Three-phase motor two-phase space voltage vector control circuit and control method

Abstract

The application belongs to the technical field of AC-DC-AC frequency converter, and particularly discloses a three-phase motor two-phase space voltage vector control circuit and a control method thereof. The application adopts two-phase independent filtering inversion, directly connects the reference phase of the power supply and the load, and connects to the midpoint of the bus capacitor of two groups of frequency conversion circuits, proposes to perform space voltage modulation by using voltage eight vectors, reduces the cost of the frequency converter, and completes normal frequency conversion and speed regulation of the motor under two-phase control. Torque pulsation and power switching devices are reduced, element faults are less, and production cost and maintenance cost are greatly reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of three-phase AC-DC-AC frequency conversion device, it is a kind of three-phase motor two-phase space voltage vector control circuit and control method. BACKGROUND

[0002] At present, traditional voltage source type AC-DC-AC three-phase six-switch frequency converter has been widely applied in the speed regulation process of three-phase asynchronous motor, using the characteristics of IGBT, traditional topology structure can meet the speed regulation requirement in most cases.Based on this classic topology structure, further derived three-phase four-switch topology structure for reducing the number of IGBT used.Because still with voltage source type inverter as basic structure, three-phase four-switch speed regulation method can be improved by conventional control strategy.This technology's biggest feature is to control stator flux linkage and torque directly, and they do not interfere with each other, so the current closed loop part is saved, and therefore better dynamic performance can be obtained.Especially in high-power unit, if the stator flux linkage is controlled in hexagon, due to the large inertial potential of the unit, the switching frequency can be reduced, and thus the loss of components can be reduced.

[0003] When connecting one phase of the load to the bus power midpoint to form the topology structure of four-switch inverter, the bus supply voltage is reduced by half, and different control methods are greatly affected, which is also the main reason why four-switch inverter is mainly used as a fault-tolerant and short-term coping strategy.The reduction of DC power voltage in the process of sinusoidal pulse width modulation makes the effective value of output AC power reduce to 1 / 2;In the process of space voltage vector pulse width modulation: (1) due to the reduction of the number of switching tubes, three-phase four-switch inverter can only output four basic voltage vectors with a phase difference of 90°, compared with the traditional six-switch operation mode, the space voltage vector sector is reduced from six to four, lacking zero voltage vector, the amplitude of voltage vector is asymmetric, the switching of voltage vector in the inverter process is not smooth, and the output of the inverter is not as fine as the six-switch, resulting in large motor torque ripple;2) the amplitude of output voltage vector is reduced to 1 / 2, which leads to a sharp reduction of motor output torque and a reduction of load carrying capacity, so the performance of four-switch speed regulation is greatly reduced compared with traditional frequency converter.Therefore, traditional four-switch inverter control can effectively reduce the use of fully controlled devices, but can only be used as a coping method when six-switch inverter fails.In order to improve four-switch inverter technology, two-phase frequency conversion control is applied to normal speed regulation of motor, and then the present application is studied--three-phase motor two-phase frequency conversion control circuit based on thyristor and IGBT hybrid. SUMMARY

[0004] The present application aims to provide a kind of three-phase motor two-phase space voltage vector control circuit and method, for the problem of large torque ripple in the control of three-phase asynchronous motor controlled by four-switch, based on eight vectors, which can better reduce the torque ripple of four-switch three-phase asynchronous motor.

[0005] The technical scheme of the present application is as follows:

[0006] The three-phase motor two-phase space voltage vector control circuit is characterized in that it comprises a three-phase power supply, a rectifier circuit, a DC bus circuit, an inverter circuit and a three-phase asynchronous motor, the three-phase power supply, the rectifier circuit, the DC bus circuit, the inverter circuit and the three-phase asynchronous motor are sequentially connected, the output end of the DC bus circuit is connected with the input end of the inverter circuit, the midpoint of the capacitor of the DC bus circuit is connected with the W phase of the three-phase asynchronous motor, and the output end of the inverter circuit is connected with the U phase and the V phase of the three-phase asynchronous motor.

[0007] The rectifier circuit is a diode uncontrolled rectifier circuit, that is, a rectifier circuit composed of six diodes in the prior art.

[0008] The DC bus circuit comprises a first capacitor C1 and a second capacitor C2, the first capacitor C1 and the second capacitor C2 are connected in series, and the midpoint of the first capacitor C1 and the second capacitor C2 is connected with the W phase of the three-phase asynchronous motor.

[0009] The inverter circuit comprises a U-phase inverter circuit and a V-phase inverter circuit.

