Low-harmonic driving topology and control method of open-winding high-speed motor

Abstract

The application discloses a kind of open-winding high-speed motor low harmonic drive topological structures and control methods, this topological structure is based on the structure of open-winding motor, by increasing small-power high switching frequency harmonic compensation converter, high-frequency small voltage vector is realized on the voltage vector of main converter output, to realize the equivalent increase of the switching frequency of main converter, thus can effectively reduce the harmonic content of system current.The application is based on the motor structure of open-winding, by the voltage vector distribution of different power, different switching frequency main converter and harmonic compensation converter, realizes only increasing a small-power high-frequency converter, the effect of equivalent increase of the switching frequency of main converter is realized.Effectively reduce system current harmonic, optimize torque fluctuation and increase system efficiency.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of high-speed permanent magnet synchronous motor drive control, and particularly relates to a low-harmonic drive topology structure and control method of open-winding high-speed motor. BACKGROUND

[0002] High-speed permanent magnet synchronous motor has broad prospects and application value in the fields of military industry, aerospace, industry and civil use due to its advantages of high power density and high efficiency. However, high-speed permanent magnet synchronous motor often has the characteristics of small inductance and high fundamental frequency, and high-power high-speed permanent magnet synchronous motor further limits the switching frequency of power switching devices, which will cause the carrier ratio of the control system to decrease and the current harmonic content to increase. As a result, a series of problems such as system efficiency reduction, motor temperature rise increase and torque ripple increase are caused. Therefore, current harmonic suppression is a key problem affecting the application of high-speed permanent magnet synchronous motor.

[0003] The current harmonic suppression methods of high-speed permanent magnet synchronous motor system mainly include the following: increasing passive filter, adopting multi-level drive control system, and using high-frequency power devices of new materials such as SiC, etc. The method of increasing passive filter is simple and reliable, and can effectively filter out the time harmonics introduced by low carrier ratio. However, the volume and weight of the system increase, and in order to control the stability of the system under the condition of low carrier ratio, the cutoff frequency of the filter is not easy to be selected too low, so this method is more effective for high-frequency harmonics. The multi-level drive control system is a relatively mature scheme at present, which reduces the output voltage harmonics by increasing the number of output levels, thereby reducing the current harmonics, and has the advantage of reducing the voltage stress of power devices in high-voltage application occasions. However, the number of power devices increases in proportion to the number of added levels, which requires the volume of devices and drivers to increase by several times. High-frequency power devices such as SiC and high-performance control processors are applied in new energy vehicles and all-electric aircraft fields, and the system carrier ratio is increased by increasing the frequency of the control system, thereby fundamentally suppressing the increase of current harmonics. However, this scheme is expensive, and high-frequency power devices are prone to overvoltage and bridge arm crosstalk in application, and there is no high-power product at present. Based on the above, the existing schemes have their own advantages and disadvantages in system power density, price and performance, and need to be analyzed according to the application scene. SUMMARY

[0004] The purpose of the application is to overcome the disadvantages of the prior art, and to provide a low-harmonic drive topology structure and control method of open-winding high-speed motor, so as to solve the problem of large motor system current harmonics caused by low carrier ratio and other conditions, and to realize the purposes of optimizing torque ripple, reducing motor temperature rise and improving system efficiency by reducing current harmonics.

[0005] In order to achieve the above purpose, the following technical scheme is adopted in the application:

[0006] The open-winding high-speed motor low-harmonic drive topology structure comprises a main converter, a high-speed permanent magnet synchronous motor and a harmonic compensation converter;

[0007] The main converter is composed of three-phase first half-bridge circuits, two bridge arm power switching devices are arranged on each first half-bridge circuit, a DC power supply is connected to one side of the main converter, and the midpoint between the two bridge arm power switching devices on each first half-bridge circuit is connected to one end of one phase of the high-speed permanent magnet synchronous motor.

