Multifunctional inverter circuit, control method, compressor and air conditioner

Abstract

The present invention discloses a multifunctional inverter circuit, a control method, a compressor and an air conditioner. The multifunctional inverter circuit includes: a three-phase bridge circuit, each phase branch is provided with two sets of upper and lower main switch tubes; a three-phase load is connected to each phase branch in the three-phase bridge circuit; a two-phase load is connected to the two-phase branch in the three-phase bridge circuit after the first switch is connected in series, and the remaining one-phase branch in the three-phase bridge circuit is a regulating branch; a control module controls the on-off state of the first switch and the regulating branch to switch on the three-phase load or the two-phase load. The multifunctional inverter circuit also includes: a soft switch auxiliary circuit and a resonant capacitor. The soft switch auxiliary circuit is connected in parallel with the two-phase load to the two-phase branch in the three-phase bridge circuit, and the main switch tubes of the two-phase branch are connected in parallel with the resonant capacitor. The present invention can switch to supply power to a three-phase load or a two-phase load, and the switching loss is small during high-frequency operation, and the working efficiency of the inverter is high.

Description

Technical Field

[0001] The present invention relates to the technical field of inverters, and in particular to a multifunctional inverter circuit, a control method, a compressor and an air conditioner. Background Art

[0002] The three-phase full-bridge inverter is a key device in air-conditioning compressor control. Figure 1 As shown, in the existing topology, the three-phase full-bridge inverter has two obvious defects: 1. The inverter works in the conventional switching frequency mode to supply power to the three-phase AC load, with relatively simple functions and low practicality; 2. The inverter is in a hard switching state. With the increase of the switching frequency, the switching loss increases significantly, which seriously affects the improvement of the inverter efficiency.

[0003] Currently, soft switching technology has emerged that can reduce various adverse effects of inverters due to high frequency and large size. The existing soft switching topology has a large number of auxiliary components, and the switching losses of the auxiliary components are large when working at high frequency, which needs to be further improved. Summary of the invention

[0004] In order to solve the defect of the existing inverter circuit having a single function, the present invention proposes a multifunctional inverter circuit, a control method, a compressor and an air conditioner.

[0005] The technical solution adopted by the present invention is to design a multifunctional inverter circuit, including:

[0006] Three-phase bridge circuit, each phase branch is equipped with two sets of upper and lower main switch tubes;

[0007] A three-phase load is connected to each phase branch of a three-phase bridge circuit;

[0008] A two-phase load is connected in series with a first switch and then connected to two-phase branches in a three-phase bridge circuit, and the remaining one-phase branch in the three-phase bridge circuit is a regulating branch;

[0009] The control module controls the on-off state of the first switch and the regulating branch to switch on the three-phase load or the two-phase load.

[0010] Preferably, when the first switch is turned on and the regulating branch is turned off, the two-phase load is turned on and the three-phase load is turned off; when the first switch is turned off, the three-phase load is turned on and the two-phase load is turned off.

[0011] Preferably, when the three-phase bridge circuit works in a high-frequency mode, the control module turns on the first switch and disconnects the regulating branch; when the three-phase bridge circuit works in an industrial frequency mode, the control module disconnects the first switch.

[0012] The main switch tube of each phase branch is connected in parallel with a main diode, the anode of the main diode is connected to the emitter of the main switch tube, and the cathode of the main diode is connected to the collector of the main switch tube.

[0013] Preferably, the multifunctional inverter circuit further includes: a soft switching auxiliary circuit and a resonant capacitor, wherein the soft switching auxiliary circuit is connected in parallel with the two-phase load to two-phase branches in the three-phase bridge circuit, and the main switch tubes of the two-phase branches are both connected in parallel with the resonant capacitor.

[0014] In one embodiment, one of the two phase branches is provided with an upper bridge main switch tube V1 and a lower bridge main switch tube V3, and the other phase branch is provided with an upper bridge main switch tube V2 and a lower bridge main switch tube V4, the upper bridge main switch tube V1 is connected with a parallel resonant capacitor Cr1, the upper bridge main switch tube V2 is connected with a parallel resonant capacitor Cr2, the lower bridge main switch tube V3 is connected with a parallel resonant capacitor Cr3, and the lower bridge main switch tube V4 is connected with a parallel resonant capacitor Cr4. The soft switch auxiliary circuit includes: an auxiliary switch tube Sa, an inductor L1 and an auxiliary switch tube Sb, the inductor L1 is connected in series with the collector of the auxiliary switch tube Sa and the collector of the auxiliary switch tube Sb, the emitter of the auxiliary switch tube Sa is connected between the upper bridge main switch tube V1 and the lower bridge main switch tube V3, and the emitter of the auxiliary switch tube Sb is connected between the upper bridge main switch tube V2 and the lower bridge main switch tube V4.

