A high-voltage asynchronous motor control system

Abstract

The application belongs to the technical field of motor control systems, and specifically discloses a high-voltage asynchronous motor control system, which comprises a PLC, a three-phase acquisition unit, a coordinate transformation unit, an adaptive state observation unit and a modulation control unit. The modulation control unit converts a modulation control signal into a control driving signal. The three-phase acquisition unit is used for acquiring three-phase voltage, three-phase current and motor speed and sending them to the coordinate transformation unit. The coordinate transformation unit converts the three-phase voltage and three-phase current signals into mt-axis signals. The coordinate transformation unit is connected with the adaptive state observation unit and the modulation control unit. The adaptive state observation unit adaptively acquires working states and dynamic parameter models and sends them to the modulation control unit. The dynamic parameters of the certainty and uncertainty of the high-voltage asynchronous motor are dynamically estimated, so that the control driving signal of the three-phase cascade power stage is generated in the modulation control unit, and then the requirements of various parts are coordinated, and the energy-saving control requirements of the high-voltage asynchronous motor in the production process are met.

Description

Technical Field

[0001] This invention belongs to the field of motor control system technology, and particularly relates to a high-voltage asynchronous motor control system. Background Technology

[0002] An asynchronous motor, also known as an induction motor, is a motor in which the rotor is placed in a rotating magnetic field. Under the influence of this magnetic field, the rotor gains a torque, causing it to rotate. Depending on the type of alternating current used, motors are classified as single-phase or three-phase. Single-phase motors are used in applications such as washing machines and electric fans; three-phase motors are used as power equipment in factories. Three-phase asynchronous motors, and indeed almost all asynchronous motors, are the main power source devices in modern production enterprises such as power plants, cement plants, and mines. In practical applications, they commonly suffer from problems of excessive energy supply and low energy conversion efficiency, resulting in significant energy waste. This is particularly true for high-voltage motors, where the energy consumption and impact on the power grid are especially severe.

[0003] Existing technologies have addressed this issue extensively. For example, various baffles are used to regulate airflow in fan control based on production process requirements, throttle valves are used to regulate flow in water pump control, constant voltage-frequency ratio is used to control motor speed, and frequency conversion control is used to upgrade motor control. However, some methods, while improving process efficiency to some extent, fail to effectively regulate motor speed, thus not improving energy consumption. Other methods, such as using newer constant voltage-frequency ratio or frequency conversion control, face challenges with high-voltage asynchronous motors. Firstly, the equipment is expensive, power-stage components are demanding, and harmonic interference in motor control leads to easy wear and tear on power devices, making maintenance and replacement difficult, resulting in low cost-effectiveness. Secondly, these controllers rarely integrate the actual production process with motor control. Furthermore, high-voltage asynchronous motors are highly coupled high-voltage motor models with structural, electrical parameters, and environmental temperature and humidity factors. They also operate at high voltage and power, making measurement difficult. Therefore, the influence of time-varying high-voltage motor models is rarely considered in the control of this type of motor. Summary of the Invention

[0004] The purpose of this invention is to provide a high-voltage asynchronous motor control system to solve the problem that existing technologies cannot truly achieve stable and reliable energy-saving control goals.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows: a high-voltage asynchronous motor control system, comprising a PLC, a three-phase acquisition unit, a coordinate transformation unit, an adaptive state observation unit, and a modulation control unit. The high-voltage asynchronous motor is provided with driving voltage and power by a three-phase cascaded power stage structure. The PLC receives production instructions from the upper level and converts them into modulation control instructions, which are then sent to the modulation control unit. The modulation control unit converts the modulation control signals into control drive signals and sends them to the three-phase cascaded power stage structure. The three-phase cascaded power stage structure drives the production equipment linked to the high-voltage asynchronous motor to operate. The three-phase acquisition unit is used to acquire the three-phase voltage, three-phase current, and motor speed of the high-voltage asynchronous motor during operation and sends the acquired data to the coordinate transformation unit. The coordinate transformation unit converts the three-phase voltage and three-phase current signals into mt-axis signals. The coordinate transformation unit sends the converted mt-axis signals and motor speed to the adaptive state observation unit and the modulation control unit. The adaptive state observation unit adaptively acquires the operating state and dynamic parameter model of the high-voltage asynchronous motor and sends them to the modulation control unit. The modulation control unit generates the control drive signals according to the modulation control instructions and the operating state and dynamic parameter model of the high-voltage asynchronous motor.