[0008] The harmonic compensation converter is composed of three-phase second half-bridge circuits, two bridge arm power switching devices are arranged on each second half-bridge circuit, a capacitor group is connected to one side of the harmonic compensation converter, and the midpoint between the two bridge arm power switching devices on each second half-bridge circuit is connected to the other end of one phase of the high-speed permanent magnet synchronous motor.

[0009] The further improvement of the application is that:

[0010] Preferably, the frequency of the bridge arm power switching device in the main converter is lower than the frequency of the bridge arm power switching device in the harmonic compensation converter.

[0011] Preferably, the bridge arm power switching device is an IGBT or a MOSFET.

[0012] Preferably, a current sensor is arranged on each phase connected between the high-speed permanent magnet synchronous motor and the main converter, and a voltage acquisition device is connected in parallel to the main converter and the harmonic compensation converter respectively.

[0013] The control method of the open-winding high-speed motor low-harmonic drive topology structure comprises the following steps: when the rotating speed of the high-speed motor approaches the rated rotating speed, the three-phase current input to the high-speed motor by the main converter is subjected to coordinate transformation to obtain the dq-axis current i d and i q ; the difference between the reference rotating speed ω eref of the high-speed motor and the actual rotating speed ω e is obtained, the q-axis current reference value i qref is obtained through a rotating speed controller, the difference between the dq-axis current reference value i dref and the dq-axis current i d is obtained, the difference between the q-axis current reference value i qref and the dq-axis current i q is obtained, the two differences are subjected to current controller calculation to obtain the dq-axis output voltage u sd and u sq ; the difference between the αβ-axis output voltage u sd and the αβ-axis output voltage u sq is obtained through coordinate transformation, and the αβ-axis output voltage u sα and the αβ-axis output voltage u sβ;

[0014] Output voltage u in the αβ axis system sα and u sβ Voltage vector synthesis is performed to obtain the output voltage vector. The amplitude and phase are determined based on the output voltage vector. Phase value, used to determine the output voltage vector Sector n section The main converter outputs a unit voltage vector by adjusting the switching on and off of the bridge arm power switching devices.

[0015] Unit voltage vector at the output of the main converter The transformation is performed to obtain the corresponding αβ axis unit voltage vector u. mα and u mβ ; Vector the output voltage With unit voltage vector After subtracting and inverting, the compensation voltage vector that the harmonic compensation converter should output is obtained. Will The input is fed into SVPWM to obtain the switching signal S of the harmonic compensation converter. f1-6 ;

[0016] When the high-speed motor is running at medium or low speed, all the upper bridge arm power switching devices in the harmonic compensation converter are turned on and all the lower bridge arm power switching devices are turned off; or all the upper bridge arm power switching devices are turned off and all the lower bridge arm power switching devices are turned on.

[0017] Preferably, when the speed of the high-speed motor is less than or equal to the rated speed, the output voltage u of the dq axis is... sd and u sq The switching signal S output to the main converter is obtained through SVPWM conversion. m1-6 .

[0018] Preferably, the motor stator voltage vector The expression is:

[0019]

[0020] in, The output voltage vector of the main converter. This is the output voltage vector of the harmonic compensation converter.

[0021] Preferably, the output voltage vector and The expression is:

[0022]

[0023] Wherein, u Am , u Bm and u Cm are three-phase output voltages of the main converter respectively, u Xn , u Yn and u Zn are three-phase output voltages of the harmonic compensation converter respectively.

[0024] Preferably, the three-phase output voltages of the main converter are:

[0025]

[0026] Wherein, m is the neutral point of the DC power supply, S A , S B and S C are conduction state functions of three-phase half-bridge circuits in the main converter respectively.

[0027] The three-phase output voltages of the harmonic compensation converter are:

[0028]

[0029] Wherein, S X , S Y and S Z are conduction state functions of three-phase half-bridge circuits in the harmonic compensation converter respectively.

