A control device and method for direct current power supply and air conditioner

Abstract

The present invention discloses a control device, method and air conditioner for a DC power supply, the device comprising: a control unit configured to determine the power-on time of the control unit itself after the three-phase AC power supply is powered on, when the control unit itself has been powered by a switching power supply, and to initiate a second switch instruction when the power-on time of the control unit itself reaches the set time; and to initiate a first switch instruction when there is no error in the wiring of the input end of the three-phase AC power supply; the first switch unit is configured to switch from a normally open state to a closed state when receiving the second switch instruction; the second switch unit is configured to switch from a normally open state to a closed state when receiving the first switch instruction. This scheme protects the DC load by controlling the DC load to not be powered when the phase sequence of the three-phase power is connected incorrectly.

Description

Technical Field

[0001] The present invention belongs to the technical field of power supply, and specifically relates to a control device and method of a DC power supply and an air conditioner, and more particularly to a DC power supply scheme and a DC load protection circuit and method, and an air conditioner having the DC power supply scheme and the DC load protection circuit. Background Art

[0002] With the development trend of variable frequency and DC of electrical appliances (such as air conditioners), DC loads are increasingly widely used. However, the application of DC loads brings about the problem of DC bus design.

[0003] In the relevant schemes, the DC bus is obtained by rectifying and filtering the AC power, and the bus filter capacitor uses a high-voltage bus capacitor. When the DC load (such as an air conditioning unit) is powered by three-phase electricity, the phase sequence is often connected incorrectly, which will cause abnormal DC load.

[0004] Figure 1 Figure 1 is a schematic diagram of the structure of a DC power supply circuit. Figure 1 The DC power supply circuit shown includes: AC power supply terminal H1, phase sequence control circuit, MCU, other weak DC load M2, capacitor C1, capacitor C2, diode D1, relay K1, switching power supply, neutral line N terminal, L1 phase line terminal, filter, resistor R1 (cement resistor), rectifier bridge DB1, and DC bus load M1.

[0005] Among them, the neutral line N connection port and the live line L connection port (specifically the phase line L1, the phase line L2 and the phase line L3) of the AC power supply terminal H1 are connected to the MCU after the phase sequence control circuit. After the DC power supply circuit is powered on and set for a long time, the control end of the MCU can send a control signal START1 to energize the coil of the relay K1 and close the normally open contact of the relay K1, so that the resistor R1 is short-circuited and cut out. The power supply end of the MCU is connected to the first connection end of the switching power supply, and the switching power supply can power the MCU. The second connection end of the switching power supply is connected to other weak DC loads M2. Capacitor C2 is connected in parallel with the first connection end of the rectifier bridge DB1 and the second connection end of the rectifier bridge DB1. The third connection end of the switching power supply is connected to the first connection end of the capacitor C2. The fourth connection end of the switching power supply is connected to the second connection end of the capacitor C2. The first connection end of the DC bus load M1 is connected to the first connection end of the capacitor C2. The second connection end of the DC bus load M1 is connected to the second connection end of the capacitor C2.

[0006] The DC power supply VDD is connected to the input end of the control signal START1 through the capacitor C1. The DC power supply VDD is connected to the cathode of the diode D1, and is also connected to the anode of the diode D1 through the coil of the relay K1. The input end of the control signal START1 is connected to the anode of the diode D1. The first connection end of the normally open contact of the relay K1 is connected to the first connection end of the resistor R1; the second connection end of the normally open contact of the relay K1 is connected to the second connection end of the resistor R1, and is also connected to the third connection end of the rectifier bridge DB1. The third connection end of the rectifier bridge DB1 is connected to the first connection end of the filter through the resistor R1. The fourth connection end of the rectifier bridge DB1 is connected to the second connection end of the filter. The third connection end of the filter is connected to the neutral line N terminal. The fourth connection end of the filter is connected to the L1 phase line terminal. When the DC power supply circuit is powered on, the resistor R1 limits the current to prevent the capacitor C2 from charging too fast, thereby protecting the capacitor C2. The resistor R1 is a cement resistor. The neutral line N terminal and the phase line L1 terminal are single-phase power supplies from a three-phase AC power supply.

[0007] Figure 1 The DC power supply circuit shown is a circuit for direct DC power supply after rectification and filtering of AC input. Figure 1 The DC power supply circuit shown has the problem of abnormal DC high voltage load due to wrong connection. For example, if the phase voltage Ua is mistakenly connected to the line voltage Uab, the busbar high voltage capacitor is damaged due to overvoltage; the DC load is damaged due to excessive DC voltage. Specifically, when the power supply of the electrical appliance (such as air conditioner) unit adopts three-phase power supply, if the power supply voltage of the mainboard is mistakenly connected from the phase voltage Ua to the line voltage Uab This will cause the high-voltage bus capacitor to be damaged due to overvoltage.

[0008] The above contents are only used to assist in understanding the technical solution of the present invention and do not constitute an admission that the above contents are prior art. Summary of the invention

[0009] The object of the present invention is to provide a control device, method and air conditioner for a DC power supply, so as to solve the problem that when the DC load of an electrical device is powered by three-phase electricity, if the phase sequence of the three-phase electricity is connected incorrectly, the DC load will be abnormal, so as to achieve the effect of protecting the DC load by controlling the DC load to not be powered when the phase sequence of the three-phase electricity is connected incorrectly.

[0010] The present invention provides a control device for a DC power supply, comprising: the DC power supply comprises: a switching power supply, a first switch unit, a first rectifier unit and a first bus capacitor unit; the DC power supply further comprises: a second switch unit, a second rectifier unit and a second bus capacitor unit; the control device for the DC power supply comprises: a control unit; wherein the single-phase AC power supply drawn from the input end of the three-phase AC power supply can provide a first bus voltage to supply power to a first DC bus load after passing through the first switch unit, the second switch unit, the first rectifier unit and the first bus capacitor unit; the first switch unit and the second switch unit are both in a normally open state; the single-phase AC power supply drawn from the input end of the three-phase AC power supply can provide a first bus voltage to supply power to a first DC bus load after passing through the second rectifier unit and the second bus capacitor unit After that, a second bus voltage can be provided to power the switching power supply; the switching power supply can power the control unit and the second DC bus load; wherein, the control unit is configured to initiate a first switching instruction after the three-phase AC power supply is powered on, when the control unit itself has been powered by the switching power supply and when there is no error in the wiring of the input end of the three-phase AC power supply; and determine the power-on time of the control unit itself, and initiate a second switching instruction when the power-on time of the control unit itself reaches the set time; the first switch unit is configured to switch from a normally open state to a closed state when the second switching instruction is received; the second switch unit is configured to switch from a normally open state to a closed state when the first switching instruction is received.