[0010] The U-phase inverter circuit comprises a first thyristor VT1, a second thyristor VT2, an IGBT1, a first diode D1, a second diode D2, a third diode D3, a fourth diode D4 and a third capacitor C3.

[0011] The cathode of the first thyristor VT1 is connected with the collector of the IGBT1 and the anode of the first diode D1 respectively, and the anode of the first thyristor VT1 is connected with the cathode of the first diode D1.

[0012] The anode of the second thyristor VT2 is connected with the emitter of the IGBT1 and the cathode of the second diode D2 respectively, and the cathode of the second thyristor VT2 is connected with the anode of the second diode D2.

[0013] The third capacitor C3 is connected in parallel between the collector and the emitter of the IGBT1, and the third diode D3 and the fourth diode D4 connected in series in forward direction are also connected in parallel between the collector and the emitter of the IGBT1.

[0014] The U phase of the three-phase asynchronous motor is connected between the third diode D3 and the fourth diode D4.

[0015] The V-phase inverter circuit comprises a third thyristor VT3, a fourth thyristor VT4, an IGBT2, a fifth diode D5, a sixth diode D6, a seventh diode D7, an eighth diode D8 and a fourth capacitor C4.

[0016] The cathode of the third thyristor VT3 is connected with the collector of the IGBT2 and the anode of the fifth diode D5 respectively, and the anode of the third thyristor VT3 is connected with the cathode of the fifth diode D5;

[0017] The anode of the fourth thyristor VT4 is connected with the emitter of the IGBT2 and the cathode of the sixth diode D6 respectively, and the cathode of the fourth thyristor VT4 is connected with the anode of the sixth diode D6;

[0018] The fourth capacitor C4 is connected in parallel between the collector and the emitter of the IGBT2, and the seventh diode D7 and the eighth diode D8 are connected in series in parallel between the collector and the emitter of the IGBT2;

[0019] The V phase of the three-phase asynchronous motor is connected between the seventh diode D7 and the eighth diode D8.

[0020] Based on the above-mentioned two-phase space voltage vector control circuit of the three-phase motor, the control method of the control circuit is given, and the method is as follows:

[0021] Before the starting process, the counterclockwise is defined as the positive rotation, and the Hall sensor of the three-phase asynchronous motor detects the rotor position of the motor, according to the rotor position, the corresponding voltage vector is selected for control, and different conduction states of the switching device are realized.

[0022] The specific method is as follows:

[0023] An alpha-beta coordinate system is established, the A phase voltage vector of the three-phase asynchronous motor is defined in the 90° direction, the B phase voltage vector is defined in the-150° direction, and the C phase voltage vector is defined in the-30° direction, so that the voltage vectors of all possible conduction states are eight, which are defined as voltage vector U1, voltage vector U2, voltage vector U3, voltage vector U4, voltage vector U5, voltage vector U6, voltage vector U7 and voltage vector U8, wherein U1 is defined as the voltage vector when the IGBT2 and the fourth thyristor VT4 are simultaneously turned on, U2 is defined as the voltage vector when the IGBT1 and the first thyristor VT1 and the IGBT2 and the fourth thyristor VT4 are simultaneously turned on, U3 is defined as the voltage vector when the IGBT1 and the first thyristor VT1 are simultaneously turned on, U4 is defined as the voltage vector when the IGBT1 and the first thyristor VT1 and the IGBT2 and the third thyristor VT3 are simultaneously turned on, U5 is defined as the voltage vector when the IGBT2 and the third thyristor VT3 are simultaneously turned on, U6 is defined as the voltage vector when the IGBT1 and the second thyristor VT2 and the IGBT2 and the third thyristor VT3 are simultaneously turned on, U7 is defined as the voltage vector when the IGBT1 and the second thyristor VT2 are simultaneously turned on, and U8 is defined as the voltage vector when the IGBT1 and the second thyristor VT2 and the IGBT2 and the fourth thyristor VT4 are simultaneously turned on.

[0024] The states of the first thyristor VT1, the second thyristor VT2, the third thyristor VT3 and the fourth thyristor VT4 are recorded as a four-bit code (abcd), a, b, c and d correspond to the first thyristor VT1, the second thyristor VT2, the third thyristor VT3 and the fourth thyristor VT4 in turn, and the value 1 represents that the corresponding thyristor is in the on state, and the value 0 represents that the corresponding thyristor is in the blocking state, so that the voltage vectors U1, U2, U3, U4, U5, U6, U7 and U8 are U1 (0001), U2 (1001), U3 (1000), U4 (1010), U5 (0010), U6 (0110), U7 (0100) and U8 (0101) in turn.