[0030] Preferably, according to the sector n to which the voltage vector section belongs, the corresponding unit voltage vector output by the main converter is specifically:

[0031] The unit voltage vector of the main converter has 8 values, which are, 000 zero vector under the state of 111 The angle span between the remaining 6 adjacent values is π / 3.

[0032] Compared with the prior art, the present application has the following beneficial effects:

[0033] The application discloses a kind of open-winding high-speed motor low harmonic drive topological structures, this topological structure is based on the structure of open-winding motor, by increasing small-power high switching frequency harmonic compensation converter, high-frequency small voltage vector is superimposed on the voltage vector of main converter output, so as to realize the switching frequency of equivalent increase main converter, whereby the harmonic content of system current can be effectively reduced.The application is innovative, based on the motor structure of open-winding, by voltage vector distribution of main converter and harmonic compensation converter of different power, different switching frequency, it realizes that only a small-power high-frequency converter is added, and the effect of equivalent increase of main converter switching frequency is realized.It can effectively reduce system current harmonics, optimize torque ripple and increase system efficiency.In addition, the application is very flexible in control, the harmonic compensation converter can be switched in and out according to the working condition, and the switching frequency of the main converter can also be greatly reduced under unified control.The scheme has advantages in cost and performance, and is suitable for high-power high-speed motor application occasions.Overall, the current harmonic suppression scheme based on the open-winding structure is flexible in control, and only a small-power SiC three-phase bridge needs to be added to realize equivalent high-frequency voltage output.The scheme has unique advantages in medium and high-power application occasions.

[0034] Further, the current harmonics of high-speed motor system are mainly caused by low system carrier ratio, i.e., time harmonics introduced by the converter, and future motor drive control systems need to develop in the direction of integration and flexible control, therefore, the application designs a harmonic suppression scheme from the perspective of unified optimization of motor structure and converter topology, and introduces an open-winding structure.The open-winding permanent magnet synchronous motor does not need to change the original electromagnetic design and mechanical structure, and only needs to open and lead out the neutral point at one end of the winding.If the double converter is regarded as a main converter and a harmonic compensation converter, the main converter can output the main active power, the harmonic compensation converter can provide high-frequency reactive components, and the output frequency can be equivalent to be increased.In addition, the harmonic compensation converter only needs to provide a small amount of voltage components, and therefore, the power of the harmonic compensation converter can be smaller than that of the main converter.Meanwhile, when the speed is low and the current harmonic content is not high, the harmonic compensation converter can stop working to reduce system loss and simplify control.

[0035] The application also discloses a control method of the open-winding high-speed motor low harmonic drive topological structure, in which the harmonic compensation converter can be switched in and out according to the working condition, and the switching frequency of the main converter can also be greatly reduced under unified control.The scheme has advantages in cost and performance, and is suitable for high-power high-speed motor application occasions. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 It is an open-winding high-speed permanent magnet synchronous motor low harmonic converter topological structure schematic diagram.

[0037] Figure 2The schematic diagram of voltage vector distribution strategy for dual-converter unified operation mode.

[0038] Figure 3 The control block diagram for dual-converter unified operation mode.

[0039] Figure 4 The control block diagram for main converter single operation mode.

[0040] Figure 5 The three-phase current waveform for main converter single operation mode.

[0041] The main converter switching frequency is 10 kHz.

[0042] Figure 6 The three-phase current waveform for dual-converter unified operation mode.

[0043] The main converter switching frequency is equal to the motor fundamental frequency at this time: 600 Hz, and the sampling calculation frequency and switching frequency of the harmonic compensation converter are both 40 kHz.

[0044] Figure 7 The A-phase voltage waveform for dual-converter unified operation mode.