[0011] In some embodiments, the first bus capacitor module includes: a first capacitor; the second bus capacitor module includes: a second capacitor and a third capacitor, the second capacitor and the third capacitor are connected in series; wherein the capacitance of the first capacitor is greater than the capacitance of the second capacitor; and the capacitance of the first capacitor is greater than the capacitance of the third capacitor.

[0012] In some embodiments, the DC power supply further includes: at least one of a filtering unit and a protection unit; wherein, when the DC power supply further includes a filtering unit, the filtering unit is arranged between the single-phase AC power supply and the second rectifier unit; the single-phase AC power supply is connected to the second rectifier unit after passing through the filtering unit; the single-phase AC power supply is connected to the first switch unit and the first rectifier unit after passing through the filtering unit; when the DC power supply further includes a protection unit, the protection unit is arranged between the single-phase AC power supply and the second rectifier unit; the single-phase AC power supply is connected to the second rectifier unit after passing through the protection unit.

[0013] In some embodiments, when the DC power supply further includes a filtering unit and a protection unit, the neutral line of the single-phase AC power supply is connected to the input end of the first switch unit after passing through the filtering unit; the output end of the first switch unit is connected to the second input end of the first rectifier unit after passing through the second switch unit; the neutral line of the single-phase AC power supply is connected to the first input end of the second rectifier unit after passing through the filtering unit and the protection unit; the phase line of the single-phase AC power supply is connected to the first input end of the first rectifier unit and to the second input end of the second rectifier unit after passing through the filtering unit.

[0014] In some implementations, the protection unit includes: an NTC resistor.

[0015] In some embodiments, the first switch unit includes: a first relay and a first resistance module; the second switch unit includes: a second relay; wherein the normally open contact of the first relay is connected in parallel with the first resistance module; the normally open contact of the first relay and the normally open contact of the second relay are arranged in series between the neutral line of the single-phase AC power supply and the second input end of the first rectifier unit.

[0016] In some embodiments, the control device of the DC power supply further includes: a phase sequence detection unit; an input end of the three-phase AC power supply, connected to the control unit after passing through the phase sequence detection unit; wherein the phase sequence detection unit is configured to detect the current phase sequence of the three-phase AC power supply; the control unit, when there is no error in the wiring of the input end of the three-phase AC power supply, initiates a first switching instruction, including: determining whether the current phase sequence of the three-phase AC power supply has met the preset phase sequence, and when the current phase sequence of the three-phase AC power supply has met the preset phase sequence, determining that there is no error in the wiring of the input end of the three-phase AC power supply, and initiating the first switching instruction; and, when the second switch unit has switched from a normally open state to a closed state, determining the power-on time of the control unit itself, and initiating the second switching instruction when the power-on time of the control unit itself reaches the set time.

[0017] Matching the above device, the present invention provides an air conditioner on another aspect, comprising: a control device for the DC power supply mentioned above.

[0018] Matching the above-mentioned device, the present invention provides a control method of a DC power supply on another aspect, including: the DC power supply includes: a switching power supply, a first switch unit, a first rectifier unit and a first bus capacitor unit; the DC power supply also includes: a second switch unit, a second rectifier unit and a second bus capacitor unit; the control method of the DC power supply includes: after the three-phase AC power supply is powered on, the control unit itself is powered by the switching power supply, and there is no error in the wiring of the input end of the three-phase AC power supply, initiating a first switch instruction through a control unit; and determining the power-on time of the control unit itself, and initiating a second switch instruction when the power-on time of the control unit itself reaches a set time; controlling the first switch unit to switch from a normally open state to a closed state when the second switch instruction is received; and controlling the second switch unit to switch from a normally open state to a closed state when the first switch instruction is received.

[0019] In some embodiments, the first bus capacitor module includes: a first capacitor; the second bus capacitor module includes: a second capacitor and a third capacitor, the second capacitor and the third capacitor are connected in series; wherein the capacitance of the first capacitor is greater than the capacitance of the second capacitor; and the capacitance of the first capacitor is greater than the capacitance of the third capacitor.

[0020] In some embodiments, the control device of the DC power supply further includes: a phase sequence detection unit; an input end of the three-phase AC power supply, which is connected to the control unit after passing through the phase sequence detection unit; wherein, through the control unit, when there is no error in the wiring of the input end of the three-phase AC power supply, a first switching instruction is initiated, including: detecting the current phase sequence of the three-phase AC power supply through the phase sequence detection unit; determining whether the current phase sequence of the three-phase AC power supply has met the preset phase sequence, so as to determine that there is no error in the wiring of the input end of the three-phase AC power supply when the current phase sequence of the three-phase AC power supply has met the preset phase sequence, and initiating the first switching instruction; and, when the second switch unit has switched from a normally open state to a closed state, determining the power-on time of the control unit itself, and initiating the second switching instruction when the power-on time of the control unit itself reaches the set time.

[0021] Therefore, the scheme of the present invention uses two different groups of rectifying and filtering units (such as a rectifier bridge and a filter) for the switching power supply and the DC load, respectively, to rectify and filter the switching power supply and the DC load, supplies power to the MCU through the switching power supply, and controls whether the DC load is powered by the MCU. The DC load can be powered when the phase sequence of the three-phase power is normal, and the DC load cannot be powered when the phase sequence of the three-phase power is abnormal; thus, the DC load is controlled not to be powered when the phase sequence of the three-phase power is wrong, so as to protect the DC load.

[0022] Other features and advantages of the present invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the present invention.