[0025] When the position of the rotor is detected to be between 300° and 0°, the voltage vector U1 is selected; when the position of the rotor is detected to be between 0° and 30°, the voltage vector U2 is selected; when the position of the rotor is detected to be between 30° and 90°, the voltage vector U3 is selected; when the position of the rotor is detected to be between 90° and 120°, the voltage vector U4 is selected; when the position of the rotor is detected to be between 120° and 150°, the voltage vector U5 is selected; when the position of the rotor is detected to be between 150° and 210°, the voltage vector U6 is selected; when the position of the rotor is detected to be between 210° and 270°, the voltage vector U7 is selected; and when the position of the rotor is detected to be between 270° and 300°, the voltage vector U8 is selected.

[0026] Compared with the prior art, the technical scheme of the present application has the following beneficial effects:

[0027] The present application only needs four switches (i.e., two thyristors in each phase of two phases share one IGBT instead of two IGBTs) for frequency conversion and speed regulation. For inverter output, the midpoint of the DC bus circuit capacitor C1 and the capacitor C2 is taken as a reference point as the motor C phase output. With respect to the motor, a symmetrical three-phase waveform is actually formed, a rotating magnetic field is generated, and the motor can be driven to rotate. The three-phase four-switch three-phase asynchronous motor space voltage vector control strategy uses fewer main switching devices than the traditional frequency conversion circuit, and simultaneously realizes voltage regulation and frequency conversion and speed regulation. Compared with other four-switch three-phase asynchronous motor control methods, the present application uses eight synthesized space voltage vectors for control, and two additional space voltage vectors can well suppress the torque ripple of the motor. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 It is a topology diagram of the two-phase space voltage vector control circuit of the three-phase motor of the present application.

[0029] Figure 2 Fig. 8 is a diagram of eight voltage vectors for the control method of the present application. DETAILED DESCRIPTION

[0030] The present application will be further described in details with reference to specific embodiments, but the embodiments of the present application include but are not limited to the scope represented by the following embodiments. The shape and size can be changed as needed.

[0031] Referring to Figure 1 The application discloses a two-phase space voltage vector control circuit of a three-phase motor based on a thyristor and IGBT mixture, which comprises a three-phase power supply, a rectifier circuit, a DC bus circuit, an inverter circuit and a three-phase asynchronous motor, the three-phase power supply, the rectifier circuit, the DC bus circuit, the inverter circuit and the three-phase asynchronous motor are sequentially connected, the output end of the DC bus circuit is connected with the input end of the inverter circuit, the capacitor midpoint of the DC bus circuit is connected with the W phase of the three-phase asynchronous motor, and the output end of the inverter circuit is connected with the U phase and the V phase of the three-phase asynchronous motor.

[0032] The rectifier circuit is a diode uncontrolled rectifier circuit, that is, a rectifier circuit composed of six diodes.

[0033] The DC bus circuit comprises a first capacitor C1 and a second capacitor C2, the first capacitor C1 and the second capacitor C2 are connected in series, and the midpoint of the first capacitor C1 and the second capacitor C2 is connected with the W phase of the three-phase asynchronous motor.

[0034] The inverter circuit comprises a U-phase inverter circuit and a V-phase inverter circuit.

[0035] The U-phase inverter circuit comprises a first thyristor VT1, a second thyristor VT2, an IGBT1, a first diode D1, a second diode D2, a third diode D3, a fourth diode D4 and a third capacitor C3.

[0036] The cathode of the first thyristor VT1 is connected with the collector of the IGBT1 and the anode of the first diode D1 respectively, the anode of the first thyristor VT1 is connected with the cathode of the first diode D1,

[0037] The anode of the second thyristor VT2 is connected with the emitter of the IGBT1 and the cathode of the second diode D2 respectively, the cathode of the second thyristor VT2 is connected with the anode of the second diode D2,

[0038] The third capacitor C3 is connected in parallel between the collector and the emitter of the IGBT1, and the U phase of the three-phase asynchronous motor is connected between the third diode D3 and the fourth diode D4,

[0039] The V-phase inverter circuit comprises a third thyristor VT3, a fourth thyristor VT4, an IGBT2, a fifth diode D5, a sixth diode D6, a seventh diode D7, an eighth diode D8 and a fourth capacitor C4,

[0040] The cathode of the third thyristor VT3 is connected with the collector of the IGBT2 and the anode of the fifth diode D5 respectively, and the anode of the third thyristor VT3 is connected with the cathode of the fifth diode D5,

[0041] The anode of the fourth thyristor VT4 is connected with the emitter of the IGBT2 and the cathode of the sixth diode D6 respectively, and the cathode of the fourth thyristor VT4 is connected with the anode of the sixth diode D6,

[0042] The fourth capacitor C4 is connected in parallel between the collector and the emitter of the IGBT2, and the V-phase of the three-phase asynchronous motor is connected between the seventh diode D7 and the eighth diode D8.