[0045] 1-direct current power supply; 2-main converter; 3-high-speed permanent magnet synchronous motor; 4-harmonic compensation converter; 5-capacitor; 6-current sensor; 7-voltage sensor. DETAILED DESCRIPTION

[0046] The application will be further described below in conjunction with the accompanying drawings:

[0047] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application; the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance; in addition, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting" should be understood broadly, for example, it can be fixed connection, or detachable connection; it can be direct connection, or indirect connection through intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0048] The system of the present application comprises a direct current power supply 1, a main converter 2, a high-speed permanent magnet synchronous motor 3, a harmonic compensation converter 4, a capacitor group 5, a current sensor 6 and a voltage sensor 7. Referring to Figure 1 , the three-phase winding of the open-winding high-speed permanent magnet synchronous motor 3 is connected to the output terminals, one end of which is connected to the ABC three-phase winding and the other end of which is connected to the XYZ three-phase winding. The main converter 2 is composed of three-phase first half-bridge circuits, and the midpoints of each phase bridge arm are connected to the ABC three-phase winding of the high-speed permanent magnet synchronous motor 3 in sequence. One end of the power device of the upper bridge arm of the main converter 2 is connected to the positive electrode of the direct current power supply 1, and one end of the power device of the lower bridge arm of the main converter 2 is connected to the negative electrode of the direct current power supply 1. The capacitor 5 is connected in parallel with the main converter 2 between the main converter 2 and the direct current power supply 1. The harmonic compensation converter 4 is composed of three-phase second half-bridge circuits connected in parallel, and the XYZ winding of the high-speed permanent magnet synchronous motor 3 is connected to the midpoints of the three-phase bridge arms of the harmonic compensation converter 4. The harmonic compensation converter 4 is connected in parallel with the capacitor group 5. In the above system, the three-phase current signals i a , i b and i c required for control are obtained by the current sensor 6, and the bus voltage signal is obtained by the voltage acquisition device 7, which is a voltage sensor or a sampling circuit. Thus, the topology structure of the present application is constructed.

[0049] More specifically, each phase of the permanent magnet synchronous motor 3 is composed of a resistor R, an inductor L and an alternating current signal source e connected in sequence; the main converter 2 is composed of three-phase first half-bridge circuits connected in parallel, and two bridge arm power devices, i.e. an upper bridge arm power device and a lower bridge arm power device, are arranged on each first half-bridge circuit. One end of the three upper bridge arm power devices is connected to the positive electrode of the direct current power supply 1, and one end of the three lower bridge arm power devices is connected to the negative electrode of the direct current power supply 1. An output line is arranged on the connection line of the upper bridge arm power device and the lower bridge arm power device, and the other end of each output line is connected to the resistor R of the permanent magnet synchronous motor. A current sensor 6 is arranged on each output line. The harmonic compensation converter 4 is composed of three-phase second half-bridge circuits connected in parallel, and two bridge arm power devices, i.e. an upper bridge arm power device and a lower bridge arm power device, are arranged on each second half-bridge circuit. An output line is arranged on the upper bridge arm power device and the lower bridge arm power device of each phase, and the other end of the output line is connected to an alternating current signal source e in the permanent magnet synchronous motor. The three-phase second half-bridge circuits in the harmonic compensation converter 4 are connected in parallel with the voltage acquisition device 7.

[0050] The switching frequency of the main converter 2 is lower than that of the harmonic compensation converter 4. In addition, the harmonic compensation converter 4 is usually switched into the system when the carrier is low, and is operated together with the main converter 2. In this application scenario, the output power of the harmonic compensation converter 3 is usually lower than that of the main converter 2, and therefore, the power devices constituting the harmonic compensation converter 3 can be selected to be lower than the power devices constituting the main converter 2 at the beginning of the design.

[0051] The control scheme of the low-harmonic topology includes two modes: a main converter 2 single-operation mode and a dual-converter unified-operation mode.

