switching power supply circuit which are connected in series; the detection circuit is connected with the auxiliary power supply loop and is configured to provide a voltage detection signal; and the control unit is connected with the first switch unit and the detection circuit, and is configured to receive the voltage detection signal and control the first switch unit to switch on or switch off the main power supply loop. The voltage grade of the power supply is judged before the main power supply loop is connected to the power supply, the switch unit of the main power supply loop is controlled to be switched on or switched off according to the detection result of the power supply, and the overvoltage fault risk of equipment is reduced.

Description

Technical Field

[0001] This application belongs to the field of air conditioning technology, and in particular relates to a power input circuit and an air conditioner. Background Technology

[0002] When electrical equipment is connected to a power source, if the voltage level of the power source exceeds the rated voltage of the equipment, it can easily lead to overvoltage faults, such as electrolytic capacitor explosions and power device overvoltage breakdowns. Utility Model Content

[0003] This application aims to at least solve one of the technical problems existing in the prior art. To this end, this application proposes a power input circuit and an air conditioner that determines the voltage level of the power supply before connecting the main power circuit, and controls the switching unit of the main power circuit to turn on or off based on the power supply detection result, thereby reducing the risk of equipment overvoltage failure.

[0004] In a first aspect, this application provides a power input circuit, characterized in that it includes:

[0005] The main power supply circuit has its input side connected to the power input node and its output side connected to the load.

[0006] The first switching unit is located in the main power supply circuit;

[0007] The auxiliary power supply circuit includes a series-connected step-down circuit and a switching power supply circuit. The input side of the step-down circuit is connected to the power input node, and the output side of the switching power supply circuit is used to provide auxiliary power.

[0008] The detection circuit is connected to the auxiliary power supply circuit and is configured to provide a voltage detection signal;

[0009] The control unit is connected to the first switching unit and the detection circuit, and is configured to receive voltage detection signals and control the first switching unit to turn on or off the main power supply circuit.

[0010] According to one embodiment of this application, the auxiliary power supply circuit further includes:

[0011] The second switching unit has its first terminal connected to the input side of the step-down circuit and its second terminal connected to the output side of the step-down circuit.

[0012] The control unit is also connected to the second switching unit and configured to control the second switching unit to be turned on or off.

[0013] According to one embodiment of this application, the auxiliary power supply circuit further includes:

[0014] The first rectifier circuit has its AC side connected to the output side of the step-down circuit, and its output side is connected to the input side of the switching power supply circuit.

[0015] According to one embodiment of this application, the detection circuit includes:

[0016] The voltage divider sampling unit is connected between the positive and negative DC lines on the output side of the first rectifier circuit and is connected to the control unit. The voltage divider sampling unit is configured to perform voltage divider sampling on the voltage between the positive and negative DC lines to provide a voltage detection signal.

[0017] According to one embodiment of this application, the main power supply circuit includes:

[0018] The second rectifier unit has its AC side connected to the first terminal of the first switching unit, and the second terminal of the first switching unit is connected to the power input node.

[0019] The power module has its input side connected to the DC side of the second rectifier unit and its output side connected to the load.

[0020] According to one embodiment of this application, the power input node includes three-phase lines, and the first switching unit includes a loop switch, a slow-start switch, and a slow-start resistor. At least two phase lines are provided with loop switches, and the slow-start switch and the slow-start resistor are connected in series and then connected in parallel with one of the loop switches.

[0021] According to one embodiment of this application, the main power supply circuit includes:

[0022] The second rectifier unit has its AC side connected to the power input node and its DC side connected to the first terminal of the first switching unit.

[0023] The power module has its input side connected to the second end of the first switching unit and its output side connected to the load.

[0024] According to one embodiment of this application, the first switching unit includes:

[0025] The circuit switch is located on the positive DC line on the DC side of the second rectifier unit;

[0026] A series-connected soft-start switch and soft-start resistor, which are then connected in parallel with the loop switch.