[0006] Furthermore, the three-phase cascaded power stage structure includes a DC bus, several half-bridge SM sub-modules or several full-bridge SM sub-modules. The DC bus forms a three-phase inverter circuit through several half-bridge SM sub-modules or several full-bridge SM sub-modules. Each phase uses 2N half-bridge SM sub-modules or 2N full-bridge SM sub-modules. The 2N half-bridge SM sub-modules or 2N full-bridge SM sub-modules of each phase form two branches. Each branch is equipped with a reactor and an equivalent resistance. The two branches of each phase are connected to a high-voltage asynchronous motor after merging. Each half-bridge SM sub-module or full-bridge SM sub-module is equipped with a set of power capacitors for energy storage. Each half-bridge SM sub-module or full-bridge SM sub-module is connected to a modulation control unit.

[0007] Furthermore, each phase uses a sinusoidal signal as the basic modulation signal, and each half-bridge SM submodule or full-bridge SM submodule in the same phase uses two triangular waves as carrier signals. The basic modulation signals between different phases are 120 degrees out of phase. The basic modulation signals between adjacent half-bridge SM submodules or adjacent full-bridge SM submodules are π / 2N out of phase, and the two carrier signals of the same half-bridge SM submodule or full-bridge SM submodule are π out of phase.

[0008] Furthermore, the adaptive state observation unit includes an m-axis observation structure and a t-axis observation structure. Both the m-axis and t-axis observation structures include an ASO observer and a controller. The ASO observer sends the observed data to the controller. The high-voltage motor model in the ASO observer can be represented as:

[0009]

[0010] Among them, i sm i represents the current along the m-axis in the mt coordinate system. st This represents the current along the t-axis in the mt coordinate system; u sm U represents the voltage along the m-axis in the mt coordinate system. sr Let ψ represent the voltage along the t-axis in the mt coordinate system; since the m-axis coincides with the rotor flux linkage vector, ψ is used. r Indicates the m-axis; L m L represents the mutual inductance between the coaxial equivalent windings of the stator and rotor; s L represents the self-inductance of the equivalent two-phase stator winding. r R represents the self-inductance of the rotor's equivalent two-phase winding; s R represents the stator winding resistance. r The rotor winding resistance is represented by σ, the motor leakage flux coefficient, and T. r ω is the rotor electromagnetic time constant; ω1 is the rotational angular velocity of the dq rotating orthogonal coordinate axis relative to the stator; ω is the rotational speed of the high-voltage asynchronous motor;

[0011] Use Δ sm and Δ st To represent the uncertainty of the high-voltage motor model, the high-voltage motor model is further expressed as the following nonlinear model:

[0012]

[0013] in,

[0014] According to formula (2), the models of the two subsystems, m-axis and t-axis, are defined as follows:

[0015]

[0016]

[0017] Based on formulas (3) and (4), the algorithm model for the ASO observer is as follows:

[0018]

[0019]

[0020] The total disturbance model can be obtained from formulas (5) and (6):

[0021]

[0022] Where, β sm and β st Observed by the ASO observer;

[0023] f aso Defined as:

[0024]

[0025] Where δ is the deviation between the ASO observer output and the true value; sgn(δ) indicates the sign of δ; α is used to adjust f aso The gain is λ, where λ is the error coefficient used to adjust the magnitude of the error.

[0026] Furthermore, the controller employs a high-voltage motor controller, and the design method of the high-voltage motor controller includes hysteresis and SVPWM.

[0027] Furthermore, the voltage of the half-bridge SM submodule and the full-bridge SM submodule is 1200V to 1700V.

[0028] Furthermore, the modulation control unit generates the basic modulation signal and the control drive signal based on the modulation control command and the operating state and dynamic parameter model of the high-voltage asynchronous motor.