[0052] When the high-speed motor 3 is operated at a medium or low speed (≤80% rated speed), the carrier of the system is high, and the current harmonic content is low. Therefore, in this working condition, the control scheme can adopt the main converter 2 single-operation mode at a constant switching frequency, that is, the traditional motor drive mode. At this time, the upper end switch tube of each phase arm of the harmonic compensation converter 4 is all turned on, and the lower end switch tube is all turned off, or the upper end switch tube is all turned off, and the lower end switch tube is all turned on, so that the XYZ end of the high-speed permanent magnet synchronous motor is in the Y connection state.

[0053] Referring to Figure 4 the main converter 2 single-operation mode constant switching control diagram,

[0054] When the high-speed motor 3 is operated at a high speed, that is, close to the rated speed (>80% rated speed), the control system is switched to the dual-converter unified-operation mode, and the main converter 2 and the harmonic compensation converter 4 are switched according to the control mode. At this time, the main converter 2 and the harmonic compensation converter 4 jointly output the required voltage vector, wherein the main converter 2 only outputs a unit voltage vector, and at this time, the main converter 2 operates in a variable switching frequency mode, and the switching frequency is the same as the motor fundamental frequency, and each power device in the main converter 2 only needs to be turned on and turned off once in a motor fundamental frequency period. The main converter 2 operates in a square wave mode, and the switching frequency is the same as the motor fundamental frequency, that is, according to the vector rotation direction, the main converter 2 sequentially outputs and The harmonic compensation converter generates a PWM output with a fixed switching frequency according to the vector difference (shown in the figure) through SVPWM modulation. Figure 3

[0055] Figure 2 The voltage vector distribution strategy diagram in the dual-converter unified-operation mode. It is assumed that the A axis in the abc coordinate system coincides with the α axis in the αβ axis system, and the angle is 0. Correspondingly and correspond to 0, π / 3, 2π / 3, π, 4π / 3 and 5π / 3, respectively, and the six sectors I, II, III, IV, V and VI can be divided according to the dashed lines shown in the figure. If the calculated output voltage vector ​As shown in the figure, according to the voltage vector allocation rule, at this time... If it is in sector II, then the main converter 2 outputs a unit voltage vector. Based on the output voltage vector and unit voltage vector The difference is used to obtain the compensation voltage vector output by the harmonic compensation converter.

[0056] The three-phase output voltage of main converter 2 is:

[0057]

[0058] Where m is the neutral point of DC power supply 1, S A S B and S C These are the conduction state functions of the three-phase bridge arms, respectively. The three-phase output voltage of harmonic compensation converter 4 is:

[0059]

[0060] In the αβ axis system, assume the output voltage vector of main converter 2 is... The output voltage vector of harmonic compensation converter 4 is Then the output voltage vector and It can be represented as:

[0061]

[0062] The stator voltage vector of the motor can be obtained from (1)-(3). The expression:

[0063]

[0064] Among them, u mn for Figure 1 The voltage difference between the midpoints of the two sets of capacitors is shown. Therefore, the output voltage vector of this drive control system can be expressed as the difference between the voltage vectors of the main converter 2 and the harmonic compensation converter 4.

[0065] See Figure 4 The control logic diagram is shown in the stand-alone operation mode of main converter 2. When the control system is in the stand-alone operation mode of main converter 2, the specific control process includes the following steps:

[0066] Turn on the power devices of the three-phase upper arm of the harmonic compensation converter 4 and turn off the power devices of the three-phase lower arm. Connect XYZ to a single point.

[0067] Collection i a i b and ic Three-phase currents, after coordinate transformation, get currents in dq-axis system i d and i q , where the required rotor position signal θ e is obtained by position sensor or positionless algorithm. The control strategy adopts field-oriented control, the reference speed ω eref is compared with the actual speed ω e , and after the difference, the q-axis current reference value i qref is obtained through the speed controller. The dq-axis current reference value i dref and i qref are compared with the dq-axis current feedback value i d and i q , and after the difference, the dq-axis output voltage u sd and u sq are obtained through the current controller. After coordinate transformation, the output voltage in αβ-axis system u sα and u sβ is obtained, and then through SVPWM transformation, the switching signal S m1-6 output to the main converter 2 is obtained.