[0023] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a structural schematic diagram of a DC power supply circuit;

[0025] Figure 2 It is a structural schematic diagram of an embodiment of a control device for a DC power supply of the present invention;

[0026] Figure 3 It is a structural schematic diagram of another DC power supply circuit;

[0027] Figure 4 for Figure 3 A control flow diagram of an embodiment of a DC power supply circuit shown;

[0028] Figure 5 A schematic flow chart of an embodiment of a method for controlling a DC power supply of the present invention;

[0029] Figure 6 It is a flowchart of an embodiment of initiating a first switch instruction in the method of the present invention. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention and the corresponding drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0031] In order to solve the high voltage problem of bus capacitor (i.e. Figure 1In order to solve the problem of damage of high-voltage bus capacitors due to overvoltage in the scheme shown in the figure, some schemes use four high-voltage capacitors in series and parallel (i.e., in series and / or in parallel). However, firstly, the high cost of high-voltage capacitors leads to high cost of this scheme; in addition, four high-voltage capacitors also occupy a large area of ​​PCB (printed circuit board); secondly, when four high-voltage capacitors are used in parallel, abnormal capacitance often occurs due to uneven voltage division, so the reliability is low, and finally some DC loads are also damaged or abnormal due to overvoltage.

[0032] According to an embodiment of the present invention, a control device for a DC power supply is provided. Figure 2 The structure diagram of an embodiment of the device of the present invention is shown. The DC power supply includes: a switching power supply, a first switch unit, a first rectifier unit and a first bus capacitor unit. The DC power supply also includes: a second switch unit, a second rectifier unit and a second bus capacitor unit. The control device of the DC power supply includes: a control unit. Figure 3 Schematic diagram of another DC power supply circuit. A first switch unit, such as relay K1. A second switch unit, such as relay K2. A first rectifier unit, such as rectifier bridge DB1. A second rectifier unit, such as rectifier bridge DB2. A first bus capacitor unit, such as capacitor C2. A second bus capacitor unit, such as capacitor C3 and capacitor C4. A control unit, such as MCU.

[0033] The single-phase AC power source (such as terminal N and terminal L1) derived from the input end of the three-phase AC power source (such as terminal N, terminal L1, terminal L2 and terminal L3) can provide a first bus voltage to supply power to the first DC bus load after passing through the first switch unit, the second switch unit, the first rectifier unit and the first bus capacitor unit. The first DC bus load is a high-voltage load. The first switch unit and the second switch unit are both in a normally open state.

[0034] The single-phase AC power source drawn from the input end of the three-phase AC power source can provide a second bus voltage after passing through the second rectifier unit and the second bus capacitor unit to power the switching power supply. The switching power supply can power the control unit and the second DC bus load. The second DC bus load is a weak current load.

[0035] Wherein, the control unit is configured to initiate a first switch instruction (such as control signal START2) after the three-phase AC power supply is powered on, when the control unit itself has been powered by the switching power supply, and when there is no error in the wiring of the input end of the three-phase AC power supply. The first switch instruction is used to control the second switch unit to change from an open state to a closed state. And, determine the power-on time of the control unit itself, and initiate a second switch instruction (such as control signal START1) when the power-on time of the control unit itself reaches a set time. The second switch instruction is used to control the first switch unit to change from an open state to a closed state. Determine the power-on time of the control unit itself, such as using an external timer or a clock module of the control unit itself to time the control unit itself and obtain the power-on time of the control unit itself.

[0036] The first switch unit is configured to switch from a normally open state to a closed state upon receiving the second switch instruction.

[0037] The second switch unit is configured to switch from a normally open state to a closed state upon receiving the first switch instruction.

[0038] In this way, the solution of the present invention solves the problem of overvoltage damage to DC load caused by wrong connection of three-phase power by setting two groups of rectification and filtering units (such as a first rectification unit and a first bus capacitor unit, a second rectification unit and a second bus capacitor unit), and setting two groups of switch units (such as a first switch unit and a second switch unit), and can achieve protection of both the bus of the switching power supply and the bus of the DC load.

[0039] In some embodiments, the first bus capacitor module includes: a first capacitor. The second bus capacitor module includes: a second capacitor and a third capacitor, wherein the second capacitor and the third capacitor are connected in series. The first capacitor is such as capacitor C2. The second capacitor is such as capacitor C3. The third capacitor is such as capacitor C4.

[0040] The capacitance of the first capacitor is greater than the capacitance of the second capacitor, and the capacitance of the first capacitor is greater than the capacitance of the third capacitor.

[0041] Thus, when a DC load is supplied with three-phase electricity, if the phase sequence of the three-phase electricity is connected incorrectly, the DC load may become abnormal. Figure 3 The capacitors C3 and C4 in the figure are connected in series to increase the withstand voltage of the busbar. Large-capacity capacitors (such as Figure 3The capacitor C2 in the circuit is controlled by the MCU, which solves the problem of overvoltage damage to the DC load caused by wrong connection of the three-phase power supply. It can protect the high-voltage DC load and improve the reliability of the DC power supply solution.

[0042] In addition, in order to solve the high voltage problem of bus capacitors (i.e., the problem of high voltage bus capacitors being damaged due to overvoltage), when four high voltage capacitors are used in series and parallel (i.e., in series and / or in parallel), the high voltage capacitors have high cost, large occupied area, uneven voltage division and other problems. In the related scheme, four electrolytic capacitors are first used in series and parallel (i.e., in series and / or in parallel). The scheme of the present invention uses two small-capacity capacitors in series (e.g., Figure 3 Capacitors C3 and C4 in the figure are used to power the MCU, and the DC load power supply capacitors (such as Figure 3 The capacitor C2 in the circuit is controlled by the MCU, which generally solves the problems of high cost, large PCB board space, uneven voltage division, etc. when four DC loads are powered by capacitors connected in series and parallel, and can reduce costs, reduce PCB board area, and achieve uniform voltage division. In other words, the solution of the present invention can reduce costs, reduce PCB board area, and achieve uniform voltage division compared to the solution of four electrolytic capacitors connected in series and parallel.

[0043] In some embodiments, the DC power supply further includes: at least one of a filtering unit and a protection unit. The filtering unit is such as a filter. The protection unit is such as a resistor R2. When the resistor R2 is an NTC resistor, overcurrent protection can be achieved with low power, low energy consumption, and small space occupation.

[0044] Wherein, when the DC power supply further includes a filter unit, the filter unit is arranged between the single-phase AC power supply and the second rectifier unit. The single-phase AC power supply is connected to the second rectifier unit after passing through the filter unit. The single-phase AC power supply is connected to the first switch unit and the first rectifier unit after passing through the filter unit.

