CN103199790A - Control system and control method for three-phase four-bridge-arm permanent magnet synchronous motor - Google Patents

Abstract

A three-phase four-arm permanent magnet synchronous motor control system and control method. The traditional three-phase three-arm main circuit topology will be difficult to maintain the safe and reliable operation of the system when there is a phase loss or a single-phase open circuit fault, which limits its use in aviation, navigation, explosion-proof, etc. There are strict requirements on the redundancy and reliability of the control system occasions. The composition of the present invention includes : a main circuit, the 220V single-phase AC input ( 1 ) of the main circuit is connected with a single-phase rectification circuit ( 2 ), and the single-phase rectification circuit is connected with a four-leg inverter ( 3 ) connection, the four-leg inverter is connected to the permanent magnet synchronous motor ( 8 ) through bridge arm A ( 4 ), bridge arm B ( 5 ), bridge arm C ( 6 ), bridge arm D ( 7 ), and The aforementioned bridge arm A , bridge arm B , and bridge arm C are connected to the current sampling circuit ( 10 ), and the aforementioned permanent magnet synchronous motor is connected to the photoelectric code disc ( 11 ). The invention is used for the control of a three-phase four-arm permanent magnet synchronous motor .

Description

Three-phase four-arm permanent magnet synchronous motor control system and control method

Technical field:

The invention relates to a control system and a control method of a three-phase four-arm permanent magnet synchronous motor.

Background technique:

The traditional three-phase three-arm main circuit topology adopts the voltage space vector modulation (SVPWM) technology, which can also reduce the harmonic content of the winding current and improve the utilization rate of the DC bus voltage, thereby reducing the torque ripple of the motor and broadening the motor's capacity. speed range. However, this traditional topology will be difficult to maintain the safe and reliable operation of the system when there is a phase loss or a single-phase open circuit fault. Where required, its application field is greatly limited.

Invention content:

The purpose of the present invention is to provide a three-phase four-arm permanent magnet synchronous motor control system and control method.

Above-mentioned purpose realizes by following technical scheme:

A kind of three-phase four bridge arm permanent magnet synchronous motor control system, its composition comprises: main circuit, the 220V single-phase AC input of described main circuit is connected with single-phase rectification circuit, and described single-phase rectification circuit is connected with four bridge arms The inverter is connected, and the four-arm inverter is connected to the permanent magnet synchronous motor through the bridge arm A, the bridge arm B, the bridge arm C, and the bridge arm D, and the bridge arm A, the bridge arm B, and the bridge arm C is connected with the current sampling circuit, the permanent magnet synchronous motor and the photoelectric code disc.

In the three-phase four-arm permanent magnet synchronous motor control system, the photoelectric encoder is connected to the QEP unit of the control circuit, the QEP unit is connected to the PI controller D, and the current sampling circuit is connected to the A/ D module is connected, and described A/D module, described QEP unit are respectively connected with PI controller A, PI controller B, PI controller C through coordinate transformation, and described PI controller D is connected with speed controller , the speed controller is connected to the PI controller A, the PI controller A, PI controller B, and PI controller C are connected to the current controller, and the current controller is connected to the 3D- The SVPWM control is connected, the 3D-SVPWM control is connected with the photoelectric isolation driving circuit, and the photoelectric isolation driving circuit is connected with the four-leg inverter.

In the three-phase four-arm permanent magnet synchronous motor control system, the digital display tube is connected to the SPI unit, the host computer is connected to the SCI unit, the keyboard is connected to the I/O unit B, and the fault detection unit is connected to the I/O unit A.

A control method for a three-phase four-arm permanent magnet synchronous motor control system:

(1) Working method of permanent magnet synchronous motor:

为三相定子绕组通电流合成矢量、

为永磁体磁链，

为

与轴的夹角，

为轴与

相轴的夹角。 In the formula

The current synthesis vector for the three-phase stator winding,

is the permanent magnet flux linkage,

for

and the included angle of the axis,

for axis with

The included angle of the phase axis.

坐标系的变换（Clarke变换）为 ABC coordinate system to

The transformation of the coordinate system (Clarke transformation) is

                   (1)

(1)

The corresponding inverse transformation (Clarke ^-1 transformation) is

                   (2)

(2)

坐标系到

坐标系的变换（Park变换）为

coordinate system to

The transformation of the coordinate system (Park transformation) is

                    (3)

(3)

The corresponding inverse transformation (Park ^-1 transformation) is

                    (4)

(4)

In the formula, q _r is the electrical angle.