[0068] Referring to Figure 3 the control logic diagram in the dual-converter unified operation mode, when the control system is in the dual-converter unified operation mode, the specific control process includes the following steps:

[0069] Three-phase currents i a , i b and i c are collected, and after coordinate transformation, currents in dq-axis system i d and i q are obtained, where the required rotor position signal θ e is obtained by position sensor or positionless algorithm. The control strategy adopts field-oriented control, the reference speed ω eref is compared with the actual speed ω e , and after the difference, the q-axis current reference value i qref is obtained through the speed controller. The dq-axis current reference value i dref and i qref are compared with the dq-axis current feedback value i d and i q , and after the difference, the dq-axis output voltage u sd and u sq are obtained through the current controller. After coordinate transformation, the output voltage in αβ-axis system u sα and u sβ is obtained. This part is the same as the main converter 2 single operation mode.

[0070] The output voltage in αβ-axis system u sα and u sβThe voltage vectors are synthesized to obtain an output voltage vector The amplitude and phase are The phase is arctan(u sβ / u sα ). According to the phase value of the voltage vector , it is determined which sector n section the voltage vector belongs to, and the main converter 2 outputs different unit voltage vectors The bridge arm state combination S of the main converter 2 is composed of 3-bit binary numbers, and there are 8 values. In addition to the zero vectors in the states of 000 and 111 and , there are 6 unit voltage vectors with an amplitude of , which are and in turn counterclockwise from the α axis. Their angle span is π / 3. If the α axis is defined as 0, the angle increases counterclockwise to 2π, and when the output voltage vector is in the interval [π / 6, π / 2), the main converter 2 outputs the unit vector and so on.

[0071] Through the transformation of the unit voltage vector output by the main converter 2, the corresponding αβ-axis unit voltage vectors u mα and u mβ are obtained. After the difference between the calculated output voltage vector and the unit voltage vector output by the main converter 2 is taken, the compensation voltage vector that the harmonic compensation converter should output is obtained The αβ-axis system , i.e., u fα and u fβ , is input to the SVPWM to obtain the switching signal S f1-6 of the harmonic compensation converter 4.

[0072] Embodiment

[0073] The above control strategy is tested, and the parameters of the open-winding permanent magnet synchronous motor used are shown in Table 1.

[0074] Table 1: Main parameters of open-winding high-speed permanent magnet synchronous motor

[0075]

[0076]

[0077] Figure 3The control block diagram of the dual-converter unified operation mode. In this embodiment, the fundamental frequency of the motor is 600Hz, i.e. the switching frequency of the main converter 2 is 600Hz. The sampling calculation frequency and the switching frequency of the harmonic compensation converter 4 are both 40kHz.

[0078] Figure 4 The control block diagram of the main converter single operation mode. In this embodiment, the switching signal S f1-6 of the harmonic compensation converter is [101010], i.e. the upper tube of the three-phase bridge arm is turned on and the lower tube is turned off. The sampling calculation frequency and the switching frequency of the main converter are both 10kHz.

[0079] Figure 5 and Figure 6 are the three-phase current waveforms of the main converter single operation mode and the dual-converter unified operation mode at the rated speed of the motor, respectively. Figure 5 The sampling calculation and the switching frequency of the main converter 2 are both 10kHz, and the fundamental frequency of the motor is 600Hz, i.e. the carrier ratio is 16.67. It can be found that the current harmonic content is large at this time. When switched to the dual-converter unified operation mode, the switching frequency of the main converter 2 is reduced to 600Hz, and the heat generation and the loss of the main converter 2 are greatly reduced. The sampling calculation and the switching frequency of the harmonic compensation converter 4 are both 40kHz. From Figure 6 It can be found that the three-phase current harmonic content is very small at this time, and the system efficiency is greatly improved.