[0027] According to one embodiment of this application, the voltage level range of the power input node includes 220V and 380V.

[0028] Secondly, this application provides an air conditioner that includes the power input circuit as described above.

[0029] According to the power input circuit and air conditioner of this application, the step-down circuit can reduce the power supply connected to the power input node to a safe voltage range before supplying power to the switching power supply, so that the low-voltage components of the equipment can work normally. By detecting the voltage of the auxiliary power supply circuit, the voltage level of the power supply can be identified, and it can be determined whether the power supply is abnormal. This allows the first switching unit on the main power supply circuit to be turned on or off, thereby determining the voltage level of the power supply before the main power supply circuit is connected to the power supply, reducing the risk of overvoltage faults in the equipment.

[0030] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0031] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0032] Figure 1 This is one of the structural schematic diagrams of the power input circuit provided in the embodiments of this application;

[0033] Figure 2 This is a second schematic diagram of the power input circuit provided in the embodiments of this application;

[0034] Figure 3 This is one of the structural schematic diagrams of the first switching unit provided in the embodiments of this application;

[0035] Figure 4 This is the third schematic diagram of the power input circuit provided in the embodiments of this application;

[0036] Figure 5 This is the second schematic diagram of the structure of the first switching unit provided in the embodiments of this application.

[0037] Figure label:

[0038] The main power supply circuit 100, the first switching unit 110, the second rectifier unit 120, the power module 130, the auxiliary power supply circuit 200, the step-down circuit 210, the switching power supply circuit 220, the second switching unit 230, the first rectifier circuit 240, the detection circuit 300, the control unit 400, the load 500, and the fault indication unit 600. Detailed Implementation

[0039] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0040] In the following description, a "circuit" refers to a conductive loop consisting of at least one element or sub-circuit connected by an electrical or electromagnetic link. When an element or circuit is said to be "coupled to" or "connected to" another element, or when an element / circuit is said to be "coupled at" or "connected at" two nodes, it can be directly coupled to or connected to the other element, or there may be intermediate elements. The connection between elements can be physical, logical, or a combination thereof. Conversely, when an element is said to be "directly coupled to" or "directly connected to" another element, it means that there are no intermediate elements between them.

[0041] In the description, the terms "first," "second," etc., are used to distinguish similar objects, not to describe a specific order or sequence. It should be understood that such numerical descriptors can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class, not limited in number; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0042] Furthermore, the use of terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicates that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0043] Taking three-phase power systems as an example, voltage standards differ in different regions. For instance, there are 220V three-phase systems and 380V three-phase systems. A 220V three-phase system refers to a line voltage of 220V and a phase voltage of 127V. A 380V three-phase system refers to a line voltage of 380V and a phase voltage of 220V. The rated voltage of equipment is only compatible with one of these voltage levels of a three-phase system.

[0044] Taking an air conditioning system with a rated voltage of 220V three-phase power as an example, if the air conditioning system is mistakenly connected to a 380V three-phase power grid, the phase voltage will rise sharply from 127V to 220V, and the DC bus voltage will rise sharply from more than 300 volts to more than 500 volts, far exceeding the withstand voltage of the components (for example, the withstand voltage of electrolytic capacitors is usually 450V), which can easily lead to faults such as electrolytic capacitor explosion and overvoltage breakdown of power devices.

[0045] One embodiment of this application proposes a power input circuit and an air conditioner. The step-down circuit can reduce the power supply connected to the power input node to a safe voltage range before supplying power to the switching power supply, enabling the low-voltage components of the equipment to operate normally. By detecting the voltage of the auxiliary power supply circuit, the voltage level of the power supply can be identified, and it can be determined whether the power supply is abnormal. This allows the first switching unit on the main power supply circuit to be turned on or off. Thus, the voltage level of the power supply is determined before the main power supply circuit is connected to the power supply, reducing the risk of overvoltage faults in the equipment.