[0045] In the case where the DC power supply further includes a protection unit, the protection unit is disposed between the single-phase AC power supply and the second rectifier unit. The single-phase AC power supply is connected to the second rectifier unit after passing through the protection unit.

[0046] In some embodiments, when the DC power supply further includes a filter unit and a protection unit, the neutral line of the single-phase AC power supply, such as the neutral line N, is connected to the input end of the first switch unit after passing through the filter unit. The output end of the first switch unit is connected to the second input end of the first rectifier unit after passing through the second switch unit.

[0047] The neutral line of the single-phase AC power source is connected to the first input end of the second rectifying unit after passing through the filtering unit and the protection unit.

[0048] The phase line of the single-phase AC power source, such as the phase line L1, is connected to the first input end of the first rectifier unit and to the second input end of the second rectifier unit after passing through the filter unit.

[0049] Wherein, the first rectifying unit and the second rectifying unit can both be diode rectifier bridges.

[0050] In some embodiments, the protection unit includes: an NTC resistor, that is, the resistor R2 is an NTC resistor. The use of the NTC resistor can achieve overcurrent protection, and has low power, low energy consumption, and small space occupation.

[0051] In some embodiments, the first switch unit includes: a first relay and a first resistor module. The first relay, such as relay K1, and the first resistor module, such as resistor R1, can play a protective function, such as current limiting, so that the voltage is not too high when charging capacitor C2, and is short-circuited after the first switch unit is turned on, meeting the voltage requirement of the subsequent DC load. Of course, the first switch unit also includes peripheral components such as capacitor C1 and diode D1.

[0052] The second switch unit includes: a second relay. The second relay is a relay K2. Of course, the second switch unit also includes peripheral components such as a capacitor C5 and a diode D2.

[0053] The normally open contact of the first relay is connected in parallel with the first resistor module, and the normally open contact of the first relay and the normally open contact of the second relay are connected in series between the neutral line of the single-phase AC power supply and the second input end of the first rectifier unit.

[0054] In some embodiments, the control device of the DC power supply further includes: a phase sequence detection unit, such as a phase sequence control circuit. The input end of the three-phase AC power supply, such as the neutral line N connection port and the live line L connection port (specifically the phase line L1, the phase line L2 and the phase line L3) of the AC power supply terminal H1, is connected to the control unit after passing through the phase sequence detection unit. The phase sequence detection unit is such as a phase sequence control circuit.

[0055] Wherein, the phase sequence detection unit is configured to detect the current phase sequence of the three-phase AC power supply.

[0056] The control unit, when there is no error in the wiring of the input end of the three-phase AC power supply, initiates a first switch instruction, including:

[0057] The control unit is specifically configured to determine whether the current phase sequence of the three-phase AC power supply meets the preset phase sequence, so that when the current phase sequence of the three-phase AC power supply meets the preset phase sequence, it is determined that there is no error in the wiring of the input end of the three-phase AC power supply, and the first switch instruction is initiated. In order to make the phase sequence detection result more accurate, it can be considered that the current phase sequence of the three-phase AC power supply is determined to meet the preset phase sequence only when it is detected within a certain time (such as the first set time A seconds) that the current phase sequence of the three-phase AC power supply meets the preset phase sequence. And, when the second switch unit has been switched from the normally open state to the closed state, the power-on time of the control unit itself is determined, and when the power-on time of the control unit itself reaches the set time (such as the second set time B seconds), the second switch instruction is initiated. Of course, when the current phase sequence of the three-phase AC power supply does not meet the preset phase sequence, it is determined that there is an error in the wiring of the input end of the three-phase AC power supply, and the first switch instruction is not initiated.

[0058] like Figure 3 The DC power supply circuit shown includes: AC power supply terminal H1, phase sequence control circuit, MCU, other weak DC load M2, capacitor C1, capacitor C2, capacitor C3, capacitor C4, capacitor C5, diode D1, diode D2, relay K1, relay K2, switch power supply, neutral line N terminal, L1 phase line terminal, filter, resistor R1, resistor R2, rectifier bridge DB1, rectifier bridge DB1, and DC bus load M1. Resistor R1 uses cement resistor, and resistor R2 uses NTC (negative temperature coefficient) resistor. Neutral line N terminal and L1 phase line terminal are single-phase power from three-phase AC power.

[0059] Among them, the neutral wire N connection port and the live wire L connection port (specifically the phase line L1, phase line L2 and phase line L3) of the AC power supply terminal H1 are connected to the MCU after passing through the phase sequence control circuit. After the DC power supply circuit is powered on for a set period of time, the control end of the MCU can send a control signal START1 to energize the coil of the relay K1 and close the normally open contact of the relay K1, so that the resistor R1 is short-circuited and cut out. After the phase sequence control circuit detects the wiring phase sequence of the three-phase AC power supply, the MCU sends a control signal START2 based on the detection result of the phase sequence control circuit, if the phase sequence is correct, so that the coil of the relay K2 is energized and the normally open contact of the relay K2 is closed. After the coils of the relays K1 and K2 are both energized and the corresponding normally open contacts are closed, the capacitor C2 can be charged normally and the DC bus load M1 can be energized.

[0060] The power supply end of the MCU is connected to the first connection end of the switching power supply, and the switching power supply can supply power to the MCU. The second connection end of the switching power supply is connected to other weak DC loads M2. Capacitor C2 is connected in parallel with the first connection end of the rectifier bridge DB1 and the second connection end of the rectifier bridge DB1. The third connection end of the switching power supply is connected to the first connection end of the capacitor C3 and the capacitor C4 connected in series. The fourth connection end of the switching power supply is connected to the second connection end of the capacitor C3 and the capacitor C4 connected in series. The first connection end of the capacitor C3 and the capacitor C4 connected in series is connected to the first connection end of the rectifier bridge DB2. The second connection end of the capacitor C3 and the capacitor C4 connected in series is connected to the second connection end of the rectifier bridge DB2. The third connection end of the rectifier bridge DB2 is connected to the first connection end of the filter after the resistor R2. The third connection end of the rectifier bridge DB2 is connected to the second connection end of the filter.