[0043] A control method of the three-phase motor two-phase space voltage vector control circuit is provided, and the method comprises the following steps:

[0044] Before the starting process, the counterclockwise is defined as the positive rotation, and the Hall sensor of the three-phase asynchronous motor detects the rotor position of the motor, and according to the rotor position, the corresponding voltage vector is selected for control, so as to realize the different conduction states of the switching devices.

[0045] The method further comprises:

[0046] An alpha-beta coordinate system is established, and the A-phase voltage vector of the three-phase asynchronous motor is defined in the 90° direction, the B-phase voltage vector is defined in the -150° direction, and the C-phase voltage vector is defined in the -30° direction, so that the voltage vectors of all possible conduction states are eight, which are defined as voltage vector U1, voltage vector U2, voltage vector U3, voltage vector U4, voltage vector U5, voltage vector U6, voltage vector U7 and voltage vector U8, wherein U1 is defined as the voltage vector when IGBT2 and the fourth thyristor VT4 are simultaneously turned on, U2 is defined as the voltage vector when IGBT1 and the first thyristor VT1 and IGBT2 and the fourth thyristor VT4 are simultaneously turned on, U3 is defined as the voltage vector when IGBT1 and the first thyristor VT1 are simultaneously turned on, U4 is defined as the voltage vector when IGBT1 and the first thyristor VT1 and IGBT2 and the third thyristor VT3 are simultaneously turned on, U5 is defined as the voltage vector when IGBT2 and the third thyristor VT3 are simultaneously turned on, U6 is defined as the voltage vector when IGBT1 and the second thyristor VT2 and IGBT2 and the third thyristor VT3 are simultaneously turned on, U7 is defined as the voltage vector when IGBT1 and the second thyristor VT2 are simultaneously turned on, and U8 is defined as the voltage vector when IGBT1 and the second thyristor VT2 and IGBT2 and the fourth thyristor VT4 are simultaneously turned on.

[0047] When the position of the rotor is detected to be between 300° and 0°, the voltage vector U1 is selected, when the position of the rotor is detected to be between 0° and 30°, the voltage vector U2 is selected, when the position of the rotor is detected to be between 30° and 90°, the voltage vector U3 is selected, when the position of the rotor is detected to be between 90° and 120°, the voltage vector U4 is selected, when the position of the rotor is detected to be between 120° and 150°, the voltage vector U5 is selected, when the position of the rotor is detected to be between 150° and 210°, the voltage vector U6 is selected, when the position of the rotor is detected to be between 210° and 270°, the voltage vector U7 is selected, and when the position of the rotor is detected to be between 270° and 300°, the voltage vector U8 is selected.

[0048] The reference phase of the power supply and the load is improved in the topology structure, two-phase independent filter inverter is adopted, the reference phase of the power supply and the load is directly connected and connected to the midpoint of the bus capacitor of the two groups of frequency conversion circuits, voltage eight vectors are used for space voltage modulation, the cost of the frequency converter is reduced, and normal frequency conversion speed regulation of the motor under two-phase control is completed.

[0049] The content of the application is not limited to the examples, and any equivalent transformation of the technical scheme of the application by a person skilled in the art by reading the specification of the application is covered by the claims of the application.