[0046] Reference Figure 1 , Figure 1 The structure of a power input circuit is shown, and one embodiment of this application proposes a power input circuit. In this embodiment, the power input circuit includes a main power circuit 100, a first switching unit 110, an auxiliary power circuit 200, a detection circuit 300, and a control unit 400. The input side of the main power circuit 100 is connected to a power input node, and the output side of the main power circuit 100 is connected to a load 500. The first switching unit 110 is disposed in the main power circuit 100. The auxiliary power circuit 200 includes a step-down circuit 210 and a switching power supply circuit 220 connected in series. The input side of the step-down circuit 210 is connected to the power input node, and the output side of the switching power supply circuit 220 is used to provide auxiliary power. The detection circuit 300 is connected to the auxiliary power circuit 200 and configured to provide a voltage detection signal. The control unit 400 is connected to the first switching unit 110 and the detection circuit 300 and configured to receive the voltage detection signal and control the first switching unit 110 to turn on or off the main power circuit 100.

[0047] The power input node is used to connect to an external power source, which can be the power grid or similar sources, and its voltage level may be 220V or 380V. Of course, the external power source can also be a power supply device, and this implementation does not limit this.

[0048] The main power circuit 100 is used to transmit electrical energy and supply power to the load 500. Taking the power input circuit applied to an air conditioner as an example, the load 500 can be a compressor motor. The first switching unit 110 has two states: on and off. When it is on, the main power circuit 100 can transmit electrical energy normally, and the load 500 is energized; when it is off, the main power circuit 100 is disconnected, and the load 500 is not energized.

[0049] The auxiliary power supply circuit 200 is used to obtain electrical energy from an external power source and provide auxiliary power to low-voltage components within the equipment, such as the control unit 400, chips, or indicator lights, through voltage conversion. The voltage of the auxiliary power supply can be 24V, 12V, 5V, or 3.3V, etc.

[0050] In this embodiment, the step-down circuit 210 first steps down the external power supply, and then the switching power supply circuit 220 converts the stepped-down voltage. The auxiliary power supply circuit 200 uses a two-stage voltage conversion between the step-down circuit 210 and the switching power supply circuit 220. The variation range of the external power supply voltage level is also reduced after being stepped down by the step-down circuit 210, and the switching power supply circuit 220 can work normally, thereby ensuring the supply of auxiliary power.

[0051] It should be noted that within the voltage level range of the power input node, the output voltage range of the buck circuit 210 is within the operating voltage range of the switching power supply circuit 220.

[0052] As an example, the target voltage range includes 220V and 380V. The step-down circuit 210 may include a transformer with a turns ratio of 1.5:1. Therefore, if the external power supply voltage is 220V, the output voltage of the step-down circuit 210 will be 146V. If a 380V external power supply is mistakenly connected, the output voltage of the step-down circuit 210 will be 253V. The voltage range of 146V to 253V is within the operating voltage range of the switching power supply circuit 220, meeting the normal operating requirements of the switching power supply circuit 220.

[0053] Compared to the external power supply voltage range of 380V-220V=160V, the output voltage range of the step-down circuit 210 is 253V-146V=107V, which is smaller and more likely to meet the input requirements of the switching power supply circuit 220. This ensures the normal operation of the switching power supply circuit 220 and also guarantees the normal operation of the subsequent voltage detection function.

[0054] The detection node of the detection circuit 300 can be set on the input side of the buck circuit 210, the output side of the buck circuit 210, or the input side of the switching power supply circuit 220. The control unit 400 receives the voltage detection signal, determines the voltage corresponding to the detection node, and then determines the voltage of the external power supply connected to the power input node.

[0055] As an example, the detection node is connected to the output side of the buck circuit 210, and the control unit 400 calculates the voltage of the external power supply based on the detected voltage and the buck ratio of the buck circuit 210. Assuming the buck ratio of the buck circuit 210 is 1.5:1, if the voltage of the detection node is 146V, the voltage of the external power supply is 220V; if the voltage of the detection node is 253V, the voltage of the external power supply is 380V.