[0029] Furthermore, the modulation control unit is connected to the three-phase cascaded power stage structure via optical fiber.

[0030] The beneficial effects of this technical solution are as follows: ① This technical solution can integrate the technical parameters and production command requirements of each link in the power equipment production process of modern production enterprises such as power plants, cement plants, and mines, and dynamically predict the deterministic and uncertain parameters of high-voltage asynchronous motors. This allows the modulation and control unit to generate control drive signals for a three-phase cascaded power level, thereby coordinating the needs of each part and achieving the energy-saving control requirements of the high-voltage asynchronous motor during the production process. Simultaneously, it ensures low-harmonic operation during the start-up, shutdown, and operation of the high-power motor, improving the stability and safety of the motor power supply network. ② When the parameters of the high-voltage asynchronous motor cannot be accurately obtained, the ASO observer algorithm adaptively acquires the operating state of the high-voltage asynchronous motor based on the operating voltage, current, and speed signals. It uniformly describes the uncertainties of the high-voltage motor model as a dynamic parameter model represented by "total disturbance." Therefore, the ASO observer can adaptively satisfy the dynamic disturbance characteristics of the high-voltage motor model, working together with the modulation and control unit to achieve stable, efficient, and energy-saving operation of the high-voltage asynchronous motor. ③ This technical solution can use a lower-frequency half-bridge SM submodule or a full-bridge SM submodule to drive the signal and generate a higher-frequency phase modulation wave. Therefore, the modulation wave has less low-order harmonic content, while high-order harmonics cannot pass through the low-pass filter formed by the circuit and the armature inductance of the high-voltage asynchronous motor, and are thus naturally eliminated. Therefore, low-harmonic distortion control of a high-voltage asynchronous motor can be achieved using a relatively inexpensive low-frequency SM submodule. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of a high-voltage asynchronous motor control system according to the present invention;

[0032] Figure 2 for Figure 1 Schematic diagram of a three-phase cascaded power stage structure;

[0033] Figure 3 for Figure 1 Timing diagram of SM submodule modulation in the middle half-bridge or full-bridge;

[0034] Figure 4 for Figure 3 A schematic diagram of the single-phase output signal of a three-phase cascaded power stage structure;

[0035] Figure 5 for Figure 1 A diagram illustrating the structure of the adaptive state observation unit;

[0036] Figure 6 for Figure 5 Algorithm flowchart of the adaptive state observation unit;

[0037] Figure 7 for Figure 6 A schematic diagram of the total perturbation model characteristics of the adaptive state observation unit. Detailed Implementation

[0038] The following detailed description illustrates the specific implementation method:

[0039] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] The basic implementation examples are as follows: Figure 1-7The diagram illustrates a high-voltage asynchronous motor control system, comprising a PLC, a three-phase data acquisition unit, a coordinate transformation unit, an adaptive state observation unit, and a modulation control unit. The high-voltage asynchronous motor is driven by a three-phase cascaded power stage structure, which provides the necessary voltage and power. The PLC receives process parameters collected from various stages of the production process and production instructions from higher-level units, converts these into modulation control instructions, and sends them to the modulation control unit. The modulation control unit is connected to the three-phase cascaded power stage structure via optical fiber. The modulation control unit converts the modulation control signals into control drive signals and sends them to the three-phase cascaded power stage structure, which then drives the high-voltage asynchronous motor-driven production equipment. The three-phase acquisition unit collects the three-phase voltage, three-phase current, and motor speed of the high-voltage asynchronous motor during operation (using voltage sensors, current sensors, and speed sensors) and sends the collected data to the coordinate transformation unit. The coordinate transformation unit converts the three-phase voltage and three-phase current signals into mt-axis signals. The coordinate transformation unit then sends the converted mt-axis signals and motor speed to the adaptive state observation unit and the modulation control unit. The adaptive state observation unit adaptively acquires the operating state and dynamic parameter model of the high-voltage asynchronous motor and sends it to the modulation control unit. The modulation control unit generates basic modulation signals and control drive signals based on the modulation control command and the operating state and dynamic parameter model of the high-voltage asynchronous motor.