[0015] Preferably, each auxiliary switch tube is connected in parallel with an auxiliary diode, the anode of the auxiliary diode is connected to the emitter of the auxiliary switch tube, and the cathode of the auxiliary diode is connected to the collector of the auxiliary switch tube.

[0016] The present invention also proposes a control method for the multifunctional inverter circuit, the control method comprising:

[0017] After the auxiliary switch tube Sa is turned on for a first period of time, the upper bridge main switch tube V2 and the lower bridge main switch tube V3 are turned off;

[0018] Detect the actual voltage of the resonant capacitor Cr2 and / or the resonant capacitor Cr3 to determine whether the actual voltage reaches the power supply voltage Ud of the three-phase bridge circuit. If so, turn on the upper bridge main switch tube V1 and the lower bridge main switch tube V4 for a second time period, and then turn on the auxiliary switch tube Sb;

[0019] After the auxiliary switch tube Sb is turned on for a third period of time, the upper bridge main switch tube V1 and the lower bridge main switch tube V4 are turned off;

[0020] Detect the actual voltage of the resonant capacitor Cr1 and / or the resonant capacitor Cr4 to determine whether the actual voltage reaches the power supply voltage Ud of the three-phase bridge circuit. If so, turn on the upper bridge main switch tube V2 and the lower bridge main switch tube V3 for a fourth period of time, and then turn on the auxiliary switch tube Sa.

[0021] The present invention also provides a compressor using the multifunctional inverter circuit.

[0022] The present invention also provides an air conditioner having the compressor.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] 1. The inverter circuit can switch to supply power to two-phase loads or three-phase loads, with multiple functions and flexible use;

[0025] 2. The soft switching auxiliary circuit is connected in parallel with the load of the inverter. Through the function of the soft switching auxiliary circuit and the resonant capacitor, the switching loss during high-frequency operation is effectively reduced, and the working efficiency of the inverter is improved;

[0026] 3. The number of auxiliary circuit devices is small, the structure is simple, and there are no auxiliary devices connected in series on the main power transmission channel, so the switching loss of the auxiliary devices is small. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present invention is described in detail below with reference to the embodiments and accompanying drawings, wherein:

[0028] Figure 1 It is a connection diagram of an existing inverter circuit;

[0029] Figure 2 It is a connection diagram of the multifunctional inverter circuit in the present invention. DETAILED DESCRIPTION

[0030] like Figure 2 As shown, the multifunctional inverter circuit proposed in the present invention includes: a three-phase bridge circuit, a three-phase load, a two-phase load and a control module. The three-phase bridge circuit is provided with three-phase branches. Both ends of the three-phase bridge circuit are connected to a DC power supply, and the power supply voltage of the DC power supply is Ud. Each phase branch is provided with two groups of upper and lower main switch tubes, the first phase branch is provided with an upper bridge main switch tube V1 and a lower bridge main switch tube V3, the second phase branch is provided with an upper bridge main switch tube V2 and a lower bridge main switch tube V4, the third phase branch is provided with an upper bridge main switch tube V5 and a lower bridge main switch tube V6, the collectors of the three upper bridge main switch tubes are connected to the positive electrode of the DC power supply, the emitters of the three lower bridge main switch tubes are connected to the negative electrode of the DC power supply, the upper bridge main switch tube V1 is connected in parallel with a main diode D1, the upper bridge main switch tube V2 is connected in parallel with a main diode D2, the lower bridge main switch tube V3 is connected in parallel with a main diode D3, the lower bridge main switch tube V4 is connected in parallel with a main diode D4, the upper bridge main switch tube V5 is connected in parallel with a main diode D5, and the lower bridge main switch tube V6 is connected in parallel with a main diode D6, the positive electrode of the main diode is connected to the emitter of the corresponding main switch tube, the negative electrode of the main diode is connected to the collector of the corresponding main switch tube, and the main switch tube is protected by the main diode.

[0031] The midpoints of the three-phase branches are respectively connected to the three-phase loads, the midpoints of the first phase branch and the second phase branch are respectively connected to the two-phase loads, and a first switch K1 is connected in series between the two-phase load and the first phase branch. The midpoint here refers to the position between the upper bridge main switch tube and the lower bridge main switch tube in each phase branch, and the remaining third phase branch in the three-phase bridge circuit is a regulating branch.

[0032] The base of each main switch tube and the first switch K1 are connected to the control module. The control module controls the on-off state of the first switch and each phase branch. At the same time, the upper and lower bridge main switch tubes in the same phase branch cannot be turned on at the same time. When adjusting the on-off state of the first switch and the regulating branch, the three-phase bridge circuit can be switched to power a three-phase load or a two-phase load.