[0056] The control unit 400 may be implemented using an MCU (Microcontroller Unit) chip; it may also be implemented using a DSP (Digital Signal Processor) chip, an FPGA (Field-Programmable Gate Array) chip, or a custom controller chip; the embodiments of this application do not limit the specific hardware implementation of the controller.

[0057] The control unit 400 compares the determined voltage of the external power supply with a preset safety threshold. If the voltage of the external power supply is greater than the preset safety threshold, it determines that the external power supply is overvoltage and controls the first switch unit 110 to be in the off state to disconnect the main power supply circuit 100 and avoid damage to the circuit and load due to overvoltage. If the voltage of the external power supply is less than or equal to the preset safety threshold, it determines that the external power supply is normal and controls the first switch unit 110 to be in the on state to conduct the main power supply circuit 100, so that the load 500 is powered on and operates normally.

[0058] Reference Figure 2 , Figure 2 The structure of a power input circuit is shown. In some embodiments, the auxiliary power circuit 200 further includes a second switching unit 230, a first terminal of which is connected to the input side of the step-down circuit 210, and a second terminal of which is connected to the output side of the step-down circuit 210; the control unit 400 is also connected to the second switching unit 230 and configured to control the second switching unit 230 to be turned on or off.

[0059] The second switching unit 230 has two states: on and off. When on, the two ends of the step-down circuit 210 are short-circuited, and the step-down circuit 210 does not work; when off, the step-down circuit 210 works normally. The second switching unit 230 may include switches such as relays.

[0060] The default state of the second switching unit 230 can be the off state. When the device is connected to the power supply, the second switching unit 230 is off, and the step-down circuit 210 works to step down the power supply voltage. When the control unit 400 detects that the external power supply is normal, it controls the second switching unit 230 to turn on, short-circuiting the two ends of the second switching unit 230, so that the second switching unit 230 does not work, which can reduce power consumption.

[0061] In some embodiments, the auxiliary power supply circuit 200 further includes a first rectifier circuit 240, the AC side of which is connected to the output side of the step-down circuit 210, and the output side of the first rectifier circuit 240 is connected to the input side of the switching power supply circuit 220.

[0062] The external power source connected to the power input node can be AC, and the output side of the step-down circuit 210 is also AC. The first rectifier circuit 240 rectifies the AC into DC, which facilitates voltage conversion by the switching power supply circuit 220.

[0063] In some embodiments, the detection circuit 300 includes a voltage divider sampling unit 310, which is connected between the positive and negative DC lines on the output side of the first rectifier circuit 240 and connected to the control unit 400. The voltage divider sampling unit 310 is configured to perform voltage divider sampling on the voltage between the positive and negative DC lines to provide a voltage detection signal.

[0064] The detection circuit 300 performs detection on the DC bus at the output side of the first rectifier circuit 240. DC sampling is simpler than AC sampling. The voltage divider sampling unit 310 can use series resistors to achieve voltage divider sampling.

[0065] A first capacitor C1 is typically provided on the DC bus of the output side of the first rectifier circuit 240, which can be used to stabilize the voltage of the DC bus. The voltage divider sampling unit 310 can be set after the bus capacitor, that is, between the bus capacitor and the switching power supply circuit 220. The DC bus voltage is more stable, and the voltage detection signal is more accurate.

[0066] As an example, the voltage divider sampling unit 310 may include a first resistor R1 and a second resistor R2. A first end of the first resistor R1 may be connected to the positive DC bus, and a second end of the first resistor R1 is connected to the first end of the second resistor R2. The second end of the second resistor R2 is connected to the negative DC bus. The connection point between the first resistor R1 and the second resistor R2 is connected to the control unit 400 to provide a feedback voltage detection signal.

[0067] The power input circuit may also include a fault indication unit 600, with the control unit 400 connected to the fault indication unit 600. The control unit 400 can display a fault indication via the fault indication unit 600 when an external power supply abnormality is detected, thus informing the operator of the occurrence of the fault. The control unit 400 can also display a fault indication via the fault indication unit 600 when an external power supply is detected to be normal, thus informing the operator of the normal operation.

