Three-phase motor power control method and device

Abstract

The embodiment of the invention provides a three-phase motor power control method and device, and the method comprises the steps: substituting a three-phase motor parameter into a preset motor power prediction model, and constructing a motor power prediction model for a current three-phase motor; respectively acquiring a positive sequence electric signal component and a negative sequence electric signal component of each phase of the current three-phase motor, and an on-off state of a power converter for supplying power to the three-phase motor, and predicting a predicted power component of the three-phase motor in the next voltage period through the motor power prediction model; and according to the predicted power component, determining voltage vector action time for the next voltage period of the power converter. According to the invention, the power of each phase of the three-phase motor is controlled by adjusting the on-off state of the power converter, so that the stability of the power among the phases is maintained, and the operation stability and control performance of the motor speed regulation system are improved under the condition that the three-phase power grid is unbalanced.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of electric energy conversion, and particularly relates to a three-phase motor power control method and device. BACKGROUND

[0002] In a double-fed motor speed regulation system, the speed regulation of fan and pump devices needs to be realized by means of two-stage electric energy conversion circuit to realize electric energy conversion and motor speed regulation. However, when the three-phase power grid voltage is unbalanced, the input current of the electric energy conversion circuit at the input power grid side will be distorted, and the direct current output by the electric energy conversion circuit at the input power grid side will cause output voltage fluctuation. The direct current input by the power conversion circuit at the double-fed motor side will fluctuate, thereby causing the three-phase voltage output by the power conversion circuit at the double-fed motor side to be distorted, resulting in unbalanced voltage and power of each phase of the double-fed motor, affecting the normal operation of the motor, weakening the performance of the motor, and causing a series of chain negative effects such as speed regulation accuracy reduction and energy conversion efficiency reduction.

[0003] Therefore, it is urgent to provide a control strategy for the double-fed motor side circuit under the condition of three-phase power grid voltage imbalance, so as to improve the stability and control performance of the double-fed motor speed regulation system and reduce the interference of harmonics on the power system. SUMMARY

[0004] The present disclosure provides a three-phase motor power control method and device to improve the stability and control performance of the motor speed regulation system under the condition of three-phase power grid imbalance.

[0005] Based on the above problems, in a first aspect, the present disclosure provides a three-phase motor power control method, comprising: substituting the three-phase motor parameters into a preset motor power prediction model to construct a motor power prediction model for the current three-phase motor; wherein the preset motor power prediction model is used to establish a numerical correlation between the electrical signal component at the rotor side of the three-phase motor and the power component of the three-phase motor; respectively acquiring the positive sequence electrical signal component and the negative sequence electrical signal component of each phase of the current three-phase motor, and the switching state of the power converter for supplying power to the three-phase motor, and predicting the predicted power component of the three-phase motor in the next voltage period through the motor power prediction model; determining the voltage vector action time of the next voltage period of the power converter according to the predicted power component.

[0006] In combination with the first aspect, in a possible implementation manner, the preset motor power prediction model is: ; wherein, R is an equivalent resistance value at the rotor side of the three-phase motor; is an equivalent inductance value of a rotor side of a three-phase motor; is an angular frequency of a three-phase alternating voltage of a rotor side of a three-phase motor; , , , , and are power components of a rotor side of a three-phase motor, respectively; , , , , and are derivatives of the power components of the rotor side of the three-phase motor, respectively; , , and are electrical signal components of a rotor side of a three-phase motor, respectively; and are control quantities of a power converter.

[0007] With reference to the first aspect, in a possible implementation, the respective acquisition of the positive sequence electrical signal component and the negative sequence electrical signal component of each phase of the current three-phase motor, and the switching state of the power converter supplying power to the three-phase motor, the prediction of the predicted power component of the three-phase motor in the next voltage period by the motor power prediction model, comprises: the acquired positive sequence electrical signal component and the negative sequence electrical signal component of each phase of the current three-phase motor, and the current switching state of the power converter, are input into the motor power prediction model to determine the current power component of the three-phase motor in the current voltage period; the power component of the three-phase motor in the next voltage period is predicted according to the current power component, and the power control quantity and the action time of the current switching state of the power converter.

[0008] With reference to the first aspect, in a possible implementation, the determination of the voltage vector action time of the power converter in the next voltage period according to the predicted power component comprises: a value function is constructed based on the error between the predicted power component of the three-phase motor in the next voltage period and the expected power component, and the action time of the power supply vector of the power converter is associated with the predicted power component and the value function; the value function is solved, and the first action time of the power supply vector of the power converter corresponding to the minimum value of the value function is determined as the voltage vector action time in the next voltage period.

[0009] In combination with the first aspect, in a possible implementation, the method further includes: generating a control signal to control a switching device of the power converter according to the determined voltage vector acting time of the next voltage period, adjusting a switching state of the power converter in the next voltage period, and controlling a power component of the three-phase motor in the next voltage period.

[0010] In combination with the first aspect, in a possible implementation, the switching state of the power converter includes: a first switching state in which an upper switching device of a first bridge arm of the power converter is open, a lower switching device of the first bridge arm is closed, an upper switching device of a second bridge arm is open, a lower switching device of the second bridge arm is closed, and an upper switching device of a third bridge arm is open, a lower switching device of the third bridge arm is closed; a second switching state in which the upper switching device of the first bridge arm of the power converter is open, the lower switching device of the first bridge arm is closed, the upper switching device of the second bridge arm is open, the lower switching device of the second bridge arm is closed, and the upper switching device of the third bridge arm is closed, the lower switching device of the third bridge arm is open; a third switching state in which the upper switching device of the first bridge arm of the power converter is open, the lower switching device of the first bridge arm is closed, the upper switching device of the second bridge arm is closed, the lower switching device of the second bridge arm is open, and the upper switching device of the third bridge arm is open, the lower switching device of the third bridge arm is closed; a fourth switching state in which the upper switching device of the first bridge arm of the power converter is open, the lower switching device of the first bridge arm is closed, the upper switching device of the second bridge arm is closed, the lower switching device of the second bridge arm is open, the upper switching device of the third bridge arm is closed, and the lower switching device of the third bridge arm is open; a fifth switching state in which the upper switching device of the first bridge arm of the power converter is closed, the lower switching device of the first bridge arm is open, the upper switching device of the second bridge arm is open, the lower switching device of the second bridge arm is closed, and the upper switching device of the third bridge arm is open, the lower switching device of the third bridge arm is closed; a sixth switching state in which the upper switching device of the first bridge arm of the power converter is closed, the lower switching device of the first bridge arm is open, the upper switching device of the second bridge arm is open, the lower switching device of the second bridge arm is closed, and the upper switching device of the third bridge arm is closed, the lower switching device of the third bridge arm is open; a seventh switching state in which the upper switching device of the first bridge arm of the power converter is closed, the lower switching device of the first bridge arm is open, the upper switching device of the second bridge arm is closed, the lower switching device of the second bridge arm is open, and the upper switching device of the third bridge arm is open, the lower switching device of the third bridge arm is closed; an eighth switching state in which the upper switching device of the first bridge arm of the power converter is closed, the lower switching device of the first bridge arm is open, the upper switching device of the second bridge arm is closed, the lower switching device of the second bridge arm is open, the upper switching device of the third bridge arm is closed, and the lower switching device of the third bridge arm is open.