[0033] In more detail, when the three-phase bridge circuit works in high-frequency mode, the control module turns on the first switch, turns off the upper bridge main switch tube V5 and the lower bridge main switch tube V6, at this time the regulating branch is disconnected, and the three-phase bridge circuit is equivalent to a single-phase full-bridge inverter circuit supplying power to a two-phase load. When the three-phase bridge circuit works in the power frequency mode, i.e., the normal working mode, the control module turns off the first switch, and the three-phase bridge circuit supplies power to the three-phase load.

[0034] The multifunctional inverter circuit also includes: a soft switching auxiliary circuit and a resonant capacitor. The soft switching auxiliary circuit is connected in parallel with the two-phase load to the first phase branch and the second phase branch. The main switch tubes of the two-phase branches are connected in parallel with resonant capacitors, namely, the upper bridge main switch tube V1 parallel resonant capacitor Cr1, the upper bridge main switch tube V2 parallel resonant capacitor Cr2, the lower bridge main switch tube V3 parallel resonant capacitor Cr3, and the lower bridge main switch tube V4 parallel resonant capacitor Cr4.

[0035] like Figure 2 As shown, in a preferred embodiment, the soft switch auxiliary circuit includes: an auxiliary switch tube Sa, an inductor L1 and an auxiliary switch tube Sb, the inductor L1 is connected in series with the collector of the auxiliary switch tube Sa and the collector of the auxiliary switch tube Sb, the emitter of the auxiliary switch tube Sa is connected between the upper bridge main switch tube V1 and the lower bridge main switch tube V3, and the emitter of the auxiliary switch tube Sb is connected between the upper bridge main switch tube V2 and the lower bridge main switch tube V4. The auxiliary switch tube Sa is connected in parallel with an auxiliary diode D7, and the auxiliary switch tube Sb is connected in parallel with an auxiliary diode D8, the positive electrode of the auxiliary diode is connected to the emitter of the corresponding auxiliary switch tube, and the negative electrode of the auxiliary diode is connected to the collector of the corresponding auxiliary switch tube, and the auxiliary diode is used to protect the auxiliary switch tube.

[0036] The present invention also proposes a control method for the multifunctional inverter circuit, the control method comprising:

[0037] At time TI, the auxiliary switch tube Sa is turned on. Since the inductor L1 limits the current rising speed when the auxiliary switch tube Sa is turned on, the auxiliary switch tube Sa is in a zero-current soft-on state when turned on. After the auxiliary switch tube Sa is turned on for the first time, the upper bridge main switch tube V2 and the lower bridge main switch tube V3 are turned off at time T2. The resonant capacitor Cr2 and the resonant capacitor Cr3 limit the voltage change speed when the upper bridge main switch tube V2 and the lower bridge main switch tube V3 are turned off. Therefore, the upper bridge main switch tube V2 and the lower bridge main switch tube V3 are in a zero-voltage turn-off state when they are turned off. The circuit enters a dead zone state, and the inductor L1 and the resonant capacitors Cr1 to Cr4 begin to resonate. The resonant capacitors Cr1 and Cr4 discharge, and the resonant capacitors Cr2, Cr3 and the inductor L1 are charged.

[0038] Detect the actual voltage of the resonant capacitor Cr2 and / or the resonant capacitor Cr3, and determine whether the actual voltage reaches the power supply voltage Ud of the three-phase bridge circuit. If so, the resonance process stops, and the upper bridge main switch tube V1 and the lower bridge main switch tube V4 are turned on, so that the upper bridge main switch tube V1 and the lower bridge main switch tube V4 can be turned on at zero voltage. After the upper bridge main switch tube V1 and the lower bridge main switch tube V4 are turned on for a second time, the auxiliary switch tube Sb is turned on at time T3. Under the limitation of the inductor L1, the auxiliary switch tube Sb realizes zero current turning on;

[0039] After the auxiliary switch tube Sb is turned on for the third time, the upper bridge main switch tube V1 and the lower bridge main switch tube V4 are turned off at time T4. The resonant capacitor Cr1 and the resonant capacitor Cr4 limit the voltage change speed when they are turned off. Therefore, the upper bridge main switch tube V1 and the lower bridge main switch tube V4 are in a zero voltage soft turn-off state when they are turned off. The circuit enters a dead zone state, and the inductor L1 and the resonant capacitors Cr1 to Cr4 begin to resonate. The resonant capacitors Cr2 and Cr3 are discharged, and the resonant capacitors Cr1, Cr4 and the inductor L1 are charged.

[0040] Detect the actual voltage of the resonant capacitor Cr1 and / or the resonant capacitor Cr4, and determine whether the actual voltage reaches the power supply voltage Ud of the three-phase bridge circuit. If so, the resonance process stops, and the upper bridge main switch tube V2 and the lower bridge main switch tube V3 are turned on, so that the upper bridge main switch tube V2 and the lower bridge main switch tube V3 can be turned on at zero voltage. After the upper bridge main switch tube V2 and the lower bridge main switch tube V3 are turned on for the fourth period of time, the auxiliary switch tube Sa is turned on at time T5.