The system uses a convex-mounted permanent magnet synchronous motor, which can be considered to be equal to the equivalent inductance of the AC and DC axes, that is, L _q = L _d . So the voltage equation of PMSM is

                    (5)

(5)

In the formula, i _X , u _X , e _X are the phase current, the voltage of the midpoint of the relative DC side, and the phase induced electromotive force ( X can be one of A, B, and C ); u _N is the neutral point of the motor to the first The voltage at the midpoint of the four bridge arms; r is the stator resistance, L and M are the self-inductance and mutual inductance of the stator winding. The neutral current i _N is

                         (6)

(6)

Using coordinate transformation, the voltage equation (5) of PMSM is transformed into dq 0 coordinate system, we have

              (7)

(7)

                       (8)

(8)

                (9)

(9)

Electromagnetic torque is

                         (10)

(10)

The equation of motion is

                      (11)

(11)

In formulas (7) to (11), L _dq is the equivalent inductance of the d and q axes; ω _r is the electrical angular velocity; y _PM is the flux linkage of the permanent magnet of the rotor; L ₀ is the zero-axis inductance; J is the moment of inertia ; _n is the pole logarithm.

(2) The working method of four-leg inverter control:

Since the vector control scheme with i _d = 0 is selected, the specific implementation process is as follows: First, detect the motor rotor position and stator winding current; use the rotor position to calculate the motor speed, and output the reference value i _q ^of the current torque component through the speed controller , at the same time given the current excitation component i _d ^* =0; and the coordinate transformation of the stator winding current to obtain the feedback components i _q and i _d , and output the reference voltage space vector d, q- axis components u _d ^* and u _q through the current controller ^* ;Finally, 6 channels of PWM output signals are generated by the SVPWM module, and the power of the three-phase three-leg inverter is amplified to drive the permanent magnet synchronous motor, and finally realize the double closed-loop control of the speed and current.

与

之间的关系为 The three-phase four-leg inverter adds a bridge arm connected to the neutral point of the motor on the basis of the three-phase three-leg inverter, thus adding a controllable neutral current , and the zero-axis current can be obtained from equations (1) and (6)

and

The relationship between

                             (12)

(12)

就可以对中线电流进行间接控制。 Therefore, as long as the zero axis current is controlled

neutral current Take indirect control.

From formula (2), (4) we can know

        (13)

(13)

为零，这样只需要控制零轴电流

为零即可，即 Under normal operating conditions, the neutral current

is zero, so only the zero axis current needs to be controlled

can be zero, that is,

                         (14)

(14)

             (15)

(15)

             (16)

(16)

=0。由于永磁同步电机的电磁转矩取决于i _d 、i _q 的大小，此时，为保证与正常运行时有着相同的驱动特性，必须产生与故障前一致的i _d 、i _q ，这里需要

作补偿，因此不再等于0。 When a phase-opening fault occurs in a certain phase, here it is assumed that an open-circuit fault occurs in phase A (the situation is the same when there are open-circuit faults in phase B and C ), at this time there is

=0. Since the electromagnetic torque of the permanent magnet synchronous motor depends on the size of i _d and i _q , at this time, in order to ensure the same driving characteristics as in normal operation, it is necessary to generate i _d and i _q that are consistent with those before the fault. Here,

To compensate, it is no longer equal to 0.

=0代入式（13），可以得到 Bundle

=0 into formula (13), we can get

                           (17)

(17)

(18)

             (19)

(19)

Through equations (7) and (17) we get

          (20)

(20)

According to formula (17) or (20), two configurations can be used to achieve the purpose of torque compensation, that is, adopt zero-axis current compensation closed-loop control mode to meet the requirements of formula (17); or adopt formula (20), adopt zero _The shaft voltage open-loop control mode realizes the output of zero shaft voltage u0 . In this way, the purpose of fault tolerance can be achieved, and there is no need to modify any hardware circuits.

This patent adopts the zero-axis current compensation closed-loop control method, since it adopts i _d =0 control, it can be obtained by simplifying the formula (17)

                          (21)

(twenty one)

Therefore, in the fault state, it is only necessary to compensate the zero-axis current according to formula (21).

i _q sinq _r。然后经过PI控制器获得u _d ^*、u _q ^*、u ₀ ^*，再经过Park^-1变换、Clarke^-1变换、3D-SVPWM的调制、功率放大驱动四桥臂逆变器的8个功率开关管，最终构成三相四桥臂永磁同步电动机速度、电流双闭环控制系统。 The working method of the above-mentioned three-phase four-leg permanent magnet synchronous motor control system, the given speed and the feedback speed are obtained through the speed controller to obtain the given value i _q ^* of the current torque component, and the sampled phase currents i _A , i _B , i After Clarke and Park transformation, _C obtains i _d , i _q , i ₀ in the dq0 rotating coordinate system, ^and compares them with current given i _q ^* , i _d * , i ₀ ^* , where i _d ^* , i 0 _* ^give The fixed values are all 0, and in the case of single-phase fault i ₀ ^* need to add compensation value

i _q sin q _r . Then get u _d ^* , u _q ^* , u ₀ ^* through PI controller, and then through Park ^-1 transformation, Clarke ^-1 transformation, 3D-SVPWM modulation, power amplification to drive 8 power switches of the four-leg inverter Tube, and finally constitute a three-phase four-arm permanent magnet synchronous motor speed, current double closed-loop control system.