[0068] As an example, the fault indication unit 600 may include an LED light. The control unit 400 may control the LED light to display red when an abnormality in the external power supply is detected, and control the LED light to display green when a normal external power supply is detected.

[0069] Continue to refer to Figure 2In some embodiments, the main power circuit 100 includes a second rectifier unit 120 and a power module 130. The AC side of the second rectifier unit 120 is connected to the first terminal of the first switching unit 110, and the second terminal of the first switching unit 110 is connected to the power input node. The input side of the power module 130 is connected to the DC side of the second rectifier unit 120, and the output side of the power module 130 is connected to the load 500.

[0070] The power module 130 can be an IPM (Intelligent Power Module) unit, which includes multiple power switching transistors. The power switching transistors can be MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors) or IGBTs (Insulated Gate Bipolar Transistors). The power switching transistors are used to construct power factor correction circuits and inverter circuits, etc., to drive the load 500 and improve power utilization efficiency.

[0071] The external power source connected to the power input node can be AC. The second rectifier unit 120 rectifies the AC into DC, facilitating voltage conversion by the power module 130. The first switching unit 110 is located before the second rectifier unit 120 and the power module 130. Before the first switching unit 110 is turned on, neither the second rectifier unit 120 nor the power module 130 has current, which can more effectively control the access of the external power source and reduce the risk of overvoltage.

[0072] A second capacitor C2 can be installed on the DC bus of the second rectifier unit 120 to stabilize the voltage on the DC bus. Additionally, a third resistor R3 and a fourth resistor R4 can be installed, connected in series between the positive and negative DC buses to achieve voltage division sampling.

[0073] In some embodiments, the power input node includes three-phase lines, and the first switching unit 110 includes a loop switch, a slow-start switch, and a slow-start resistor. At least two phase lines are provided with loop switches, and the slow-start switch and the slow-start resistor are connected in series and then connected in parallel with one of the loop switches.

[0074] The external power supply can be three-phase AC. The power input node is connected to three phase lines (UVW). Two or three phase lines are equipped with loop switches to effectively isolate the three-phase AC power. The slow-start switch and the slow-start resistor form a slow-start circuit. When the first switching unit 110 needs to be turned on, the slow-start switch is turned on for slow start, then the loop switch is turned on, and finally the slow-start switch is turned off to complete the start-up. Both the loop switch and the slow-start switch can be relays.

[0075] Reference Figure 3 , Figure 3 The structure of a first switching unit 110 is shown. As an example, the AC side of the second rectifier unit 120 is provided with phase lines L1, L2, and L3, and the DC side of the second rectifier unit 120 is also provided with a first inductor L1 to smooth the output voltage. The first switching unit 110 includes relays K1, K2, K3, and a first soft-start resistor RT1. Relay K1, as a soft-start switch, is connected in series with the first soft-start resistor RT1 to form a soft-start circuit. Relay K2 is located on phase line L1, and relay K3 is located on phase line L3, both serving as loop switches.

[0076] Reference Figure 4 , Figure 4 The structure of a power input circuit is shown. In some embodiments, the main power circuit 100 includes a second rectifier unit 120 and a power module 130. The AC side of the second rectifier unit 120 is connected to the power input node, and the DC side of the second rectifier unit 120 is connected to the first terminal of the first switching unit 110. The input side of the power module 130 is connected to the second terminal of the first switching unit 110, and the output side of the power module 130 is connected to the load 500.

[0077] and Figure 2 The power input circuit shown is different. The first switching unit 110 is located between the second rectifier unit 120 and the power module 130, and the first switching unit 110 is located on the DC line. Compared with the AC line, the arrangement of the first switching unit 110 is simpler, the control is simpler, and it is easier to implement.