[0061] The first connection terminal of the DC bus load M1 is connected to the first connection terminal of the capacitor C2. The second connection terminal of the DC bus load M1 is connected to the second connection terminal of the capacitor C2. The DC power supply VDD is connected to the input terminal of the control signal START1 through the capacitor C1. The DC power supply VDD is connected to the cathode of the diode D1, and is also connected to the anode of the diode D1 through the coil of the relay K1. The input terminal of the control signal START1 is connected to the anode of the diode D1. The first connection terminal of the normally open contact of the relay K1 is connected to the first connection terminal of the resistor R1. The second connection terminal of the normally open contact of the relay K1 is connected to the second connection terminal of the resistor R1, and is also connected to the third connection terminal of the rectifier bridge DB1 through the normally open contact of the relay K2. The third connection terminal of the rectifier bridge DB1 is connected to the first connection terminal of the filter through the normally open contact of the relay K2 and the resistor R1. The fourth connection terminal of the rectifier bridge DB1 is connected to the second connection terminal of the filter. The third connection terminal of the filter is connected to the neutral line N terminal. The fourth connection terminal of the filter is connected to the L1 phase line terminal. When the DC power supply circuit is powered on, resistor R1 limits the current to prevent capacitor C2 from charging too quickly, thereby protecting capacitor C2. The coil of relay K2 is connected in parallel with diode D2 and capacitor C5. The anode of diode D2 is connected to the input end of control signal START2. The cathode of diode D2 is connected to the DC power supply VDD.

[0062] Figure 3 The DC power supply circuit shown is a circuit in which the rectified and filtered high-voltage bus first supplies power to the MCU, while the DC load is powered by a separate controlled rectified and filtered bus. This is a circuit with high reliability and protection of high-voltage DC loads.

[0063] exist Figure 3In the example shown, two capacitors with smaller capacitance are connected in series. After the two capacitors with smaller capacitance are connected in series, the withstand voltage can reach 900V, which can meet the requirement that the capacitor will not be damaged if the wiring is wrong. For capacitors with larger capacitance, the time when the DC bus capacitor is powered on is controlled by a relay to protect the high-voltage DC load. For example: through the MCU controller relay, the charging and discharging time of the large capacitor is controlled to protect the motor.

[0064] Figure 4 for Figure 3 The control flow diagram of an embodiment of a DC power supply circuit is shown in FIG. Figure 4 As shown, Figure 3 The control process of the DC power supply circuit shown includes:

[0065] Step 1: Use two different rectifier bridges (such as rectifier bridge DB1 and rectifier bridge DB2) to rectify, filter and supply power to the switching power supply and the DC load (such as DC bus load M1).

[0066] The bus power supply of the switching power supply is rectified by the rectifier bridge DB2, and filtered after the capacitors C3 and C4 are connected in series. After the capacitors C3 and C4 are connected in series, the withstand voltage of the bus reaches 900V.

[0067] Resistor R2 is an NTC resistor. Since the busbar capacitor is only two electrolytic capacitors of tens of microfarads connected in series (capacitor C3 and capacitor C4 are connected in series), the NTC resistor can meet the power-on requirements.

[0068] The power supply of the DC load (such as the DC bus load M1) is rectified and filtered by the rectifier bridge DB1 and the capacitor C2, and the charging and discharging time points of the bus capacitor of the DC bus load M2 (such as the fan) are controlled by the relay K2, and the relay K1 controls the connection and disconnection of the cement resistor (i.e., the resistor R1).

[0069] Step 2: When the mainboard power supply voltage is connected to the normal phase voltage 220VAC, the power supply end of the switch power supply is powered first, and the power supply end of the DC load (such as the DC bus load M1) is not powered. The main chip MCU starts to work, and the MCU detects whether the three-phase power phase sequence is correct through the phase sequence control circuit. When the MCU detects that the phase sequence is normal within the first set time A seconds, the control relay K2 is closed, and the bus capacitor C2 of the DC load (such as the DC bus load M1) starts to charge. After the second set time B seconds, the capacitor is charged, the relay K1 is closed, and the mainboard and the load work normally.

[0070] When the motherboard power supply voltage is mistakenly connected to the line voltage of 380VAC, the power supply end of the switching power supply is powered first, and the bus voltage is 537VDC. Figure 1 The solution shown uses a capacitor C2, but the busbar withstand voltage is not enough, causing the busbar capacitor to burn out due to overvoltage. Figure 3 In the scheme shown, the bus uses two small-capacity capacitors (capacitor C3 and capacitor C4 are connected in series) to improve the bus's withstand voltage value. Even if the line is connected incorrectly, the bus can be powered normally, the switching power supply can work normally, and the MCU can be powered normally. The MCU detects the correctness of the phase sequence through the phase sequence controller circuit. If an abnormal phase sequence is detected, the relay K2 will not operate, thereby achieving the purpose of protecting the DC load (such as the fan), and the main board reports a phase sequence fault.

[0071] Thus, the solution of the present invention provides a high reliability DC power supply solution and a DC load protection circuit, firstly using two extremely small high voltage bus capacitors (such as Figure 3 Capacitors C3 and C4 in the control circuit are used in series to supply power to the switching power supply with lower power, and the switching power supply is used to supply power to the MCU and DC load with lower working voltage. After the MCU works normally, the high-voltage bus capacitor (such as Figure 3 The capacitor C2 in the circuit works to achieve high reliability and protect high voltage DC loads.

[0072] For example: the parameter range of high-voltage bus capacitors with extremely small capacity, such as withstand voltage above 450V and capacitance below 150UF. The parameter range of high-voltage bus capacitors with large power requirements, such as withstand voltage above 450V and capacitance above 150UF.

[0073] After a large number of tests and verifications, the technical solution of the present invention is adopted, by using two different sets of rectification and filtering units (such as rectifier bridge and filter) for the switching power supply and the DC load, respectively, to rectify and filter the switching power supply and the DC load, and then supply power to the MCU through the switching power supply, and the MCU controls whether the DC load is powered, so that the DC load can be powered when the phase sequence of the three-phase power is normal, and the DC load cannot be powered when the phase sequence of the three-phase power is abnormal. Therefore, the DC load is controlled not to be powered when the phase sequence of the three-phase power is wrong, so as to protect the DC load.