[0041] like Figure 3 As shown, the three-phase cascaded power stage structure includes a DC bus (voltage V). dc (O point is the hypothetical midpoint voltage), several half-bridge SM sub-modules (half-bridge IGBT modules, etc.) or several full-bridge SM sub-modules (full-bridge IGBT modules, etc.), the DC bus forms a three-phase inverter circuit through several half-bridge SM sub-modules or several full-bridge SM sub-modules, providing AC current for the high-voltage asynchronous motor M to operate.

[0042] Each phase employs 2N half-bridge SM submodules or 2N full-bridge SM submodules. Therefore, each half-bridge SM submodule or full-bridge SM submodule only withstands 1 / 2N of the high-voltage bus voltage, allowing the use of IGBT modules of conventional voltage levels. The 2N half-bridge SM submodules or 2N full-bridge SM submodules in each phase form two branches, each equipped with a reactor L and an equivalent resistance R. The two branches of each phase merge and connect to the high-voltage asynchronous motor. The reactor L in each phase prevents sudden changes in phase current, such as current surges during short circuits and sudden motor unloading, preventing pump-generated voltage and protecting all power devices from excessive bus voltage. It also suppresses interphase circulating current. Each half-bridge SM submodule or full-bridge SM submodule is equipped with a set of power capacitors for energy storage, absorbing or replenishing energy during the motor's transient operation. Each half-bridge SM submodule or full-bridge SM submodule is connected to the modulation and control unit via optical fiber, providing control signals while ensuring electrical isolation from the control section. The voltage of the half-bridge SM submodule or the full-bridge SM submodule is 1200V to 1700V. The power module can be added or removed arbitrarily according to the voltage level, power (current) requirements, and motor operation harmonic control requirements to meet the technical requirements of drive voltage and power of high-voltage asynchronous motor.

[0043] Each phase uses a sinusoidal signal as the basic modulation signal. Within the same phase, each half-bridge or full-bridge SM submodule uses two triangular waves as carrier signals. The basic modulation signals between different phases differ by 120 degrees. Figure 3 As shown; the basic modulation signals between adjacent half-bridge SM submodules or adjacent full-bridge SM submodules differ by π / 2N, and the two carrier signals within the same half-bridge SM submodule or full-bridge SM submodule differ by π. Assuming the carrier signal frequency is f1 and the sine wave frequency is f2, then the carrier ratio is N. p =f1 / f2 (f1>f2), the generated equivalent control drive signal frequency f per phase p =2Nf1N p >>f1, and the control drive signal frequency of each half-bridge or full-bridge SM submodule is f1, thus achieving a higher three-phase control drive frequency with a lower drive signal frequency, such as... Figure 4 As shown. Therefore, a higher frequency phase modulation wave can be generated using a lower frequency half-bridge or full-bridge drive signal. Consequently, the modulation wave has less low-order harmonic content, while high-order harmonics cannot pass through the low-pass filter formed by the circuit and the armature inductance of the high-voltage asynchronous motor, and are thus naturally eliminated. Therefore, low-harmonic distortion control of a high-voltage asynchronous motor can be achieved using relatively inexpensive low-frequency IGBT modules.

[0044] The adaptive state observation unit includes an m-axis observation structure and a t-axis observation structure. Both structures include an ASO observer and a controller. The ASO observer sends the observed data to the controller. The controller employs a high-voltage motor controller. The design methods for high-voltage motor controllers include hysteresis and SVPWM, both well-known and commonly used methods, which will not be discussed here. The high-voltage motor model in the ASO observer can be represented as:

[0045]

[0046] Among them, i sm i represents the current along the m-axis in the mt coordinate system. st This represents the current along the t-axis in the mt coordinate system; u sm U represents the voltage along the m-axis in the mt coordinate system. st Let ψ represent the voltage along the t-axis in the mt coordinate system; since the m-axis coincides with the rotor flux linkage vector, ψ is used. r L represents the m-axis (i.e., the magnitude of the composite vector in the αβ coordinate system); m L represents the mutual inductance between the coaxial equivalent windings of the stator and rotor; s L represents the self-inductance of the equivalent two-phase stator winding. r R represents the self-inductance of the rotor's equivalent two-phase winding; s R represents the stator winding resistance. r The rotor winding resistance is represented by σ, the motor leakage flux coefficient, and T. r ω is the rotor electromagnetic time constant; ω1 is the rotational angular velocity of the dq rotating orthogonal coordinate axis relative to the stator; ω is the rotational speed of the high-voltage asynchronous motor;