Beneficial effect:

1. The three-phase four bridge arm permanent magnet synchronous motor control system proposed by the present invention adds a bridge arm connected to the neutral point of the motor on the basis of traditional three-phase three bridge arms, and adopts three-dimensional voltage space vector modulation (3D- SVPWM) technology makes it drive permanent magnet synchronous motor with good operating characteristics. At the same time, this topology connects the fourth bridge arm to the neutral point of the motor, providing a path for the neutral current, which can better balance the output and suppress interference, and in the case of phase loss or single-phase fault, through the Appropriate adjustment of the control strategy to maintain the normal operating characteristics of the motor.

The invention has over-voltage, under-voltage and over-temperature protection functions to ensure safe and reliable operation of the system.

The present invention applies the id=0 control mode, that is, the maximum torque-to-current ratio control (MTPA). The method obtains the required motor output torque with the minimum stator current, thereby improving the system efficiency.

Description of drawings:

Accompanying drawing 1 is the overall block diagram of the system of the present invention. In the figure, 1 is 220V single-phase AC input, 2 is single-phase rectifier circuit, 3 is four-leg inverter, 4 is bridge arm A, 5 is bridge arm B, 6 is bridge arm C, and 7 is bridge arm D , 8 is the permanent magnet synchronous motor, 10 is the current sampling circuit, 11 is the photoelectric encoder, 12 is the QEP unit, 20 is the PI controller D, 14 is the A/D module, 15 is the coordinate transformation, 17 is the PI controller A , 18 is PI controller B, 19 is PI controller C, 21 is speed controller, 16 is current controller, 13 is 3D-SVPWM control, 9 is photoelectric isolation drive circuit, 22 is digital display tube, 23 is SPI 24 is the host computer, 25 is the SCI unit, 26 is the keyboard, 27 is the I/O unit B, 28 is the fault detection unit, and 29 is the I/O unit A.

Fig. 2 is a system control structure diagram of the present invention.

Fig. 3 is a schematic diagram of the position signal differential receiving circuit of the present invention.

Fig. 4 is a schematic diagram of the current sampling circuit of the present invention.

Fig. 5 is a schematic diagram of the main circuit of the present invention.

Fig. 6 is a schematic diagram of the isolated driving circuit of the present invention.

Fig. 7 is a reference diagram of the reference coordinate system of the present invention.

Fig. 8 is a schematic diagram of vector control of permanent magnet synchronous motor id = ₀ according to the present invention.

Fig. 9 is a schematic structural diagram of the three-phase four-leg inverter of the present invention.

Fig. 10 is a vector diagram of 3D-SVPWM in the ABC coordinate system of the present invention.

Fig. 11 is a diagram of the correspondence between pointer variable N and tetrahedron in the present invention.

Fig. 12 is a schematic diagram of switch sorting when N=1 of the present invention.

Fig. 13 is a flow chart of the main program of the system of the present invention.

Fig. 14 is a flow chart of the rotor initial positioning program of the present invention.

Fig. 15 is a flow chart of the rotor position detection program of the present invention.

Fig. 16 is a flow chart of the timer interrupt subroutine of the present invention.

Fig. 17 is the 3D-SVPWM program flowchart of the present invention.

Fig. 18 is the response curve of rotational speed and torque when the present invention is given rotational speed and load changes.

Fig. 19 is a three-phase winding current response curve at a given speed and load variation of the present invention.

Fig. 20 is the speed and torque response curve of the present invention (single-phase fault occurs at 0.05s).

Fig. 21 is the three-phase stator current and neutral line current response curves of the present invention (single-phase fault occurs at 0.05s).

Fig. 22 is the dq0 axis current response curve of the present invention (single-phase fault occurs at 0.05s).

Detailed ways:

Example 1:

A three-phase four-arm permanent magnet synchronous motor control system with fault-tolerant function, its composition includes: a main circuit, the 220V single-phase AC input 1 of the main circuit is connected with a single-phase rectifier circuit 2, and the single-phase The rectifier circuit is connected with the four-arm inverter 3, and the four-arm inverter is connected with the permanent magnet synchronous motor 8 through the bridge arm A4, the bridge arm B5, the bridge arm C6, and the bridge arm D7. A, bridge arm B, and bridge arm C are connected to the current sampling circuit 10 , the permanent magnet synchronous motor and the photoelectric code disc 11 .