[0074] According to an embodiment of the present invention, an air conditioner corresponding to a control device of a DC power supply is also provided. The air conditioner may include: the control device of the DC power supply described above.

[0075] Since the processing and functions implemented by the air conditioner of this embodiment basically correspond to the embodiments, principles and examples of the aforementioned devices, for the details not fully described in this embodiment, please refer to the relevant descriptions in the aforementioned embodiments and will not be repeated here.

[0076] After a large number of experimental verifications, the technical solution of the present invention is adopted. For the switching power supply and the DC load, the switching power supply and the DC load are respectively rectified and filtered by two groups of different rectification and filtering units (such as a rectifier bridge and a filter) to supply power. The MCU is powered by the switching power supply, and the MCU controls whether the DC load is powered. When the phase sequence of the three-phase electricity is normal, the DC load can be powered, and when the phase sequence of the three-phase electricity is abnormal, the DC load cannot be powered. It can protect both the switching power supply bus and the DC load bus.

[0077] According to an embodiment of the present invention, a control method for a DC power supply corresponding to an air conditioner is also provided. Figure 5 The flow chart of an embodiment of the method of the present invention is shown. The DC power supply includes: a switching power supply, a first switch unit, a first rectifier unit and a first bus capacitor unit. The DC power supply also includes: a second switch unit, a second rectifier unit and a second bus capacitor unit. Figure 3 A schematic diagram of the structure of another DC power supply circuit. A first switch unit, such as a relay K1. A second switch unit, such as a relay K2. A first rectifier unit, such as a rectifier bridge DB1. A second rectifier unit, such as a rectifier bridge DB2. A first bus capacitor unit, such as a capacitor C2. A second bus capacitor unit, such as a capacitor C3 and a capacitor C4. A control unit, such as an MCU. The control method of the DC power supply includes: steps S110 to S130.

[0078] At step S110, after the three-phase AC power supply is powered on, the control unit itself is powered by the switching power supply, and there is no error in the wiring of the input end of the three-phase AC power supply. The first switch instruction is used to control the second switch unit to change from an open state to a closed state. In addition, the power-on time of the control unit itself is determined, and when the power-on time of the control unit itself reaches the set time, a second switch instruction (such as control signal START1) is initiated. The second switch instruction is used to control the first switch unit to change from an open state to a closed state. The power-on time of the control unit itself is determined, such as by using an external timer or a clock module of the control unit itself to time the control unit itself and obtain the power-on time of the control unit itself.

[0079] In step S120, the first switch unit is controlled to switch from a normally open state to a closed state when the second switch instruction is received.

[0080] In step S130, the second switch unit is controlled to switch from a normally open state to a closed state when the first switch instruction is received.

[0081] In this way, the solution of the present invention solves the problem of overvoltage damage to DC load caused by wrong connection of three-phase power by setting two groups of rectification and filtering units (such as a first rectification unit and a first bus capacitor unit, a second rectification unit and a second bus capacitor unit), and setting two groups of switch units (such as a first switch unit and a second switch unit), and can achieve protection of both the bus of the switching power supply and the bus of the DC load.

[0082] In some embodiments, the first bus capacitor module includes: a first capacitor. The second bus capacitor module includes: a second capacitor and a third capacitor, wherein the second capacitor and the third capacitor are connected in series. The first capacitor is such as capacitor C2. The second capacitor is such as capacitor C3. The third capacitor is such as capacitor C4.

[0083] The capacitance of the first capacitor is greater than the capacitance of the second capacitor, and the capacitance of the first capacitor is greater than the capacitance of the third capacitor.

[0084] Thus, when a DC load is supplied with three-phase electricity, if the phase sequence of the three-phase electricity is connected incorrectly, the DC load may become abnormal. Figure 3 The capacitors C3 and C4 in the figure are connected in series to increase the withstand voltage of the busbar. Large-capacity capacitors (such as Figure 3 The capacitor C2 in the circuit is controlled by the MCU, which solves the problem of overvoltage damage to the DC load caused by wrong connection of the three-phase power supply. It can protect the high-voltage DC load and improve the reliability of the DC power supply solution.

[0085] In addition, in order to solve the high voltage problem of bus capacitors (i.e., the problem of high voltage bus capacitors being damaged due to overvoltage), when four high voltage capacitors are used in series and parallel (i.e., in series and / or in parallel), the high voltage capacitors have high cost, large occupied area, uneven voltage division and other problems. The solution of the present invention can first use four electrolytic capacitors in series and parallel (i.e., in series and / or in parallel), and then use two small-capacity capacitors in series (e.g., Figure 3 Capacitors C3 and C4 in the figure are used to power the MCU, and the DC load power supply capacitors (such as Figure 3 The capacitor C2 in the circuit is controlled by the MCU, which generally solves the problems of high cost, large PCB board space, uneven voltage division, etc. when four DC loads are powered by capacitors connected in series and parallel, and can reduce costs, reduce PCB board area, and achieve uniform voltage division. In other words, the solution of the present invention can reduce costs, reduce PCB board area, and achieve uniform voltage division compared to the solution of four electrolytic capacitors connected in series and parallel.

[0086] In some embodiments, the control device of the DC power supply further includes: a phase sequence detection unit. The input end of the three-phase AC power supply is connected to the control unit after passing through the phase sequence detection unit. The phase sequence detection unit is such as a phase sequence control circuit.

[0087] For the specific process of initiating the first switch instruction by the control unit in step S120 when there is no error in the wiring of the input end of the three-phase AC power supply, refer to the following exemplary description.

[0088] Combine the following Figure 6 The flowchart of an embodiment of initiating the first switch instruction in the method of the present invention is shown, which further illustrates the specific process of initiating the first switch instruction in step S120, including: step S210 and step S220.

[0089] Step S210: Detecting the current phase sequence of the three-phase AC power supply through a phase sequence detection unit.