[0080] Figure 7 is the A-phase voltage waveform of the dual-converter unified operation mode, which specifically includes the A-phase output voltage u Am of the main converter 2, the A-phase output voltage u Xn of the harmonic compensation converter 4 and the A-phase winding voltage u AX of the motor. It can be found from the figure that at the rated speed, the main converter 2 outputs the main voltage vector in the form of a square wave, and the harmonic compensation converter 4 only needs to compensate for part of the voltage vector. Therefore, the output power of the harmonic compensation converter 4 is usually less than half of that of the main converter 2, which means that the withstand voltage value of the power device in the harmonic compensation converter 4 can be smaller, thereby reducing the volume, weight and price thereof.

[0081] The application discloses a kind of high-speed permanent magnet synchronous motor low harmonic drive topology structure and control method.This scheme is based on open-winding motor structure, motor one end is connected corresponding motor power three-phase main converter, three-phase main converter is powered by external power supply and provides main active power for motor.Another end of motor is connected with small-power high-frequency three-phase harmonic compensation converter, which realizes energy storage and output through capacitor group, mainly provides a small amount of active and reactive compensation for motor.In control strategy, the application provides two control modes.When motor operates at medium-low speed, current harmonic content is low, main converter is operated in single mode, harmonic compensation converter upper tube or lower tube is turned on, the other end is turned off, so that motor Y is connected, and main converter is operated in constant switching frequency field-oriented control.When motor operates at high speed, current harmonic content is high, and the driving control system is switched to dual-converter unified operation mode.At this time, main converter outputs square wave with carrier ratio of 1 according to real-time voltage vector sector, and harmonic compensation converter outputs compensation voltage vector, which compensates the square wave voltage output by main converter, so that equivalent high-frequency voltage vector is obtained at both ends of motor three-phase winding.The application is based on open-winding motor structure, and by combining dual-converter with different switching frequencies and different output powers, voltage vector with better sine degree is outputted, so that three-phase current harmonic is effectively reduced.The scheme described in the application only needs to open motor three-phase winding nodes and increase a small-power high-frequency three-phase half-bridge, so that current harmonic can be effectively suppressed, and the cost and volume weight are superior to multi-level topology.In addition, the scheme described in the application is flexible in control, can not affect the original system operation mode, can also reduce the switching frequency of main converter, and improve the overall life of driving system.In conclusion, the application is a reasonable scheme that can effectively suppress motor current harmonic under low carrier ratio condition, and has obvious advantages in high-power high-speed motor application occasions.

[0082] The above only describes preferred embodiments of the application and is not intended to limit the application, and any modification, equivalent replacement, improvement, etc., made within the spirit and principle of the application should be included in the protection scope of the application.