Example 2:

The three-phase four-arm permanent magnet synchronous motor control system with fault-tolerant function described in embodiment 1, the described photoelectric code disc is connected with the QEP unit 12 of the control circuit, and the described QEP unit is connected with the PI controller D20, and the Described current sampling circuit is connected with A/D module 14, and described A/D module, described QEP unit are respectively connected with PI controller A17, PI controller B18, PI controller C19 through coordinate transformation 15, described The PI controller D is connected with the speed controller 21, the speed controller is connected with the PI controller A, and the PI controller A, PI controller B, and PI controller C are jointly connected with the current controller 16, the current controller is connected to the 3D-SVPWM control 13, the 3D-SVPWM control is connected to the photoelectric isolation drive circuit 9, and the photoelectric isolation drive circuit is connected to the four-leg inverter .

Example 3:

In the three-phase four-arm permanent magnet synchronous motor control system with fault tolerance described in Embodiment 1 or 2, the digital display tube 22 is connected to the SPI unit 23, the host computer 24 is connected to the SCI unit 25, and the keyboard 26 is connected to the I/O unit B27 is connected, and the fault detection unit 28 is connected with the I/O unit A29.

Example 4:

A control method for a three-phase four-arm permanent magnet synchronous motor:

(1) Working method of permanent magnet synchronous motor:

为三相定子绕组通电流合成矢量、为永磁体磁链，

为

与

轴的夹角，

为

轴与

相轴的夹角。 In the formula

The current synthesis vector for the three-phase stator winding, is the permanent magnet flux linkage,

for

and

the included angle of the axis,

for

axis with

The included angle of the phase axis.

坐标系的变换（Clarke变换）为 ABC coordinate system to

The transformation of the coordinate system (Clarke transformation) is

                   (1)

(1)

The corresponding inverse transformation (Clarke ^-1 transformation) is

(2)

坐标系到

坐标系的变换（Park变换）为

coordinate system to

The transformation of the coordinate system (Park transformation) is

                    (3)

(3)

The corresponding inverse transformation (Park ^-1 transformation) is

                    (4)

(4)

In the formula, q _r is the electrical angle.

The system uses a convex-mounted permanent magnet synchronous motor, which can be considered to be equal to the equivalent inductance of the AC and DC axes, that is, L _q = L _d . So the voltage equation of PMSM is

                    (5)

(5)

In the formula, i _X , u _X , e _X are the phase current, the voltage of the midpoint of the relative DC side, and the phase induced electromotive force ( X can be one of A, B, and C ); u _N is the neutral point of the motor to the first The voltage at the middle point of the four bridge arms; r is the stator resistance, L and M are the self-inductance and mutual inductance of the stator winding. The neutral current i _N is

                         (6)

(6)

Using coordinate transformation, the voltage equation (5) of PMSM is transformed into dq 0 coordinate system, we have

              (7)

(7)

                       (8)

(8)

                (9)

(9)

Electromagnetic torque is

                         (10)

(10)

The equation of motion is

(11)

In formulas (7) to (11), L _dq is the equivalent inductance of the d and q axes; ω _r is the electrical angular velocity; y _PM is the flux linkage of the permanent magnet of the rotor; L ₀ is the zero-axis inductance; J is the moment of inertia ; _n is the pole logarithm.

(2) The working method of four-leg inverter control:

Since the vector control scheme with i _d = 0 is selected, the specific implementation process is as follows: First, detect the motor rotor position and stator winding current; use the rotor position to calculate the motor speed, and output the reference value i _q ^of the current torque component through the speed controller , at the same time given the current excitation component i _d ^* =0; and the coordinate transformation of the stator winding current to obtain the feedback components i _q and i _d , and output the reference voltage space vector d, q- axis components u _d ^* and u _q through the current controller ^* ;Finally, 6 channels of PWM output signals are generated by the SVPWM module, and the power of the three-phase three-leg inverter is amplified to drive the permanent magnet synchronous motor, and finally realize the double closed-loop control of the speed and current.

，而由式（1）、（6）可以得到零轴电流

与

之间的关系为 The three-phase four-leg inverter adds a bridge arm connected to the neutral point of the motor on the basis of the three-phase three-leg inverter, thus adding a controllable neutral current

, and the zero-axis current can be obtained from equations (1) and (6)

and

The relationship between

                             (12)

(12)

进行间接控制。 Therefore, as long as the zero axis current is controlled neutral current

Take indirect control.

From formula (2), (4) we can know

        (13)

(13)

为零，这样只需要控制零轴电流

为零即可，即 Under normal operating conditions, the neutral current

is zero, so only the zero axis current needs to be controlled

can be zero, that is,

                         (14)

(14)

             (15)

(15)

             (16)

(16)

=0。由于永磁同步电机的电磁转矩取决于i _d 、i _q 的大小，此时，为保证与正常运行时有着相同的驱动特性，必须产生与故障前一致的i _d 、i _q ，这里需要作补偿，因此不再等于0。 When a phase-opening fault occurs in a certain phase, here it is assumed that an open-circuit fault occurs in phase A (the situation is the same when there are open-circuit faults in phase B and C ), at this time there is

=0. Since the electromagnetic torque of the permanent magnet synchronous motor depends on the size of i _d and i _q , at this time, in order to ensure the same driving characteristics as in normal operation, it is necessary to generate i _d and i _q that are consistent with those before the fault. Here, To compensate, it is no longer equal to 0.