[0011] In combination with the first aspect, in a possible implementation, the switching state is determined according to a sector in the voltage period; and the sector is determined according to a size relationship of each-phase voltage in the voltage period. In a case where the first phase voltage is greater than zero, the second phase voltage is less than zero, and the second phase voltage is greater than the third phase voltage, a first sector of the voltage cycle is determined, and the switching state of the power converter is determined to be one of the first switching state, the fifth switching state, the seventh switching state, and the eighth switching state; In a case where the first phase voltage is greater than the second phase voltage, the second phase voltage is greater than zero, and the third phase voltage is less than zero, a second sector of the voltage cycle is determined, and the switching state of the power converter is determined to be one of the first switching state, the fifth switching state, the seventh switching state, and the eighth switching state; In a case where the second phase voltage is greater than the first phase voltage, the first phase voltage is greater than zero, and the third phase voltage is less than zero, a third sector of the voltage cycle is determined, and the switching state of the power converter is determined to be one of the first switching state, the third switching state, the seventh switching state, and the eighth switching state; In a case where the second phase voltage is greater than zero, the first phase voltage is less than zero, and the third phase voltage is less than the first phase voltage, a fourth sector of the voltage cycle is determined, and the switching state of the power converter is determined to be one of the first switching state, the third switching state, the seventh switching state, and the eighth switching state; In a case where the second phase voltage is greater than zero, the third phase voltage is less than zero, and the first phase voltage is less than the third phase voltage, a fifth sector of the voltage cycle is determined, and the switching state of the power converter is determined to be one of the first switching state, the third switching state, the fourth switching state, and the eighth switching state; In a case where the second phase voltage is greater than the third phase voltage, the third phase voltage is greater than zero, and the first phase voltage is less than zero, a sixth sector of the voltage cycle is determined, and the switching state of the power converter is determined to be one of the first switching state, the third switching state, the fourth switching state, and the eighth switching state; In a case where the third phase voltage is greater than the second phase voltage, the second phase voltage is greater than zero, and the first phase voltage is less than zero, a seventh sector of the voltage cycle is determined, and the switching state of the power converter is determined to be one of the first switching state, the second switching state, the fourth switching state, and the eighth switching state; In a case where the third phase voltage is greater than zero, the first phase voltage is less than zero, and the first phase voltage is greater than the second phase voltage, an eighth sector of the voltage cycle is determined, and the switching state of the power converter is determined to be one of the first switching state, the second switching state, the fourth switching state, and the eighth switching state; In a case where the third phase voltage is greater than zero, the first phase voltage is less than zero, and the second phase voltage is less than the first phase voltage, a ninth sector of the voltage cycle is determined, and the switching state of the power converter is determined to be one of the first switching state, the second switching state, the sixth switching state, and the eighth switching state; In a case that the third phase voltage is greater than the first phase voltage, the first phase voltage is greater than zero, and the second phase voltage is less than zero, a tenth sector of the voltage period is determined, and the switching state of the power converter is determined as one of the first switching state, the second switching state, the sixth switching state, and the eighth switching state; In a case that the first phase voltage is greater than the third phase voltage, the third phase voltage is greater than zero, and the second phase voltage is less than zero, an eleventh sector of the voltage period is determined, and the switching state of the power converter is determined as one of the first switching state, the fifth switching state, the sixth switching state, and the eighth switching state. In a case that the first phase voltage is greater than zero, the third phase voltage is less than zero, and the second phase voltage is less than the third phase voltage, a twelfth sector of the voltage period is determined, and the switching state of the power converter is determined as one of the first switching state, the fifth switching state, the sixth switching state, and the eighth switching state.

[0012] With reference to the first aspect, in a possible implementation, the power control amount of the switching state is determined by a motor power prediction model according to the positive sequence and negative sequence voltage components of the voltage period and a switching state voltage control amount; wherein the switching state voltage control amount is determined according to the input voltage of the power converter and the switching state.

[0013] With reference to the first aspect, in a possible implementation, the three-phase motor parameters include an equivalent resistance value of the three-phase motor and an input inductance value of the three-phase motor.

[0014] The second aspect of the present disclosure provides a three-phase motor power control device, including: A model construction module is configured to substitute three-phase motor parameters into a preset motor power prediction model to construct a motor power prediction model for a current three-phase motor. A prediction module is configured to acquire positive sequence and negative sequence electrical signal components of each phase of the current three-phase motor and a switching state of a power converter for supplying power to the three-phase motor, and predict a predicted power component of the three-phase motor in a next voltage period by using the motor power prediction model. A determination module is configured to determine a voltage vector action time of the power converter in the next voltage period according to the predicted power component.