[0047] Due to the motor parameter L in the high-voltage motor model m L s L r R s and R r , and σ and T represented by them r They are mutually coupled, and their temperature varies with the operating state of the high-voltage asynchronous motor and the temperature of the magnetic core and windings inside the high-voltage asynchronous motor. This is represented by Δ. sm and Δ st To represent the uncertainty of the high-voltage motor model, the high-voltage motor model is further expressed as the following nonlinear model:

[0048]

[0049] in,

[0050] f sm and f stThe total disturbance model includes the voltage drop caused by stator and rotor resistance and mutual and self-inductance, flux linkage effects, cross-coupling terms, unmodeled dynamic models, uncertainties, and external disturbances (including various temperature uncertainties). Based on this, the models of the two subsystems on the m-axis and t-axis are defined:

[0051]

[0052]

[0053] Based on formulas (3) and (4), the algorithm model for the ASO observer is as follows:

[0054]

[0055]

[0056] The total disturbance model can be obtained from formulas (5) and (6):

[0057]

[0058] Where, β sm and β st Observed by the ASO observer, the ASO observer model is as follows: Figure 5 As shown;

[0059] The flowchart of the ASO observer algorithm is as follows: Figure 6 As shown, fx so Defined as:

[0060]

[0061] Where δ is the deviation between the ASO observer output and the true value; sgn(δ) indicates the sign of δ; α is used to adjust f aso The gain is denoted by λ, which is the error coefficient used to adjust the error magnitude. For example, when α = 0.5 and λ = 5000, f... aso Curves Figure 7 As shown.

[0062] Specifically, f aso The curve is smooth, and the ASO observer adjustment process is continuous and stable. The ASO observer adjustment function can be completed using a single function expression.

[0063] When the deviation |δ| is small, f aso A larger rate of change allows for rapid convergence near steady state, unlike the integral element of a PID-type observer which can produce steady-state error or integral saturation; simultaneously, f aso The rate of change is not particularly large, thus avoiding abrupt oscillations when the ASO observer bias changes sign near zero.

[0064] When the deviation |δ| is large, f aso The change is not significant. The ASO observer approximates the true value at a relatively stable rate, avoiding the problem of excessive gain and large overshoot caused by the large error of traditional PID-type observers.

[0065] In the above examples, the specific values ​​of parameters α and λ are only used to illustrate the principle of the present invention. In practice, different combinations of α and λ values ​​can be selected according to different applications.