Claims

1. A control method of a three-phase motor two-phase space voltage vector control circuit, characterized by, The method is: Before the starting process, the clockwise direction is defined as the positive rotation, the Hall sensor of the three-phase asynchronous motor detects the rotor position of the motor, according to the rotor position, the corresponding voltage vector is selected for control, and different conduction states of the switching device are realized; An alpha-beta coordinate system is established, the A-phase voltage vector of the three-phase asynchronous motor is defined in the 90° direction, the B-phase voltage vector is defined in the-150° direction, and the C-phase voltage vector is defined in the-30° direction, so that the voltage vectors of all possible conduction states are eight, which are defined as voltage vector U1, voltage vector U2, voltage vector U3, voltage vector U4, voltage vector U5, voltage vector U6, voltage vector U7 and voltage vector U8, wherein U1 is defined as the voltage vector when IGBT2 and the fourth thyristor VT4 are simultaneously turned on; U2 is defined as the voltage vector when IGBT1 and the first thyristor VT1, IGBT2 and the fourth thyristor VT4 are simultaneously turned on; U3 is defined as the voltage vector when IGBT1 and the first thyristor VT1 are simultaneously turned on; U4 is defined as the voltage vector when IGBT1 and the first thyristor VT1, IGBT2 and the third thyristor VT3 are simultaneously turned on; U5 is defined as the voltage vector when IGBT2 and the third thyristor VT3 are simultaneously turned on; U6 is defined as the voltage vector when IGBT1 and the second thyristor VT2, IGBT2 and the third thyristor VT3 are simultaneously turned on; U7 is defined as the voltage vector when IGBT1 and the second thyristor VT2 are simultaneously turned on; U8 is defined as the voltage vector when IGBT1 and the second thyristor VT2, IGBT2 and the fourth thyristor VT4 are simultaneously turned on; When the position of the rotor is detected to be between 300° and 0°, voltage vector U1 is selected; when the position of the rotor is detected to be between 0° and 30°, voltage vector U2 is selected; when the position of the rotor is detected to be between 30° and 90°, voltage vector U3 is selected; when the position of the rotor is detected to be between 90° and 120°, voltage vector U4 is selected; when the position of the rotor is detected to be between 120° and 150°, voltage vector U5 is selected; when the position of the rotor is detected to be between 150° and 210°, voltage vector U6 is selected; when the position of the rotor is detected to be between 210° and 270°, voltage vector U7 is selected; when the position of the rotor is detected to be between 270° and 300°, voltage vector U8 is selected; The control circuit based on the above control method comprises: a three-phase power supply, a rectifier circuit, a DC bus circuit, an inverter circuit and a three-phase asynchronous motor, the three-phase power supply, the rectifier circuit, the DC bus circuit, the inverter circuit and the three-phase asynchronous motor are connected in sequence, the output end of the DC bus circuit is connected with the input end of the inverter circuit, the capacitor midpoint of the DC bus circuit is connected with the W phase of the three-phase asynchronous motor, and the output end of the inverter circuit is connected with the U and V phases of the three-phase asynchronous motor; The inverter circuit comprises a U-phase inverter circuit and a V-phase inverter circuit; The U-phase inverter circuit comprises a first thyristor VT1, a second thyristor VT2, an IGBT1, a first diode D1, a second diode D2, a third diode D3, a fourth diode D4 and a third capacitor C3. The cathode of the first thyristor VT1 is connected with the collector of the IGBT1 and the anode of the first diode D1 respectively, the anode of the first thyristor VT1 is connected with the cathode of the first diode D1, The anode of the second thyristor VT2 is connected with the emitter of the IGBT1 and the cathode of the second diode D2 respectively, the cathode of the second thyristor VT2 is connected with the anode of the second diode D2, The third capacitor C3 is connected in parallel between the collector and the emitter of the IGBT1, and the U-phase of the three-phase asynchronous motor is connected between the third diode D3 and the fourth diode D4. The V-phase inverter circuit comprises a third thyristor VT3, a fourth thyristor VT4, an IGBT2, a fifth diode D5, a sixth diode D6, a seventh diode D7, an eighth diode D8 and a fourth capacitor C4. The cathode of the third thyristor VT3 is connected with the collector of the IGBT2 and the anode of the fifth diode D5 respectively, the anode of the third thyristor VT3 is connected with the cathode of the fifth diode D5, The anode of the fourth thyristor VT4 is connected with the emitter of the IGBT2 and the cathode of the sixth diode D6 respectively, the cathode of the fourth thyristor VT4 is connected with the anode of the sixth diode D6, The fourth capacitor C4 is connected in parallel between the collector and the emitter of the IGBT2, and the V-phase of the three-phase asynchronous motor is connected between the seventh diode D7 and the eighth diode D8.

2. The control method of a three-phase motor two-phase space voltage vector control circuit according to claim 1, characterized by: The rectifier circuit is a diode uncontrolled rectifier circuit, that is, a rectifier circuit composed of six diodes.

3. The control method of a three-phase motor two-phase space voltage vector control circuit according to claim 1, characterized by: The direct-current bus circuit comprises a first capacitor C1 and a second capacitor C2, the first capacitor C1 and the second capacitor C2 are connected in series, and the midpoint of the first capacitor C1 and the second capacitor C2 is connected with the W-phase of the three-phase asynchronous motor.

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