[0015] The beneficial effects of the embodiments of the present disclosure include: The embodiments of the present disclosure provide a three-phase motor power control method and device, comprising: substituting the three-phase motor parameters into a preset motor power prediction model to construct a motor power prediction model for the current three-phase motor; respectively obtaining the positive-sequence electrical signal component and the negative-sequence electrical signal component of each phase of the current three-phase motor, as well as the switching state of the power converter that supplies power to the three-phase motor, and predicting the predicted power component of the three-phase motor in the next voltage cycle through the motor power prediction model; and determining the voltage vector action time for the next voltage cycle of the power converter based on the predicted power component. In the present disclosure, the power of each phase of the three-phase motor is controlled by adjusting the switching state of the power converter to maintain the stability of the power between the phases, thereby improving the stability and control performance of the motor speed control system under the condition of unbalanced three-phase power grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic flow chart of a three-phase motor power control method provided in an embodiment of the present disclosure; Figure 2 A schematic diagram of the structure of a three-phase motor and a power supply circuit provided in an embodiment of the present disclosure; Figure 3 A schematic diagram of voltage cycle sector division provided in an embodiment of the present disclosure; Figure 4 Voltage and current simulation waveforms provided by the embodiment of the present disclosure; Figure 5 A DC voltage simulation waveform diagram provided by an embodiment of the present disclosure; Figure 6 Active power and reactive power simulation waveforms provided by the embodiment of the present disclosure; Figure 7 A power component simulation waveform diagram provided by an embodiment of the present disclosure; Figure 8 A schematic structural diagram of a three-phase motor power control device provided in an embodiment of the present disclosure. DETAILED DESCRIPTION

[0017] The present disclosure provides a three-phase motor power control method and apparatus. Preferred embodiments of the present disclosure are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are intended only to illustrate and explain the present disclosure and are not intended to limit the present disclosure. Furthermore, the embodiments and features of the embodiments may be combined with one another unless there is a conflict.

[0018] The present disclosure provides a three-phase motor power control method. Figure 1 As shown, it can be implemented as follows: S101, substituting the three-phase motor parameters into a preset motor power prediction model to construct a motor power prediction model for the current three-phase motor; S102, respectively acquiring positive sequence electrical signal components and negative sequence electrical signal components of each phase of the current three-phase motor, and a switching state of a power converter for supplying power to the three-phase motor, predicting a predicted power component of the three-phase motor in a next voltage period through the motor power prediction model; S103, determining a voltage vector action time for the power converter in the next voltage period according to the predicted power component.

[0019] In the embodiments of the present disclosure, the power supply circuit of the three-phase motor can be implemented as a circuit diagram as shown in Figure 2 The power supply circuit can include two-stage power conversion circuits. The power conversion circuit at the grid side can convert three-phase alternating current into direct current and output to the power conversion circuit (i.e., the power converter) at the three-phase motor side. The power converter can convert the direct current into three-phase alternating current and output to the three-phase motor to supply power to the three-phase motor. When the three-phase alternating current at the grid side fluctuates, resulting in unbalanced voltages of each phase, the direct current output by the power conversion circuit at the grid side will also fluctuate, thereby causing unstable voltages and power of each phase of the three-phase motor. The method provided by the present disclosure can control the power converter at the three-phase motor side, adjust the switching state of the power converter, control the power of each phase of the three-phase motor, and maintain the stability of the power among the phases.

[0020] In the present disclosure, the three-phase motor can be implemented as a double-fed motor as shown in Figure 2 The stator of the double-fed motor is connected to each phase line in the grid, and the rotor is connected to each bridge arm in the power converter. The power converter can include three bridge arms, each of which can include two upper and lower switching devices, a total of six switching devices (as shown in Figure 2 , , , , and The switching devices can be implemented as power switches such as insulated gate bipolar transistors (IGBT, Insulated Gate Bipolar Transistor) and metal oxide semiconductor field effect transistors (MOSFET, Metal-Oxide-Semiconductor Field-Effect Transistor). The three bridge arms are connected in parallel and connected in parallel with a filter capacitor The filter capacitor is connected between the input terminals of the power converter and the output terminals of the power conversion circuit at the grid side. The upper and lower switching devices of each bridge arm are respectively connected to one phase line in the rotor of the three-phase motor, serving as the output terminals of the power converter.

[0021] ​Each switch device can receive a control signal to change its own switching state, and through a corresponding control strategy and high-frequency switching of the on-off state of each switch device, the input DC power can be converted into AC power output to each phase line of the rotor of the three-phase motor 、 and . The control signal for each switch device can be a space vector pulse width modulation (SVPWM) signal, which can be a pulse waveform capable of switching the switching state of the switch device in a specific order.

[0022] The parameters of the three-phase motor can be determined based on the physical parameters of the three-phase motor itself, such as the equivalent resistance value on the rotor side of the three-phase motor, the equivalent inductance value on the rotor side of the three-phase motor, and the angular frequency of each phase line on the rotor side of the three-phase motor.

[0023] Based on the voltage values of each item in the AC power cycle of the three-phase motor obtained, the positive and negative sequence electrical signal component input motor power prediction model can be converted, and based on the switching state of the power converter in the current three-phase voltage cycle, the power component in the current cycle can be determined. Further, based on the power component in the current cycle and the switching state of the power converter in the current cycle, the predicted power component of the power converter in the next cycle can be predicted.

[0024] The predicted power component and the expected power component are compared to obtain a value function, and the control strategy for the switching state of the power converter in the next cycle is determined based on the value function, so as to maintain the stable operation of the three-phase motor.

[0025] In yet another embodiment provided by the present disclosure, the preset motor power prediction model is: ; wherein, is the equivalent resistance value on the rotor side of the three-phase motor; is the equivalent inductance value on the rotor side of the three-phase motor; is the angular frequency of the three-phase AC voltage on the rotor side of the three-phase motor; 、 、 、 、 and are power components on the rotor side of the three-phase motor, respectively; 、 、 、 、 and are derivatives of the power components on the rotor side of the three-phase motor, respectively; , , and are respectively the electrical signal components on the rotor side of the three-phase motor; and are respectively the control quantities of the power converter.

[0026] In the embodiments of the present disclosure, the preset motor power prediction model can be as shown in the following formula (1).

[0027] (1) In formula (1), is the equivalent resistance value on the rotor side of the three-phase motor, is the equivalent inductance value on the rotor side of the three-phase motor; is the angular frequency of the three-phase alternating voltage on the rotor side of the three-phase motor, is the frequency of the three-phase alternating voltage. After substituting these parameters into the above formula (1), the motor power prediction model for the current three-phase motor can be obtained.