=0代入式（13），可以得到 Bundle

=0 into formula (13), we can get

                           (17)

(17)

(18)

             (19)

(19)

Through equations (7) and (17) we get

(20)

According to formula (17) or (20), two configurations can be used to achieve the purpose of torque compensation, that is, adopt zero-axis current compensation closed-loop control mode to meet the requirements of formula (17); or adopt formula (20), adopt zero _The shaft voltage open-loop control mode realizes the output of zero shaft voltage u0 . In this way, the purpose of fault tolerance can be achieved, and there is no need to modify any hardware circuits.

This patent adopts the zero-axis current compensation closed-loop control method, and since it adopts i _d =0 control, the formula (17) can be simplified to get

                          (21)

(twenty one)

Therefore, in the fault state, it is only necessary to compensate the zero-axis current according to formula (21).

Example 5:

In the above three-phase four-leg permanent magnet synchronous motor control method, the given speed and feedback speed are obtained through the speed controller to obtain the given value i _q ^* of the current torque component, and the sampled phase currents i _A , i _B , and i _C pass through Clarke and Park transform, get i _d , i _q , i ₀ in the dq0 rotating coordinate system, and compare with the current given i _q ^* , i _d ^* , i ₀ ^* , where the given values of i _d ^* , i ₀ ^* are all 0, and in the case of single-phase fault i ₀ ^* need to add compensation value i _q sin q _r . Then get u _d ^* , u _q ^* , u ₀ ^* through PI controller, and then through Park ^-1 transformation, Clarke ^-1 transformation, 3D-SVPWM modulation, power amplification to drive 8 power switches of the four-leg inverter Tube, and finally constitute a three-phase four-arm permanent magnet synchronous motor speed, current double closed-loop control system.

Embodiment 6:

In the three-phase four-arm permanent magnet synchronous motor control system described in embodiment 1 or 2 or 3, the rotor detection sensor of the permanent magnet synchronous motor in Figure 3 not only detects the rotor position, but also measures the motor speed. This system uses a hybrid encoder. In order to eliminate common mode interference and improve anti-interference ability, the motor position detection signal is transmitted in a differential mode, and then the differential chip DS3486 is used to receive the differential signal, and input to the corresponding pin of the DSP after shaping. .

Figure 4 The phase current frequency of the permanent magnet synchronous motor is from zero to hundreds of Hz. Here, the current Hall module CHB-25NP is used to realize the detection of the stator phase current. Taking the A-phase current sampling as an example, the secondary side current of the Hall sensor is controlled by the resistor R12 Sampling to get U _R12 , after bias, low-pass filtering and clamping processing, it is input to the A/D conversion port of DSP for processing.

Figure 5 is the AC-DC-AC conversion circuit, the input is single-phase 220V, after rectification and voltage stabilization, DC power of about 310V is obtained. The rectifier bridge uses KBPC3510, its reverse peak voltage is 1000V, and the normal working current can reach 35A; C2 is used to filter out high-order harmonics in the DC voltage; C3 plays the role of voltage stabilization and providing a freewheeling circuit for the motor winding.

The drive circuit in Figure 6 uses IR2110 as the drive chip. The IR2110 upper bridge arm drive power supply is designed for bootstrap suspension drive, which reduces the number of power supplies used by the drive circuit. The input side of IR2110 uses optocoupler 6N137 to realize the electrical isolation of the control signal and the main circuit. The PWM control signal is isolated by the optocoupler, reversed by the inverter 74LS06 and pulled up to 20V to match the input voltage of the IR2110. In order to increase the reliability of turning off the power device, a negative 5V turn-off voltage is provided for the driving signal through the regulator tubes ZD2, ZD3 and capacitors C11 and C12.

The core control unit adopts TI company's DSP processing chip TMS320F2812, the highest frequency can reach 150MHz, the chip peripherals include 16 channels of 12-bit precision ADC, 2 channels of SCI, and two event management modules (EVA and EVB). Each event management module includes 6-way PWM/CMP, 2-way QEP and 3-way CAP.

Embodiment 7:

For the three-phase four-leg permanent magnet synchronous motor control system described in Embodiment 1 or 2 or 3 or 4 or 5, Fig. 9 is a schematic structural diagram of a three-phase four-leg inverter, and the phase midpoint voltage of the inverter is U _AN , U _BN , U _CN . In order to make the expression of the switching voltage vector clear and concise, firstly, the values of U _AN , U _BN , and U _CN are standardized (let U _dc =1), and the voltage space vector is represented by the per unit value.