Claims

1. A control method of an open-winding high-speed motor low-harmonic drive topology, characterized by, Based on the low harmonic drive topology of the open-winding high-speed motor, comprising a main converter (2), a high-speed permanent magnet synchronous motor (3) and a harmonic compensation converter (4); The main converter (2) is composed of three-phase first half-bridge circuits, and two bridge arm power switching devices are arranged on each first half-bridge circuit; A DC power supply (1) is connected to one side of the main converter (2), and the midpoint between the two bridge arm power switching devices on each first half-bridge circuit is connected to one end of one phase of the high-speed permanent magnet synchronous motor (3); A capacitor bank is arranged in parallel with the main converter (2) between the main converter (2) and the DC power supply (1); The harmonic compensation converter (4) is composed of three-phase second half-bridge circuits, and two bridge arm power switching devices are arranged on each second half-bridge circuit; A capacitor bank (5) is connected to one side of the harmonic compensation converter (4), and the midpoint between the two bridge arm power switching devices on each second half-bridge circuit is connected to the other end of one phase of the high-speed permanent magnet synchronous motor (3); When the rotation speed of the high-speed motor (3) approaches the rated rotation speed, the three-phase current inputted to the high-speed motor (3) by the main converter, after being coordinate-transformed, obtains the current in the dq axis system i d and i q , the approach rated rotation speed being the rotation speed of the high-speed motor (3) >80% of the rated rotation speed; the reference rotation speed of the high-speed motor (3) ω eref and the actual rotation speed ω e , the difference between which obtains a difference value, the difference value obtaining the q-axis current reference value through a rotation speed controller i qref ; the d-axis current reference value i dref and the current in the d-axis system i d , the difference between which obtains the q-axis current reference value i qref and the current in the q-axis system i q , the difference between which obtains the dq-axis output voltage through a current controller u sd and u sq ; u sd and u sq , the coordinate transformation of which obtains the output voltage in the αβ axis system u sα and u sβ ; Output voltage under αβ axis system u sα And u sβ Carrying out voltage vector synthesis to obtain an output voltage vector The amplitude and phase of the output voltage vector According to the phase value of the output voltage vector Determine the sector to which the output voltage vector n section The main transformer (2) outputs the corresponding unit voltage vector By adjusting the on-off of the bridge arm power switching device The unit voltage vector output by the main converter (2) The unit voltage vector output by the main converter (2) is transformed to obtain a corresponding αβ-axis unit voltage vector u mα And u mβ The output voltage vector is subtracted from the unit voltage vector and inverted to obtain a compensation voltage vector that the harmonic compensation converter (4) should output Theis input to the SVPWM to obtain a switching signal of the harmonic compensation converter (4) S f1-6 ; When the high-speed motor (3) operates at medium and low speed, the upper bridge arm power switching devices of the harmonic compensation converter (4) are all turned on, and the lower bridge arm power switching devices are all turned off; or the upper bridge arm power switching devices are all turned off, and the lower bridge arm power switching devices are all turned on, and the high-speed motor (3) operates at medium and low speed, that is, the rotational speed of the high-speed motor (3) is less than or equal to 80% of the rated rotational speed.

2. The control method of open-winding high-speed motor low-harmonic drive topology of claim 1, wherein, When the rotation speed of the high-speed motor (3) is ≤ 80% of the rated rotation speed, the dq-axis output voltage u sd and u sq The switching signals output to the main converter (2) are obtained by SVPWM conversion S m1-6 .

3. The control method of open-winding high-speed motor low-harmonic drive topology of claim 1, wherein, The output voltage vector The expression is: (4) wherein, is a unit voltage vector output by the main converter (2), is an output voltage vector of the harmonic compensation converter (4), u mn is a voltage difference between the two sets of capacitors, one of which is a set of capacitors provided in parallel with the main converter (2) between the main converter (2) and the DC power source (1), and the other of which is a set of capacitors (5) connected by the harmonic compensation converter (4).

4. The control method of open-winding high-speed motor low-harmonic drive topology of claim 3, wherein, Output voltage vector And The expression for: wherein u Am , u Bm and u Cm are the three-phase output voltages of the main converter (2), u Xn , u Yn and u Zn are the three-phase output voltages of the harmonic compensation converter (4).

5. The control method of open-winding high-speed motor low-harmonic drive topology of claim 4, wherein, The three-phase output voltage of the main converter (2) is: wherein S A , S B and S C are the conduction state functions of the three-phase half-bridge circuits in the primary converter (2), respectively. The three-phase output voltage of the harmonic compensation converter (4) is: wherein S X , S Y and S Z are the conduction state functions of the three-phase half-bridge circuit in the harmonic compensating converter (4), respectively.

6. The control method of open-winding high-speed motor low-harmonic drive topology of claim 1, wherein, According to the voltage vector The sector to which the voltage vector belongs n section The main transformer (2) outputs a corresponding unit voltage vector, specifically: The unit voltage vector of the main converter (2) has 8 values, respectively, 000 zero vector , 111 state , the angle span between the remaining 6 adjacent values is π / 3.

Images