[0028] Formula (1) can calculate six power components of the three-phase motor through input data, so as to predict the current operation of the three-phase motor. The six power components are respectively , , , , and . Among them, is the average value of the active power component on the rotor side of the three-phase motor, is the cosine quadratic component of the active power on the rotor side of the three-phase motor, is the sine quadratic component of the active power on the rotor side of the three-phase motor, is the average value of the reactive power component on the rotor side of the three-phase motor, is the cosine quadratic component of the reactive power on the rotor side of the three-phase motor, is the sine quadratic component of the reactive power on the rotor side of the three-phase motor. , , , , and are respectively the derivatives of the above power components.

[0029] In the above formula (1), and respectively represent the three-phase alternating voltage , and on the rotor side of the three-phase motor, the positive sequence components in the two-phase stationary coordinate system (αβ coordinate system); and respectively represent the three-phase AC voltage on the rotor side of the three-phase motor 、 and the negative sequence components in the two-phase stationary coordinate system (αβ coordinate system) ; 、 、 and are the square values of the positive and negative components of the corresponding voltage.

[0030] and are the control quantities of the power converter, wherein and are the switching components of the switches in the three-phase bridge arm of the power converter on the rotor side of the three-phase motor in the αβ coordinate system, which can be obtained by converting the on-off state of each bridge arm in the three-phase bridge arm. The on-off state of each bridge arm of the three-phase bridge arm 、 and may correspond to the state of the upper and lower switching devices in a bridge arm, respectively, which can be represented by 0 and 1. In the case where the upper switching device in a certain bridge arm is closed and the lower switching device is turned off, ; in the case where the lower switching device in a certain bridge arm is closed and the upper switching device is turned off, . By the different on-off states of each bridge arm, the switching state of the power converter can be finally composed.

[0031] In yet another embodiment provided by the present disclosure, the above step S102 "obtaining the positive and negative sequence electrical signal components of each phase of the three-phase motor and the switching state of the power converter for the three-phase motor, and predicting the predicted power component of the three-phase motor in the next voltage period through the motor power prediction model" can be implemented as follows: Step 1, obtaining the positive and negative sequence electrical signal components of each phase of the three-phase motor and the current switching state of the power converter, and determining the current power component of the three-phase motor in the current voltage period through the motor power prediction model; Step 2, predicting the power component of the three-phase motor rotor side in the next voltage period according to the current power component, the power control quantity and the action time of the current switching state of the power converter.

[0032] In the embodiment of the present disclosure, the voltage value of each phase line on the rotor side of the three-phase motor can be collected by a sampling device, and the voltage value of each phase line can be converted to the two-phase stationary coordinate system through the Clarke transformation, so as to obtain the positive and negative sequence electrical signal components in the αβ coordinate system.

[0033] Suppose the current voltage period is Period, the positive and negative sequence electrical signal components are substituted into the above formula (1), the power components in the current period can be obtained, respectively 、 、 、 、 and .

[0034] According to the obtained power components in the current voltage period, combined with the power control amount and the action time of the current switching state of the power converter, the predicted power components in the next period are obtained. Assuming that the next period is , the predicted power components of 、 、 、 、 and can be obtained by the following formula (2).

[0035] (2) In the above formula (2), 、 、 、 、 、 are the unit time power control amounts of different power converter switching states for different power components of the three-phase motor rotor side, 、 and are the action times of different switching states in the current period. According to the current switching state and the action time, the power components in the next voltage period can be predicted.

[0036] In another embodiment of the present disclosure, the above step S103 "determining the voltage vector action time for the next voltage period of the power converter according to the predicted power components" can be implemented as the following steps: Step one, based on the error between the predicted power components and the expected power components of the three-phase motor in the next voltage period, a value function is constructed; and the action time of the power vector of the power converter is associated with the predicted power components and the value function; Step two, solve the value function and determine the first action time of the power vector of the power converter corresponding to the minimum value function, and determine the first action time as the voltage vector action time in the next voltage period.

[0037] In the embodiment of the present disclosure, the value function can be constructed as the following formula (3).

[0038] (3) wherein, , , , , and are the expected values of the six power components, respectively; the action time , and can be associated with the value function by formula (2), and the values of the first action time , and of the switching state of the next voltage period can be further calculated.

[0039] In yet another embodiment provided by the present disclosure, the three-phase motor power control method further comprises: generating a control signal to control the switching device of the power converter according to the determined voltage vector action time of the next voltage period, adjusting the switching state of the power converter in the next voltage period, and controlling the power components of the three-phase motor in the next voltage period.

[0040] In the embodiment of the present disclosure, according to the values of the first action time , and of the switching state, the corresponding control signal can be generated, and the control signal is output to control the switching state of the power converter. By changing the duration of each switching state, the fluctuation of the grid side output is offset. The purpose of adjusting the power converter according to the voltage condition of the rotor side of the three-phase motor, stabilizing the voltage of each phase of the three-phase motor, and controlling the power of the three-phase motor is achieved.

[0041] In yet another embodiment provided by the present disclosure, the switching state of the power converter comprises: a first switching state, in which the upper switching device of the first bridge arm of the power converter is open, the lower switching device is closed; the upper switching device of the second bridge arm is open, the lower switching device is closed; the upper switching device of the third bridge arm is open, the lower switching device is closed; a second switching state, in which the upper switching device of the first bridge arm of the power converter is open, the lower switching device is closed; the upper switching device of the second bridge arm is open, the lower switching device is closed; the upper switching device of the third bridge arm is closed, the lower switching device is open; a third switching state, in which the upper switching device of the first bridge arm of the power converter is open, the lower switching device is closed; the upper switching device of the second bridge arm is closed, the lower switching device is open; the upper switching device of the third bridge arm is open, the lower switching device is closed; a fourth switching state in which the upper switch device of the first bridge arm of the power converter is open, the lower switch device is closed; the upper switch device of the second bridge arm is closed, the lower switch device is open; the upper switch device of the third bridge arm is closed, the lower switch device is open; a fifth switching state in which the upper switch device of the first bridge arm of the power converter is closed, the lower switch device is open; the upper switch device of the second bridge arm is open, the lower switch device is closed; the upper switch device of the third bridge arm is open, the lower switch device is closed; a sixth switching state in which the upper switch device of the first bridge arm of the power converter is closed, the lower switch device is open; the upper switch device of the second bridge arm is open, the lower switch device is closed; the upper switch device of the third bridge arm is closed, the lower switch device is open; a seventh switching state in which the upper switch device of the first bridge arm of the power converter is closed, the lower switch device is open; the upper switch device of the second bridge arm is closed, the lower switch device is open; the upper switch device of the third bridge arm is open, the lower switch device is closed; an eighth switching state in which the upper switch device of the first bridge arm of the power converter is closed, the lower switch device is open; the upper switch device of the second bridge arm is closed, the lower switch device is open; the upper switch device of the third bridge arm is closed, the lower switch device is open.