[0041] The present invention also provides a compressor using the multifunctional inverter circuit and an air conditioner having the compressor.

[0042] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A multifunctional inverter circuit, characterized in that: include: Three-phase bridge circuit, each phase branch is equipped with two sets of upper and lower main switch tubes; A three-phase load connected to each phase branch of the three-phase bridge circuit; A two-phase load, connected in series with a first switch and then connected to two-phase branches in the three-phase bridge circuit, wherein the remaining one-phase branch in the three-phase bridge circuit is a regulating branch; A control module, controlling the on / off state of the first switch and the regulating branch to switch on the three-phase load or the two-phase load; A soft switch auxiliary circuit and a resonant capacitor, wherein the soft switch auxiliary circuit is connected in parallel with the two-phase load to two-phase branches in the three-phase bridge circuit, and the main switch tubes of the two-phase branches are both connected in parallel with the resonant capacitor.

2. The multifunctional inverter circuit according to claim 1, characterized in that: When the first switch is turned on and the regulating branch is turned off, the two-phase load is turned on and the three-phase load is turned off; when the first switch is turned off, the three-phase load is turned on and the two-phase load is turned off.

3. The multifunctional inverter circuit according to claim 2, characterized in that: When the three-phase bridge circuit works in a high-frequency mode, the control module turns on the first switch and turns off the regulating branch; when the three-phase bridge circuit works in an industrial frequency mode, the control module turns off the first switch.

4. The multifunctional inverter circuit according to claim 1, characterized in that: The main switch tube of each phase branch is connected in parallel with a main diode, the anode of the main diode is connected to the emitter of the main switch tube, and the cathode of the main diode is connected to the collector of the main switch tube.

5. The multifunctional inverter circuit according to claim 1, characterized in that: One of the two-phase branches is provided with an upper bridge main switch tube V1 and a lower bridge main switch tube V3, and the other phase branch is provided with an upper bridge main switch tube V2 and a lower bridge main switch tube V4, the upper bridge main switch tube V1 is connected with a parallel resonant capacitor Cr1, the upper bridge main switch tube V2 is connected with a parallel resonant capacitor Cr2, the lower bridge main switch tube V3 is connected with a parallel resonant capacitor Cr3, and the lower bridge main switch tube V4 is connected with a parallel resonant capacitor Cr4; The soft switch auxiliary circuit includes: an auxiliary switch tube Sa, an inductor L1 and an auxiliary switch tube Sb, the inductor L1 is connected in series with the collector of the auxiliary switch tube Sa and the collector of the auxiliary switch tube Sb, the emitter of the auxiliary switch tube Sa is connected between the upper bridge main switch tube V1 and the lower bridge main switch tube V3, and the emitter of the auxiliary switch tube Sb is connected between the upper bridge main switch tube V2 and the lower bridge main switch tube V4.

6. The multifunctional inverter circuit according to claim 5, characterized in that: Each auxiliary switch tube is connected in parallel with an auxiliary diode, the anode of the auxiliary diode is connected to the emitter of the auxiliary switch tube, and the cathode of the auxiliary diode is connected to the collector of the auxiliary switch tube.

7. A control method for a multifunctional inverter circuit, characterized in that: The multifunctional inverter circuit adopts the multifunctional inverter circuit as claimed in claim 5 or 6; The control method comprises: After the auxiliary switch tube Sa is turned on for a first period of time, the upper bridge main switch tube V2 and the lower bridge main switch tube V3 are turned off; Detecting the actual voltage of the resonant capacitor Cr2 and / or the resonant capacitor Cr3, determining whether the actual voltage reaches the power supply voltage Ud of the three-phase bridge circuit, and if so, turning on the upper bridge main switch tube V1 and the lower bridge main switch tube V4 for a second time period, and then turning on the auxiliary switch tube Sb; After the auxiliary switch tube Sb is turned on for a third period of time, the upper bridge main switch tube V1 and the lower bridge main switch tube V4 are turned off; Detect the actual voltage of the resonant capacitor Cr1 and / or the resonant capacitor Cr4 to determine whether the actual voltage reaches the power supply voltage Ud of the three-phase bridge circuit. If so, turn on the upper bridge main switch tube V2 and the lower bridge main switch tube V3 for a fourth period of time, and then turn on the auxiliary switch tube Sa.

8. A compressor, characterized in that: The compressor adopts the multifunctional inverter circuit as described in any one of claims 1 to 6.

9. An air conditioner, characterized in that: The air conditioner has the compressor according to claim 8.

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