Assume that S _A , S _B , S _C , and S _N represent the switching states of the four bridge arms A, B, C, and N respectively. The upper tube of each bridge arm is turned on (the lower tube is turned off) is 1, and the upper tube is turned off. (lower tube conduction) is 0, so there are 16 switch states in total; each switch state corresponds to a synthesized switch vector, here let U ₀ to U ₁₅ be the 16 switch vectors, where U ₀ and U ₁₅ are The zero vector, and its corresponding relationship is shown in Table 1.

Table 1 Three-phase four-leg inverter switch state table

Drawing these 16 synthetic switching voltage vectors into a space vector diagram in the static coordinate system ( ABC coordinate system) will result in a space dodecahedron, as shown in Figure 10. Take state 13 as an example, at this time SA , S _{B ,} S _C , _SN are 1, 0, 1, 1 respectively; U _AN , U _BN , U _CN are 0, -1, 0 respectively; this means The upper tubes of the A, C, and N bridge arms are turned on, and the lower tubes are turned off; the upper tubes of the B bridge arms are turned off, and the lower tubes are turned on. The switching voltage vector is U ₁₃ , which is located at (0,-1,0) coordinates in the stationary coordinate system.

=0、

=0、

=0和

-

=0、

-

=0、

-

=0将控制区域分割成24个小的空间四面体，并且每一个四面体由三个非零开关电压矢量和两个零开关电压矢量构成，这样只要确定了参考电压矢量所在空间四面体就可以利用对应的开关电压矢量来进行拟合。例如，某一时刻的参考电压矢量在ABC坐标系中的坐标为(

,

,

)，并且有

>0、

>0、

>0、

-

>0、

->0、

-

>0，则能判断出它所在的小空间四面体，从而确定合成它的三个非零开关电压矢量为、

、

。 For the switch vector diagram 10, we can use the plane

=0,

=0,

=0 and

-

=0,

-

=0,

-

=0 divides the control area into 24 small space tetrahedrons, and each tetrahedron is composed of three non-zero switching voltage vectors and two zero switching voltage vectors, so as long as the space tetrahedron where the reference voltage vector is located can be determined The fitting is performed using the corresponding switching voltage vectors. For example, the coordinates of the reference voltage vector at a certain moment in the ABC coordinate system are (

,

,

), and have

>0,

>0,

>0,

-

>0,

- >0,

-

>0, the small space tetrahedron it is located in can be judged, and the three non-zero switching voltage vectors that synthesize it can be determined as ,

,

.

In order to simplify this judgment, we define six variables k ₁ to k ₆ , which represent the division directions of the six planes, as long as they are determined to be 0 or 1, the position of the reference voltage vector can be judged. The expressions of the six variables are as follows

                          (22)

(twenty two)

                           (23)

(twenty three)

                           (24)

(twenty four)

(25)

                     (26)

(26)

                     (27)

(27)

、

、为标准化参考电压矢量。 In the formula,

,

, is the normalized reference voltage vector.

Define a pointer function:

                     (28)

(28)

到

这六个变量的符号和唯一的指针变量N联系起来，通过计算N共有24个值，正好与24个四面体一一对应。图11给出了指针变量N所对应的四面体位置以及三个非零开关电压矢量。 Will

arrive

The symbols of these six variables are connected with the only pointer variable N , and there are 24 values in total through calculation, which correspond exactly to 24 tetrahedrons one by one. Figure 11 shows the position of the tetrahedron corresponding to the pointer variable N and three non-zero switching voltage vectors.

After judging the position of the tetrahedron where the reference voltage vector is located and determining the three non-zero switching voltage vectors used to synthesize it, the corresponding value of each non-zero switching voltage vector and zero vector can be calculated by the principle of equal volt-second area. duty cycle. Since the reference voltage vector needs to be synthesized equivalently with three non-zero switch voltage vectors and two zero vectors, the size of the reference voltage vector is equal to the sum of the products of each switch voltage vector corresponding to the current moment and its duty cycle, as shown in the formula (29). In order to obtain the value of the duty ratio, formula (29) is transformed to obtain formula (30) and (31).

(31)

In the formula, U _ref is the reference voltage vector; d ₁ , d ₂ , d ₃ are the duty cycles corresponding to the three non-zero switching voltage vectors; U _{dx_A} , U _{dx_B} , U _{dx_C} are the switching voltage vectors in the ABC coordinate system The projection value below (x=1, 2, 3); d ₀ is the duty cycle of the zero vector (this zero vector can be any one of the two zero vectors U ₀ and U ₁₅ , or both combination). Taking N = 1 as an example, the non-zero switching voltage vectors are U ₈ , U ₉ , U ₁₁ , and their duty ratios are calculated according to formula (30):

                (32)

(32)

Tidy up

                    (33)

(33)

Using the same method, you can get the corresponding situation when N is equal to the other 23 values. As shown in Table 2, the corresponding relationship between the pointer variable N and the non-zero switching voltage vector and its duty cycle is given.