[0042] In the embodiments of the present disclosure, the power converter can include three bridge arms, each of which is connected with one phase line on the rotor side of the three-phase motor. After the direct current output by the grid-side power conversion circuit is input to the power converter, the direct current is converted into three-phase alternating current according to a pre-set control strategy by changing the on-off state of each bridge arm. Different voltage vectors can be provided in different on-off states to convert the direct current input to the power converter into alternating current.

[0043] Suppose the on-off state of the first bridge arm is , the on-off state of the second bridge arm is , the on-off state of the third bridge arm is , and the voltage vector provided by the switching state is . Then the voltage vector provided by the first switching state is , the voltage vector provided by the second switching state is , the voltage vector provided by the third switching state is , the voltage vector provided by the fourth switching state is , the voltage vector provided by the fifth switching state is , the voltage vector provided by the sixth switching state is , the voltage vector provided by the seventh switching state is , and the voltage vector provided by the eighth switching state is .

[0044] wherein, and are zero voltage vectors, and the rest are non-zero voltage vectors. In the above equation, 0 represents that the bridge arm is in the on-off state of the upper switch device being closed and the lower switch device being turned off; 1 represents that the bridge arm is in the on-off state of the lower switch device being closed and the upper switch device being turned off.

[0045] In yet another embodiment provided by the present disclosure, the switching state is determined according to a sector in the voltage period; wherein the sector is determined according to the magnitude relationship of each phase voltage in the voltage period; In the case that the first phase voltage is greater than zero, the second phase voltage is less than zero, and the second phase voltage is greater than the third phase voltage, the first sector of the voltage period is determined, and the switching state of the power converter is determined as one of the first switching state, the fifth switching state, the seventh switching state and the eighth switching state; In the case that the first phase voltage is greater than the second phase voltage, the second phase voltage is greater than zero, and the third phase voltage is less than zero, the second sector of the voltage period is determined, and the switching state of the power converter is determined as one of the first switching state, the fifth switching state, the seventh switching state and the eighth switching state; In the case that the second phase voltage is greater than the first phase voltage, the first phase voltage is greater than zero, and the third phase voltage is less than zero, the third sector of the voltage period is determined, and the switching state of the power converter is determined as one of the first switching state, the third switching state, the seventh switching state and the eighth switching state; In the case that the second phase voltage is greater than zero, the first phase voltage is less than zero, and the third phase voltage is less than the first phase voltage, the fourth sector of the voltage period is determined, and the switching state of the power converter is determined as one of the first switching state, the third switching state, the seventh switching state and the eighth switching state; In the case that the second phase voltage is greater than zero, the third phase voltage is less than zero, and the first phase voltage is less than the third phase voltage, the fifth sector of the voltage period is determined, and the switching state of the power converter is determined as one of the first switching state, the third switching state, the fourth switching state and the eighth switching state; In the case that the second phase voltage is greater than the third phase voltage, the third phase voltage is greater than zero, and the first phase voltage is less than zero, the sixth sector of the voltage period is determined, and the switching state of the power converter is determined as one of the first switching state, the third switching state, the fourth switching state and the eighth switching state; In the case that the third phase voltage is greater than the second phase voltage, the second phase voltage is greater than zero, and the first phase voltage is less than zero, the seventh sector of the voltage period is determined, and the switching state of the power converter is determined as one of the first switching state, the second switching state, the fourth switching state and the eighth switching state; In a case that the third phase voltage is greater than zero, the first phase voltage is less than zero, and the first phase voltage is greater than the second phase voltage, a eighth sector of the voltage period is determined, and the switching state of the power converter is determined as one of the first switching state, the second switching state, the fourth switching state and the eighth switching state; In a case that the third phase voltage is greater than zero, the first phase voltage is less than zero, and the second phase voltage is less than the first phase voltage, a ninth sector of the voltage period is determined, and the switching state of the power converter is determined as one of the first switching state, the second switching state, the sixth switching state and the eighth switching state; In a case that the third phase voltage is greater than the first phase voltage, the first phase voltage is greater than zero, and the second phase voltage is less than zero, a tenth sector of the voltage period is determined, and the switching state of the power converter is determined as one of the first switching state, the second switching state, the sixth switching state and the eighth switching state; In a case that the first phase voltage is greater than the third phase voltage, the third phase voltage is greater than zero, and the second phase voltage is less than zero, an eleventh sector of the voltage period is determined, and the switching state of the power converter is determined as one of the first switching state, the fifth switching state, the sixth switching state and the eighth switching state; In a case that the first phase voltage is greater than zero, the third phase voltage is less than zero, and the second phase voltage is less than the third phase voltage, a twelfth sector of the voltage period is determined, and the switching state of the power converter is determined as one of the first switching state, the fifth switching state, the sixth switching state and the eighth switching state.

[0046] In the embodiments of the present disclosure, each voltage period can be divided into 12 sectors as shown in Figure 3 , and the entire voltage period is assumed to be , then each sector is . Each sector corresponds to a different switching state of the power converter, and the power converter can convert direct current into alternating current corresponding to the sector according to different switching states. Through continuous conversion of the switching state of the power converter, the output of alternating current of the complete voltage period is realized.

[0047] Assuming that the first phase voltage in the three-phase alternating current is , the second phase voltage is , and the third phase voltage is . Then in the first sector, ; in the second sector, ; in the third sector, ; in the fourth sector, ; in the fifth sector, ; in the sixth sector, ; in the seventh sector, ; in the eighth sector, ; in the ninth sector, ; in the tenth sector, ; in the eleventh sector, ; in the twelfth sector, .

[0048] For the first sector, voltage vectors , , and may be provided by the first, fifth, seventh and eighth switching states, respectively.

[0049] For the second sector, voltage vectors , , and may be provided by the first, fifth, seventh and eighth switching states, respectively.