[0078] In some embodiments, the first switching unit 110 includes a loop switch and a slow-start switch and a slow-start resistor connected in series. The loop switch is disposed on the positive DC line of the DC side of the second rectifier unit 120; the slow-start switch and the slow-start resistor are connected in series and then in parallel with the loop switch.

[0079] The positive DC line uses a loop switch to control power transmission; when the loop switch is open, power module 130 has no input. Similarly, a series-connected soft-start switch and soft-start resistor are used to achieve soft start, as detailed above.

[0080] Reference Figure 5 , Figure 5 The structure of a first switching unit 110 is shown. As an example, the first switching unit 110 includes a relay K4, a relay K5, and a second slow-start resistor RT2, which form a slow-start circuit. A second inductor L2 is also provided on the positive DC line of the DC side of the second rectifier unit 120 to smooth the output voltage, and the relay K5 is set as a loop switch after the second inductor L2.

[0081] One embodiment of this application also provides an air conditioner, which includes the power input circuit described above. The specific structure and principle of the power input circuit can be referred to in the foregoing embodiments, and it also has the corresponding technical effects, which will not be repeated here.

[0082] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. A power input circuit, characterized in that, include: The main power supply circuit has its input side connected to the power input node and its output side connected to the load. The first switching unit is located in the main power supply circuit; An auxiliary power supply circuit includes a step-down circuit and a switching power supply circuit connected in series. The input side of the step-down circuit is connected to the power input node, and the output side of the switching power supply circuit is used to provide auxiliary power. A detection circuit is connected to the auxiliary power supply circuit and configured to provide a voltage detection signal; The control unit is connected to the first switching unit and the detection circuit, and is configured to receive the voltage detection signal and control the first switching unit to turn on or off the main power supply circuit.

2. The power input circuit according to claim 1, characterized in that, The auxiliary power supply circuit also includes: The second switching unit has a first terminal connected to the input side of the step-down circuit and a second terminal connected to the output side of the step-down circuit. The control unit is also connected to the second switch unit and configured to control the second switch unit to be turned on or off.

3. The power input circuit according to claim 2, characterized in that, The auxiliary power supply circuit also includes: A first rectifier circuit, wherein the AC side of the first rectifier circuit is connected to the output side of the step-down circuit, and the output side of the first rectifier circuit is connected to the input side of the switching power supply circuit.

4. The power input circuit according to claim 3, characterized in that, The detection circuit includes: A voltage divider sampling unit is connected between the positive and negative DC lines on the output side of the first rectifier circuit and is connected to the control unit. The voltage divider sampling unit is configured to perform voltage divider sampling on the voltage between the positive and negative DC lines to provide the voltage detection signal.

5. The power input circuit according to any one of claims 1-4, characterized in that, The main power supply circuit includes: The second rectifier unit has its AC side connected to the first terminal of the first switching unit, and the second terminal of the first switching unit is connected to the power input node. The power module has its input side connected to the DC side of the second rectifier unit and its output side connected to the load.

6. The power input circuit according to claim 5, characterized in that, The power input node includes three-phase lines. The first switching unit includes a loop switch, a slow-start switch, and a slow-start resistor. At least two phase lines are equipped with the loop switch. The slow-start switch is connected in series with the slow-start resistor, and the series connection is then connected in parallel with one of the loop switches.

7. The power input circuit according to any one of claims 1-4, characterized in that, The main power supply circuit includes: The second rectifier unit has its AC side connected to the power input node and its DC side connected to the first terminal of the first switching unit. The power module has its input side connected to the second end of the first switching unit and its output side connected to the load.

8. The power input circuit according to claim 7, characterized in that, The first switching unit includes: A circuit switch is installed on the positive DC line on the DC side of the second rectifier unit; A slow-start switch and a slow-start resistor are connected in series, and then connected in parallel with the circuit switch.

9. The power input circuit according to any one of claims 1-4, characterized in that, The voltage levels that the power input node can access include 220V and 380V.

10. An air conditioner, characterized in that, The air conditioner includes a power input circuit according to any one of claims 1-9.

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