Table 2 Correspondence between pointer variable N and vector group and duty cycle

After the duty cycle of each switch voltage vector is obtained, their turn-on time can be obtained by multiplying it by the cycle time. In the following, it is only necessary to arrange the turn-on sequence of each switch voltage vector to arrange the switch sequence reasonably. In order to reduce the harmonic content of the output voltage, the number of switching operations and its loss, this paper adopts the centrosymmetric sorting method of inserting two zero vectors. Taking the pointer variable N= 1 as an example, U ₈ , U ₉ , and U ₁₁ are the corresponding non-zero switching voltage vectors at this time, and the sorting method is shown in Figure 12.

_Finally , according to this centrosymmetric sorting method, _the calculation formula of the switching point is given as shown in formula ( _{34 )} . tube conduction time.

Figures 13 to 17 are the flow charts of the system software.

Embodiment 8:

The three-phase four-leg permanent magnet synchronous motor control system described in embodiment 1 or 2 or 3 or 4 or 5, in order to verify the response capability of the system to the given speed and load changes, the motor speed is given by 500r at 0.03s /min changes to 1000r/min; at 0.06s, the motor load increases from 5N·m to 8N·m. The speed, torque and three-phase current responses are shown in Figures 18 and 19. It can be seen from the figure that the given speed changes from 500r/min to 1000r/min at 0.03s, and the rotor speed follows the given value very well. At the same time, the winding current amplitude remains unchanged, the frequency is accelerated, and the acceleration time is 4ms; At 0.06s, the motor load changes from 5 N·m to 8 N·m, and the output torque of the motor increases instantaneously, reaching a balance, the winding current amplitude increases, and the frequency remains unchanged. It takes 1ms, but the speed is affected. very small.

In order to verify the feasibility of fault tolerance and simulate a single-phase fault state, it is set that the A-phase bridge arm is disconnected at t=0.05s and at the same time, the given value of i ₀ ^* is switched to fault compensation in the zero-axis current given module Value, as shown in Figure 20-22, other things remain unchanged, the load torque is still 5N·m, and the given speed is still 500r/min.

Fig. 20 is a speed and torque response curve diagram for this case. It can be seen that there is almost no change in the speed and torque after 0.05s.

倍，相位差从2p/3变成了p/3。幅值的调整使得转矩不变，相位的改变避免了转矩脉动的产生。 Figure 21 shows the changes of the three-phase stator current and the neutral current before and after the fault. It can be seen that i _B and i _C after 0.05s are about the same as before the fault

times, the phase difference changes from 2p/3 to p/3. The adjustment of the amplitude keeps the torque unchanged, and the change of the phase avoids the generation of torque ripple.

Figure 22 shows the variation of dq 0-axis current, and the magnitudes of i _d and i _q remain unchanged, thus ensuring the consistency of the electromagnetic torque before and after the fault; i ₀ is the compensation current of the 0-axis before and after the fault.

Claims (5)

1. a three-phase four bridge arm permanent magnet synchronous motor control system, its composition comprises: main circuit, it is characterized in that: the 220V single-phase AC input of described main circuit is connected with single-phase rectifier circuit, and described single-phase The rectifier circuit is connected with the four-arm inverter, and the four-arm inverter is connected with the permanent magnet synchronous motor through the bridge arm A, the bridge arm B, the bridge arm C, and the bridge arm D, and the bridge arm A, Bridge arm B and bridge arm C are connected to the current sampling circuit, and the permanent magnet synchronous motor is connected to the photoelectric code disc. 2. three-phase four bridge arm permanent magnet synchronous motor control system according to claim 1, is characterized in that: described photoelectric code disk is connected with the QEP unit of control circuit, and described QEP unit is connected with PI controller D , the current sampling circuit is connected with the A/D module, the A/D module and the QEP unit are respectively connected with the PI controller A, the PI controller B, and the PI controller C through coordinate transformation, and the described The PI controller D is connected to the speed controller, the speed controller is connected to the PI controller A, and the PI controller A, PI controller B, and PI controller C are jointly connected to the current controller , the current controller is connected to the 3D-SVPWM control, the 3D-SVPWM control is connected to the photoelectric isolation driving circuit, and the photoelectric isolation driving circuit is connected to the four-leg inverter. 3. according to claim 1 and 2 described three-phase four bridge arm permanent magnet synchronous motor control system, it is characterized in that: digital display tube is connected with SPI unit, upper computer is connected with SCI unit, and keyboard is connected with I/O unit B , the fault detection unit is connected to I/O unit A. 4. A three-phase four-arm permanent magnet synchronous motor control method is characterized in that: (1) Working method of permanent magnet synchronous motor: In the formula