[0050] For the third sector, voltage vectors , , and may be provided by the first, third, seventh and eighth switching states, respectively.

[0051] For the fourth sector, voltage vectors , , and may be provided by the first, third, seventh and eighth switching states, respectively.

[0052] For the fifth sector, voltage vectors , , and may be provided by the first, third, fourth and eighth switching states, respectively.

[0053] For the sixth sector, voltage vectors , , and may be provided by the first, third, fourth and eighth switching states, respectively.

[0054] For the seventh sector, voltage vectors , , and may be provided by the first, second, fourth and eighth switching states, respectively.

[0055] For the eighth sector, the voltage vectors , , and may be provided by the first switching state, the second switching state, the fourth switching state and the eighth switching state, respectively.

[0056] For the ninth sector, the voltage vectors , , and may be provided by the first switching state, the second switching state, the sixth switching state and the eighth switching state, respectively.

[0057] For the tenth sector, the voltage vectors , , and may be provided by the first switching state, the second switching state, the sixth switching state and the eighth switching state, respectively.

[0058] For the eleventh sector, the voltage vectors , , and may be provided by the first switching state, the fifth switching state, the sixth switching state and the eighth switching state, respectively.

[0059] For the twelfth sector, the voltage vectors , , and may be provided by the first switching state, the fifth switching state, the sixth switching state and the eighth switching state, respectively.

[0060] In the case where the alternating current of a certain sector needs to be output, one of the switching states corresponding to the non-zero voltage vectors in the corresponding switching state is selected, the voltage vector provided by the switching state is marked as , and the duration of the switching state is determined as ; the voltage vector provided by the switching state corresponding to the other non-zero voltage vector is marked as , and the duration of the switching state is determined as ; one of the switching states corresponding to the zero voltage vectors in the corresponding switching state is selected, the voltage vector provided by the switching state is marked as , and the duration of the switching state is determined as . Wherein, , is the total time corresponding to one sector.

[0061] By controlling the duration of different switching states, the power converter can convert the input DC power into three-phase AC power.

[0062] In another embodiment provided by the present disclosure, the power control amount of the switching state is determined by a motor power prediction model based on the positive-sequence and negative-sequence voltage components of the voltage cycle, and the switching state voltage control amount; wherein, the switching state voltage control amount is determined based on the input voltage and switching state of the power converter.

[0063] In the embodiment of the present disclosure, in the above formula (2), 、 、 、 、 and , is the variation of the voltage vector provided to the six power components in different switching states, which can be determined according to the following formula (4).

[0064] (4) In the above formula (4), 、 、 and Represent the positive and negative sequence components of voltage respectively 、 、 and The square operation of , In different voltage vectors The control quantity under the action of and The value of . and The values ​​under different voltage vectors are: When operating the switch vector hour, The value of , The value of ; When operating the switch vector hour, The value of , The value of ; When operating the switch vector hour, The value of , The value is 0; when the switch vector hour, The value of , The value is 0; when the switch vector Time, The value of , The value of ; when the operation switch vector , The value of , The value of ; when the operation switch vector Or the operation switch vector , And The value is 0.

[0065] In combination with the above formula (1)-(4), the loss function in formula (3) Based on the loss function The partial derivative of And , as shown in the following formula (5) and formula (6).

[0066] (5) (6) In the above two formulas, Indicates the partial derivative of the action time T 1; Indicates the partial derivative of the action time T 2.

[0067] In combination with and solving the above formula (1)-formula (6), we can get , .

[0068] Among them, ; ; ; ; ; .

[0069] Further, ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; .

[0070] The value of , , can be calculated by the above formula, and the final , , is the first action time , and . Further, according to the first action time, the corresponding control signal is generated to control the switching state of the voltage source converter.

[0071] In yet another embodiment of the present disclosure, the three-phase motor parameters include: the equivalent resistance value of the three-phase motor and the input inductance value of the three-phase motor.

[0072] An example of simulation is provided here to illustrate the effect of power control using the present method. It is assumed that the three-phase voltages output by the power converter in the current period are , , , so that the three-phase motor rotor side is in a three-phase unbalanced state; the angular frequency is ; the equivalent value of the inductance of the three-phase motor rotor side is ; the equivalent resistance of the three-phase motor rotor side is ; the filter capacitor connected to the DC side of the power converter is ; the DC side load is is ; the control period is , the initial is , P c2r , P s2r , , , are all 0.

[0073] In this example, the three-phase motor can be selected as a doubly-fed motor. The simulation waveform diagram of the voltage and current output by the power converter is shown in Figure 4 , the vertical coordinate is divided into voltage value and current value units, which are volts ( ) and amperes ( ) respectively; the horizontal coordinate is time, which is seconds ( ). It can be seen that the output three-phase alternating current is sinusoidal but the amplitude is unbalanced, and the amplitude difference between each phase is Left and right.

[0074] Figure 5 For the doubly-fed motor under sub-synchronous operation, the output slip power rectification is a DC voltage waveform diagram, the vertical coordinate is voltage, which can be volt ( ); the horizontal coordinate is time, which can be seconds ( ). It can be seen that through the control of the method, the output waveform can enter a steady state in around, and is stabilized in .

[0075] Figure 6 For the average value of active power and reactive power output by the power converter after the doubly-fed motor enters a steady state, the waveform diagram is shown in the figure, the vertical coordinate is reactive power and active power, which can be var ( ) and watt ( ) respectively; the horizontal coordinate is time, which can be seconds ( ). Figure 6 In the figure, the black solid line is the average value of active power, and the gray dashed line is the average value of reactive power. The average value of active power fluctuates in , the average value of reactive power fluctuates in , which achieves the purpose of tracking control of expected active and reactive power.

[0076] Figure 7 For the active power and reactive power sine and cosine components of the power converter, the waveform diagram is shown in the figure, wherein the vertical coordinate is reactive power and active power, which can be var ( ) and watt ( ) respectively; the horizontal coordinate is time, which can be seconds ( ). It can be seen that after the doubly-fed motor enters a steady state, the active power cosine second component fluctuates between and , the active power sine second component fluctuates between and , the reactive power cosine second component fluctuates between and , and the reactive power sine second component fluctuates between and , all of which fluctuate in or around, which shows that the disclosure can well suppress the positive and negative components of the power converter output power to the rotor side of the three-phase motor under the condition of unbalanced three-phase power grid.