[0090] Step S220, through the control unit, determine whether the current phase sequence of the three-phase AC power supply has met the preset phase sequence, so that when the current phase sequence of the three-phase AC power supply has met the preset phase sequence, it is determined that there is no error in the wiring of the input end of the three-phase AC power supply, and the first switch instruction is initiated. Wherein, in order to make the phase sequence detection result more accurate, it can be considered that the current phase sequence of the three-phase AC power supply is determined to meet the preset phase sequence only when it is detected within a certain time (such as the first set time A seconds) that the current phase sequence of the three-phase AC power supply meets the preset phase sequence. And, when the second switch unit has been switched from the normally open state to the closed state, the power-on time of the control unit itself is determined, and when the power-on time of the control unit itself reaches the set time (such as the second set time B seconds), the second switch instruction is initiated. Of course, when the current phase sequence of the three-phase AC power supply does not meet the preset phase sequence, it is determined that there is an error in the wiring of the input end of the three-phase AC power supply, and the first switch instruction is not initiated.

[0091] Figure 3 The DC power supply circuit shown is a circuit in which the rectified and filtered high-voltage bus first supplies power to the MCU, while the DC load is powered by a separate controlled rectified and filtered bus. This is a circuit with high reliability and protection of high-voltage DC loads.

[0092] exist Figure 3In the example shown, two capacitors with smaller capacitance are connected in series. After the two capacitors with smaller capacitance are connected in series, the withstand voltage can reach 900V, which can meet the requirement that the capacitor will not be damaged if the wiring is wrong. For capacitors with larger capacitance, the time when the DC bus capacitor is powered on is controlled by a relay to protect the high-voltage DC load. For example: through the MCU controller relay, the charging and discharging time of the large capacitor is controlled to protect the motor.

[0093] Figure 4 for Figure 3 The control flow diagram of an embodiment of a DC power supply circuit is shown in FIG. Figure 4 As shown, Figure 3 The control process of the DC power supply circuit shown includes:

[0094] Step 1: Use two different rectifier bridges (such as rectifier bridge DB1 and rectifier bridge DB2) to rectify, filter and supply power to the switching power supply and the DC load (such as DC bus load M1).

[0095] The bus power supply of the switching power supply is rectified by the rectifier bridge DB2, and filtered after the capacitors C3 and C4 are connected in series. After the capacitors C3 and C4 are connected in series, the withstand voltage of the bus reaches 900V.

[0096] Resistor R2 is an NTC resistor. Since the busbar capacitor is only two electrolytic capacitors of tens of microfarads connected in series (capacitor C3 and capacitor C4 are connected in series), the NTC resistor can meet the power-on requirements.

[0097] The power supply of the DC load (such as the DC bus load M1) is rectified and filtered by the rectifier bridge DB1 and the capacitor C2, and the charging and discharging time points of the bus capacitor of the DC bus load M2 (such as the fan) are controlled by the relay K2, and the relay K1 controls the connection and disconnection of the cement resistor (i.e., the resistor R1).

[0098] Step 2: When the mainboard power supply voltage is connected to the normal phase voltage 220VAC, the power supply end of the switch power supply is powered first, and the power supply end of the DC load (such as the DC bus load M1) is not powered. The main chip MCU starts to work, and the MCU detects whether the three-phase power phase sequence is correct through the phase sequence control circuit. When the MCU detects that the phase sequence is normal within the first set time A seconds, the control relay K2 is closed, and the bus capacitor C2 of the DC load (such as the DC bus load M1) starts to charge. After the second set time B seconds, the capacitor is charged, the relay K1 is closed, and the mainboard and the load work normally.

[0099] When the motherboard power supply voltage is mistakenly connected to the line voltage of 380VAC, the power supply end of the switching power supply is powered first, and the bus voltage is 537VDC. Figure 1 The solution shown uses a capacitor C2, but the busbar withstand voltage is not enough, causing the busbar capacitor to burn out due to overvoltage. Figure 3 In the scheme shown, the bus uses two small-capacity capacitors (capacitor C3 and capacitor C4 are connected in series) to improve the bus's withstand voltage value. Even if the line is connected incorrectly, the bus can be powered normally, the switching power supply can work normally, and the MCU can be powered normally. The MCU detects the correctness of the phase sequence through the phase sequence controller circuit. If an abnormal phase sequence is detected, the relay K2 will not operate, thereby achieving the purpose of protecting the DC load (such as the fan), and the main board reports a phase sequence fault.

[0100] Thus, the solution of the present invention provides a high reliability DC power supply solution and a DC load protection circuit, firstly using two extremely small high voltage bus capacitors (such as Figure 3 Capacitors C3 and C4 in the control circuit are used in series to supply power to the switching power supply with lower power, and the switching power supply is used to supply power to the MCU and DC load with lower working voltage. After the MCU works normally, the high-voltage bus capacitor (such as Figure 3 The capacitor C2 in the circuit works to achieve high reliability and protect high voltage DC loads.

[0101] Since the processing and functions implemented by the method of this embodiment basically correspond to the embodiments, principles and examples of the aforementioned air conditioner, for the details not fully described in this embodiment, please refer to the relevant descriptions in the aforementioned embodiments, and no further elaboration will be made here.

[0102] After a large number of experimental verifications, the technical solution of this embodiment is adopted. For the switching power supply and the DC load, the switching power supply and the DC load are respectively rectified and filtered by two groups of different rectification and filtering units (such as a rectifier bridge and a filter) to supply power. The MCU is powered by the switching power supply, and the MCU controls whether the DC load is powered. When the phase sequence of the three-phase electricity is normal, the DC load can be powered, and when the phase sequence of the three-phase electricity is abnormal, the DC load cannot be powered, thereby achieving high reliability and protecting the high-voltage DC load.

[0103] In summary, it is easy for those skilled in the art to understand that, under the premise of no conflict, the above-mentioned advantageous methods can be freely combined and superimposed.

[0104] The above description is only an embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention shall be included in the scope of the claims of the present invention.