The current synthesis vector for the three-phase stator winding,

is the permanent magnet flux linkage,

for

and

the included angle of the axis,

for axis with

The angle between the phase axes; ABC coordinate system to

The transformation of the coordinate system (Clarke transformation) is

(1) The corresponding inverse transformation (Clarke ^-1 transformation) is

(2) coordinate system to

The transformation of the coordinate system (Park transformation) is

(3) The corresponding inverse transformation (Park ^-1 transformation) is

(4) In the formula, q _r is the electrical angle; The system adopts a convex-mounted permanent magnet synchronous motor, and the equivalent inductance of the AC and D axis can be considered to be equal, that is, L _q = L _d , so the voltage equation of PMSM is

(5) In the formula, i _X , u _X , e _X are the phase current, the voltage of the midpoint of the relative DC side, and the phase induced electromotive force ( X can be one of A, B, and C ); u _N is the neutral point of the motor to the first The voltage at the middle point of the four bridge arms; r is the stator resistance, L and M are the self-inductance and mutual inductance of the stator winding, and the neutral current i _N is

(6) Using coordinate transformation, the voltage equation (5) of PMSM is transformed into dq 0 coordinate system, we have

(7)

(8)

(9) Electromagnetic torque is

(10) The equation of motion is (11) In formulas (7) to (11), L _dq is the equivalent inductance of the d and q axes; ω _r is the electrical angular velocity; y _PM is the flux linkage of the permanent magnet of the rotor; L ₀ is the zero-axis inductance; J is the moment of inertia ; _n is the pole logarithm; (2) The working method of four-leg inverter control: Since the vector control scheme with i _d = 0 is selected, the specific implementation process is as follows: First, detect the motor rotor position and stator winding current; use the rotor position to calculate the motor speed, and output the reference value i _q ^of the current torque component through the speed controller , at the same time given the current excitation component i _d ^* =0; and the coordinate transformation of the stator winding current to obtain the feedback components i _q and i _d , and output the reference voltage space vector d, q- axis components u _d ^* and u _q through the current controller ^* ;Finally, the SVPWM module generates 6 channels of PWM output signals, which are amplified by the three-phase three-leg inverter to drive the permanent magnet synchronous motor, and finally realize the double closed-loop control of speed and current; The three-phase four-leg inverter adds a bridge arm connected to the neutral point of the motor on the basis of the three-phase three-leg inverter, thus adding a controllable neutral current , and the zero-axis current can be obtained from equations (1) and (6)

and The relationship between

(12) Therefore, as long as the zero axis current is controlled

neutral current exercise indirect control; From formula (2), (4) we can know

(13) Under normal operating conditions, the neutral current is zero, so only the zero axis current needs to be controlled

can be zero, that is,

(14)

(15)

(16) When a phase-opening fault occurs in a certain phase, here it is assumed that an open-circuit fault occurs in phase A (the situation is the same when there are open-circuit faults in phase B and C ), at this time there is

=0, since the electromagnetic torque of the permanent magnet synchronous motor depends on the size of i _d and i _q , at this time, in order to ensure the same driving characteristics as in normal operation, i _d and i _q must be consistent with those before the fault, need here to compensate, so it is no longer equal to 0; Bundle

=0 into formula (13), we can get

(17)

(18) (19) Through equations (7) and (17) we get

(20) According to formula (17) or (20), two configurations can be used to achieve the purpose of torque compensation, that is, adopt zero-axis current compensation closed-loop control mode to meet the requirements of formula (17); or adopt formula (20), adopt zero The shaft voltage open-loop control mode realizes the output of zero shaft voltage u ₀ , so that the purpose of fault tolerance can be achieved without modifying any hardware circuit; This patent adopts the zero-axis current compensation closed-loop control method, and since it adopts i _d =0 control, the formula (17) can be simplified to get

(twenty one) Therefore, in the fault state, it is only necessary to compensate the zero-axis current according to formula (21). 5. The working method of the above-mentioned three-phase four-arm permanent magnet synchronous motor control system is characterized in that: the given rotational speed and the feedback rotational speed obtain the given value i _q ^* of the current torque component through the speed controller, and the sampled phase current i _A , i _B , and i _C undergo Clarke and Park transformations to obtain i _d , i _q , i ₀ in the dq0 rotating coordinate system, and compare them with the current given i _q * , i _d ^* , i ₀ ^{* ,} where i _d ^* , the given value of i ₀ ^* is 0, and in the case of single-phase fault, i ₀ ^* needs to add compensation value

i _q sin q _r , then get u _d ^* , u _q ^* , u ₀ ^* through PI controller, and then through Park ^-1 transformation, Clarke ^-1 transformation, 3D-SVPWM modulation, power amplification to drive four-bridge arm inverter The 8 power switch tubes of the device finally constitute the speed and current double closed-loop control system of the three-phase four-arm permanent magnet synchronous motor.

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