[0077] The embodiment of the disclosure also provides a three-phase motor power control device, as shown in Figure 8 , comprising: The model construction module 801 is configured to substitute the three-phase motor parameter into a preset motor power prediction model to construct a motor power prediction model for the current three-phase motor. The prediction module 802 is configured to acquire positive sequence electrical signal components and negative sequence electrical signal components of each phase of the current three-phase motor and a switching state of a power supply converter supplying power to the three-phase motor, and predict a predicted power component of the three-phase motor in a next voltage period through the motor power prediction model. The determination module 803 is configured to determine a voltage vector action time for the power supply converter in the next voltage period according to the predicted power component.

[0078] In yet another embodiment provided by the present disclosure, the prediction module 802 is further configured to determine a current power component of the three-phase motor in a current voltage period through the motor power prediction model by using the acquired positive sequence electrical signal components and negative sequence electrical signal components of each phase of the current three-phase motor and the current switching state of the power supply converter; and predict a power component of the three-phase motor in a next voltage period according to the current power component, a power control amount and an action time of the current switching state of the power supply converter.

[0079] In yet another embodiment provided by the present disclosure, the determination module 803 is further configured to construct a value function based on an error between the predicted power component and an expected power component of the three-phase motor in the next voltage period; and associate the action time of the power supply vector of the power supply converter with the predicted power component and the value function; solve the value function and determine a first action time of the power supply vector of the power supply converter corresponding to a minimum value of the value function, and determine the first action time as the voltage vector action time in the next voltage period.

[0080] In yet another embodiment provided by the present disclosure, the three-phase motor power control device further includes a control module 804 configured to generate a control signal to control a switching device of the power supply converter according to the determined voltage vector action time in the next voltage period, adjust the switching state of the power supply converter in the next voltage period, and control the power component of the three-phase motor in the next voltage period.

[0081] Through the above description of the embodiments, those skilled in the art can clearly understand that the embodiments of the present disclosure can be implemented by hardware, or by means of software and a necessary general hardware platform. Based on such understanding, the technical solutions of the embodiments of the present disclosure can be embodied in the form of a software product, which can be stored in a non-volatile storage medium (which can be a CD-ROM, a U disk, a mobile hard disk, etc.), and includes a number of instructions to make a computer device (which can be a personal computer, a server, or a network device, etc.) execute the methods described in the embodiments of the present disclosure.

[0082] Those skilled in the art can understand that the modules or flows in the drawings are not necessarily required for implementing the present disclosure.

[0083] Those skilled in the art can understand that the modules in the devices in the embodiments can be distributed in the devices in the embodiments according to the embodiment description, or can be changed to be located in one or more devices different from the embodiments. The modules in the above embodiments can be combined into one module, or can be further split into multiple sub-modules.

[0084] The above sequence numbers of the embodiments of the present disclosure are only for description, and do not represent the advantages and disadvantages of the embodiments.

[0085] Obviously, those skilled in the art can make various modifications and variations to the present disclosure without departing from the spirit and scope of the present disclosure. Thus, if these modifications and variations of the present disclosure belong to the scope of the claims of the present disclosure and the equivalent technologies thereof, the present disclosure also intends to include these modifications and variations.

Claims

1. A three-phase motor power control method, characterized in that: include: Substituting the three-phase motor parameters into a preset motor power prediction model to construct a motor power prediction model for the current three-phase motor; wherein the preset motor power prediction model is used to establish a numerical association between the electrical signal components on the rotor side of the three-phase motor and the power components of the three-phase motor; Respectively obtain the positive-sequence electrical signal component and the negative-sequence electrical signal component of each phase of the current three-phase motor, as well as the switching state of the power converter supplying power to the three-phase motor, and predict the predicted power component of the three-phase motor in the next voltage cycle using the motor power prediction model; A voltage vector action time for a next voltage cycle of the power converter is determined according to the predicted power component.

2. The method according to claim 1, wherein The preset motor power prediction model is: ； in, is the equivalent resistance value of the three-phase motor rotor side; is the equivalent inductance value of the rotor side of the three-phase motor; is the angular frequency of the three-phase AC voltage on the rotor side of the three-phase motor; 、 、 、 、 and are the power components on the rotor side of the three-phase motor respectively; 、 、 、 、 and are the derivatives of the power components on the rotor side of the three-phase motor respectively; 、 、 and They are the electrical signal components on the rotor side of the three-phase motor; and are the control quantities of the power converter respectively.

3. The method according to claim 1, wherein The method of respectively obtaining the positive-sequence electrical signal component and the negative-sequence electrical signal component of each phase of the current three-phase motor and the switching state of the power converter supplying power to the three-phase motor, and predicting the predicted power component of the three-phase motor in the next voltage cycle by using the motor power prediction model, includes: Determine the current power component of the three-phase motor in the current voltage cycle using the motor power prediction model based on the obtained positive-sequence electrical signal component and negative-sequence electrical signal component of each phase of the three-phase motor and the current switching state of the power converter; The power component of the next voltage cycle of the three-phase motor is predicted based on the current power component and the power control amount and action time of the current switching state of the power converter.

4. The method according to claim 1, wherein Determining a voltage vector action time for a next voltage cycle of the power converter according to the predicted power component includes: constructing a cost function based on an error between a predicted power component and an expected power component of the three-phase motor in the next voltage cycle; and associating an action time of a power vector of a power converter with the cost function via the predicted power component; The cost function is solved, and a first action time of a power vector of the power converter corresponding to minimizing the cost function is determined, and the first action time is determined as the voltage vector action time of the next voltage cycle.

5. The method according to claim 1, wherein Also includes: According to the determined voltage vector action time of the next voltage cycle, a control signal is generated to control the switching device of the power converter, adjust the switching state of the power converter in the next voltage cycle, and control the power component of the three-phase motor in the next voltage cycle.