Claims

1. A control device for a DC power supply, characterized in that: The DC power supply comprises: a switching power supply, a first switching unit, a first rectifying unit and a first bus capacitor unit; the DC power supply further comprises: a second switching unit, a second rectifying unit and a second bus capacitor unit; the control device of the DC power supply comprises: a control unit; wherein, The single-phase AC power source derived from the input end of the three-phase AC power source can provide a first bus voltage to supply power to the first DC bus load after passing through the first switch unit, the second switch unit, the first rectifier unit and the first bus capacitor unit; the first switch unit and the second switch unit are both in a normally open state; The single-phase AC power source drawn from the input end of the three-phase AC power source can provide a second bus voltage after passing through the second rectifier unit and the second bus capacitor unit to power the switching power supply; the switching power supply can power the control unit and the second DC bus load; in, The control unit is configured to, after the three-phase AC power supply is powered on, initiate a first switching instruction when the control unit itself is powered by the switching power supply and when there is no error in the wiring of the input end of the three-phase AC power supply; and determine the power-on time of the control unit itself, and initiate a second switching instruction when the power-on time of the control unit itself reaches a set time; The first switch unit is configured to switch from a normally open state to a closed state when receiving the second switch instruction; The second switch unit is configured to switch from a normally open state to a closed state when receiving the first switch instruction; the switching power supply and the DC load are respectively supplied with power after rectification and filtering by two different sets of rectification and filtering units, the MCU is supplied with power by the switching power supply, and whether the DC load is powered is controlled by the MCU, and the DC load is powered when the phase sequence of the three-phase power is normal, and the DC load is not powered when the phase sequence of the three-phase power is abnormal.

2. The control device of the DC power supply according to claim 1, characterized in that: The first bus capacitor module includes: a first capacitor; the second bus capacitor module includes: a second capacitor and a third capacitor, the second capacitor and the third capacitor are connected in series; wherein, The capacitance of the first capacitor is greater than the capacitance of the second capacitor; and the capacitance of the first capacitor is greater than the capacitance of the third capacitor.

3. The control device of the DC power supply according to claim 1, characterized in that: The DC power supply further includes: at least one of a filtering unit and a protection unit; wherein, In the case where the DC power supply further includes a filter unit, the filter unit is arranged between the single-phase AC power supply and the second rectifier unit; the single-phase AC power supply is connected to the second rectifier unit after passing through the filter unit; the single-phase AC power supply is connected to the first switch unit and the first rectifier unit after passing through the filter unit; In the case where the DC power supply further includes a protection unit, the protection unit is disposed between the single-phase AC power supply and the second rectifier unit; the single-phase AC power supply is connected to the second rectifier unit after passing through the protection unit.

4. The control device of the DC power supply according to claim 3, characterized in that: In the case where the DC power supply further includes a filtering unit and a protection unit, The neutral line of the single-phase AC power source is connected to the input end of the first switch unit after passing through the filter unit; the output end of the first switch unit is connected to the second input end of the first rectifier unit after passing through the second switch unit; The neutral line of the single-phase AC power supply is connected to the first input end of the second rectifier unit after passing through the filter unit and the protection unit; The phase line of the single-phase AC power source is connected to the first input end of the first rectifier unit and to the second input end of the second rectifier unit after passing through the filter unit.

5. The control device of the DC power supply according to claim 3, characterized in that: The protection unit includes: an NTC resistor.

6. The control device of the DC power supply according to claim 1, characterized in that: The first switch unit comprises: a first relay and a first resistance module; The second switch unit comprises: a second relay; in, The normally open contact of the first relay is connected in parallel with the first resistance module; the normally open contact of the first relay and the normally open contact of the second relay are arranged in series between the neutral line of the single-phase AC power supply and the second input end of the first rectifier unit.

7. The control device of a DC power supply according to any one of claims 1 to 6, characterized in that: The control device of the DC power supply further includes: a phase sequence detection unit; an input end of the three-phase AC power supply is connected to the control unit after passing through the phase sequence detection unit; wherein, The phase sequence detection unit is configured to detect a current phase sequence of the three-phase AC power supply; The control unit, when there is no error in the wiring of the input end of the three-phase AC power supply, initiates a first switch instruction, including: Determine whether the current phase sequence of the three-phase AC power supply has satisfied the preset phase sequence, and when the current phase sequence of the three-phase AC power supply has satisfied the preset phase sequence, determine that there is no error in the wiring of the input end of the three-phase AC power supply, and initiate a first switching instruction; and, when the second switch unit has switched from a normally open state to a closed state, determine the power-on time of the control unit itself, and when the power-on time of the control unit itself reaches the set time, initiate a second switching instruction.

8. An air conditioner, characterized in that: include: A control device for a DC power supply according to any one of claims 1 to 7.

9. A method for controlling a DC power supply of an air conditioner as claimed in claim 8, characterized in that: The DC power supply comprises: a switching power supply, a first switching unit, a first rectifying unit and a first bus capacitor unit; the DC power supply further comprises: a second switching unit, a second rectifying unit and a second bus capacitor unit; the control method of the DC power supply comprises: By means of a control unit, after the three-phase AC power supply is powered on, when the control unit itself is powered by the switching power supply, determining the power-on time of the control unit itself, and initiating a second switching instruction when the power-on time of the control unit itself reaches a set time; and Initiating a first switch instruction when there is no error in the wiring of the input end of the three-phase AC power supply; Controlling the first switch unit to switch from a normally open state to a closed state when receiving the second switch instruction; The second switch unit is controlled to switch from a normally open state to a closed state when the first switch instruction is received.

10. The control method of the DC power supply according to claim 9, characterized in that: The first bus capacitor module includes: a first capacitor; the second bus capacitor module includes: a second capacitor and a third capacitor, the second capacitor and the third capacitor are connected in series; wherein, The capacitance of the first capacitor is greater than the capacitance of the second capacitor; and the capacitance of the first capacitor is greater than the capacitance of the third capacitor.

11. The control method of a DC power supply according to claim 9 or 10, characterized in that: The control device of the DC power supply further includes: a phase sequence detection unit; an input end of the three-phase AC power supply is connected to the control unit after passing through the phase sequence detection unit; wherein, Initiating a first switch instruction by a control unit when there is no error in the wiring of the input end of the three-phase AC power supply includes: Detecting the current phase sequence of the three-phase AC power supply by a phase sequence detection unit; Determine whether the current phase sequence of the three-phase AC power supply has satisfied the preset phase sequence, and when the current phase sequence of the three-phase AC power supply has satisfied the preset phase sequence, determine that there is no error in the wiring of the input end of the three-phase AC power supply, and initiate a first switching instruction; and, when the second switch unit has switched from a normally open state to a closed state, determine the power-on time of the control unit itself, and when the power-on time of the control unit itself reaches the set time, initiate a second switching instruction.

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