6. The method according to claim 2, wherein The switching state of the power converter includes: In the first switching state, the upper switch device of the first bridge arm of the power converter is disconnected and the lower switch device is closed; the upper switch device of the second bridge arm is disconnected and the lower switch device is closed; the upper switch device of the third bridge arm is disconnected and the lower switch device is closed; In the second switching state, the upper switch device of the first bridge arm of the power converter is disconnected and the lower switch device is closed; the upper switch device of the second bridge arm is disconnected and the lower switch device is closed; the upper switch device of the third bridge arm is closed and the lower switch device is disconnected; In a third switching state, the upper switch device of the first bridge arm of the power converter is disconnected and the lower switch device is closed; the upper switch device of the second bridge arm is closed and the lower switch device is disconnected; and the upper switch device of the third bridge arm is disconnected and the lower switch device is closed; In a fourth switching state, the upper switch device of the first bridge arm of the power converter is disconnected and the lower switch device is closed; the upper switch device of the second bridge arm is closed and the lower switch device is disconnected; and the upper switch device of the third bridge arm is closed and the lower switch device is disconnected. In a fifth switching state, the upper switching device of the first bridge arm of the power converter is closed and the lower switching device is open; the upper switching device of the second bridge arm is open and the lower switching device is closed; and the upper switching device of the third bridge arm is open and the lower switching device is closed. In a sixth switching state, the upper switch device of the first bridge arm of the power converter is closed, and the lower switch device is opened; the upper switch device of the second bridge arm is opened, and the lower switch device is closed; and the upper switch device of the third bridge arm is closed, and the lower switch device is opened. In a seventh switching state, the upper switch device of the first bridge arm of the power converter is closed, and the lower switch device is opened; the upper switch device of the second bridge arm is closed, and the lower switch device is opened; the upper switch device of the third bridge arm is opened, and the lower switch device is closed; In the eighth switching state, the upper switch device of the first bridge arm of the power converter is closed and the lower switch device is open; the upper switch device of the second bridge arm is closed and the lower switch device is open; the upper switch device of the third bridge arm is closed and the lower switch device is open.

7. The method according to claim 5, wherein The switch state is determined according to a sector in a voltage cycle; wherein the sector is determined according to a magnitude relationship of each phase voltage in the voltage cycle; When the first phase voltage is greater than zero, the second phase voltage is less than zero, and the second phase voltage is greater than the third phase voltage, determining it as the first sector of the voltage cycle, and determining the switching state of the power converter to be one of the first switching state, the fifth switching state, the seventh switching state, and the eighth switching state; When the first phase voltage is greater than the second phase voltage, the second phase voltage is greater than zero, and the third phase voltage is less than zero, determining it as a second sector of the voltage cycle, and determining the switching state of the power converter to be one of the first switching state, the fifth switching state, the seventh switching state, and the eighth switching state; When the second phase voltage is greater than the first phase voltage, the first phase voltage is greater than zero, and the third phase voltage is less than zero, determining it as a third sector of the voltage cycle, and determining the switching state of the power converter to be one of the first switching state, the third switching state, the seventh switching state, and the eighth switching state; When the second phase voltage is greater than zero, the first phase voltage is less than zero, and the third phase voltage is less than the first phase voltage, determining it as a fourth sector of the voltage cycle, and determining the switching state of the power converter to be one of the first switching state, the third switching state, the seventh switching state, and the eighth switching state; When the second phase voltage is greater than zero, the third phase voltage is less than zero, and the first phase voltage is less than the third phase voltage, determining it as a fifth sector of the voltage cycle, and determining the switching state of the power converter to be one of the first switching state, the third switching state, the fourth switching state, and the eighth switching state; When the second phase voltage is greater than the third phase voltage, the third phase voltage is greater than zero, and the first phase voltage is less than zero, determining it as a sixth sector of the voltage cycle, and determining the switching state of the power converter to be one of the first switching state, the third switching state, the fourth switching state, and the eighth switching state; When the third phase voltage is greater than the second phase voltage, the second phase voltage is greater than zero, and the first phase voltage is less than zero, determining it as the seventh sector of the voltage cycle, and determining the switching state of the power converter to be one of the first switching state, the second switching state, the fourth switching state, and the eighth switching state; When the third phase voltage is greater than zero, the first phase voltage is less than zero, and the first phase voltage is greater than the second phase voltage, determining it as the eighth sector of the voltage cycle, and determining the switching state of the power converter to be one of the first switching state, the second switching state, the fourth switching state, and the eighth switching state; When the third phase voltage is greater than zero, the first phase voltage is less than zero, and the second phase voltage is less than the first phase voltage, determining it as a ninth sector of the voltage cycle, and determining the switching state of the power converter to be one of the first switching state, the second switching state, the sixth switching state, and the eighth switching state; When the third phase voltage is greater than the first phase voltage, the first phase voltage is greater than zero, and the second phase voltage is less than zero, determining it as the tenth sector of the voltage cycle, and determining the switching state of the power converter to be one of the first switching state, the second switching state, the sixth switching state, and the eighth switching state; When the first phase voltage is greater than the third phase voltage, the third phase voltage is greater than zero, and the second phase voltage is less than zero, determining it as the eleventh sector of the voltage cycle, and determining the switching state of the power converter to be one of the first switching state, the fifth switching state, the sixth switching state, and the eighth switching state; When the first phase voltage is greater than zero, the third phase voltage is less than zero, and the second phase voltage is less than the third phase voltage, it is determined to be the twelfth sector of the voltage cycle, and the switching state of the power converter is determined to be one of the first switching state, the fifth switching state, the sixth switching state and the eighth switching state.

8. The method according to claim 2, wherein The power control amount of the switching state is determined by the motor power prediction model according to the positive sequence and negative sequence voltage components of the voltage cycle and the switching state voltage control amount; wherein, the switching state voltage control amount is determined according to the input voltage and switching state of the power converter.

9. The method according to claim 1, wherein The three-phase motor parameters include: the equivalent resistance value of the three-phase motor and the input inductance value of the three-phase motor.

10. A three-phase motor power control device, characterized in that: include: A model building module is used to substitute the three-phase motor parameters into a preset motor power prediction model to build a motor power prediction model for the current three-phase motor; a prediction module, configured to respectively obtain the positive-sequence electrical signal component and the negative-sequence electrical signal component of each phase of the current three-phase motor, and the switching state of the power converter supplying power to the three-phase motor, and predict the predicted power component of the three-phase motor in the next voltage cycle using the motor power prediction model; A determination module is configured to determine a voltage vector action time for a next voltage cycle of the power converter according to the predicted power component.

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