[0066] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0067] The above descriptions are merely embodiments of the present invention. Commonly known structures and characteristics are not described in detail here. Those skilled in the art are aware of all common technical knowledge in the field prior to the application date or priority date, are aware of all existing technologies in that field, and have the ability to apply conventional experimental methods prior to that date. Those skilled in the art can, under the guidance of this application, improve and implement this solution in combination with their own capabilities. Some typical known structures or methods should not be obstacles for those skilled in the art to implement this application. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of the present invention. These should also be considered within the scope of protection of the present invention, and will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A high-voltage asynchronous motor control system, characterized in that: The system includes a PLC, a three-phase acquisition unit, a coordinate transformation unit, an adaptive state observation unit, and a modulation control unit. The high-voltage asynchronous motor is driven by a three-phase cascaded power stage structure, which provides the necessary voltage and power. The PLC receives production instructions from its superior unit, converts them into modulation control instructions, and sends these instructions to the modulation control unit. The modulation control unit converts the modulation control signals into control drive signals and sends them to the three-phase cascaded power stage structure, which drives the high-voltage asynchronous motor-linked production equipment. The three-phase acquisition unit collects the three-phase voltage, three-phase current, and motor speed of the high-voltage asynchronous motor during operation and sends the collected data to the coordinate transformation unit. The coordinate transformation unit converts the three-phase voltage and current signals into mt-axis signals and sends the converted mt-axis signals and motor speed to the adaptive state observation unit and the modulation control unit. The adaptive state observation unit adaptively acquires the operating state and dynamic parameter model of the high-voltage asynchronous motor and sends it to the modulation control unit. The modulation and control unit generates the control drive signal according to the modulation control command and the working state and dynamic parameter model of the high-voltage asynchronous motor; The adaptive state observation unit includes an m-axis observation structure and a t-axis observation structure. Both the m-axis and t-axis observation structures include an ASO observer and a controller. The ASO observer sends the observed data to the controller. The high-voltage motor model in the ASO observer is represented as follows: （1） in, This represents the current along the m-axis in the m-t coordinate system. This represents the current along the t-axis in the mt coordinate system. This represents the voltage along the m-axis in the mt coordinate system. Let represent the voltage along the t-axis in the mt coordinate system; since the m-axis coincides with the rotor flux linkage vector, is used. Indicates the m-axis; This indicates the mutual inductance between the coaxial equivalent windings of the stator and rotor. This represents the self-inductance of the equivalent two-phase stator winding. This represents the self-inductance of the rotor's equivalent two-phase winding; This indicates the winding resistance of the stator; This indicates the winding resistance of the rotor; The leakage flux coefficient of the motor; The rotor electromagnetic time constant; Let dq be the rotational angular velocity of the orthogonal coordinate axes relative to the stator; This refers to the rotational speed of the high-voltage asynchronous motor. use and To represent the uncertainty of the high-voltage motor model, the high-voltage motor model is further expressed as the following nonlinear model: （2） in, ; According to formula (2), define the models of the two subsystems, m-axis and t-axis: （3） （4） Based on formulas (3) and (4), the algorithm model of the ASO observer is obtained as follows: （5） （6） The total disturbance model can be obtained from formulas (5) and (6): （7） in, and Observed by the ASO observer; Defined as: （8） in, The deviation between the ASO observer output and the true value; Indicates taking The symbol; Used for adjustment Gain, This is the error coefficient, used to adjust the magnitude of the error.

2. The high-voltage asynchronous motor control system according to claim 1, characterized in that: The three-phase cascaded power stage structure includes a DC bus and several half-bridge SM sub-modules or several full-bridge SM sub-modules. The DC bus forms a three-phase inverter circuit through several half-bridge SM sub-modules or several full-bridge SM sub-modules. Each phase uses 2N half-bridge SM sub-modules or 2N full-bridge SM sub-modules. The 2N half-bridge SM sub-modules or 2N full-bridge SM sub-modules of each phase form two branches. Each branch is equipped with a reactor and an equivalent resistance. The two branches of each phase are connected to a high-voltage asynchronous motor after merging. Each half-bridge SM sub-module or full-bridge SM sub-module is equipped with a set of power capacitors for energy storage. Each half-bridge SM sub-module or full-bridge SM sub-module is connected to a modulation control unit.

3. A high-voltage asynchronous motor control system according to claim 2, characterized in that: Each phase uses a sinusoidal signal as the basic modulation signal. Within the same phase, each half-bridge SM submodule or full-bridge SM submodule uses two triangular waves as carrier signals. The basic modulation signals between different phases differ by 120 degrees; the basic modulation signals between adjacent half-bridge SM submodules or adjacent full-bridge SM submodules differ by... The two carrier signals of the same half-bridge SM submodule or full-bridge SM submodule are phase-differential. .

4. A high-voltage asynchronous motor control system according to claim 1, characterized in that: The controller is a high-voltage motor controller, and the design method of the high-voltage motor controller includes hysteresis and SVPWM.

5. A high-voltage asynchronous motor control system according to claim 2, characterized in that: The voltage of the half-bridge SM submodule or the full-bridge SM submodule is 1200V~1700V.

6. A high-voltage asynchronous motor control system according to claim 3, characterized in that: The modulation control unit generates the basic modulation signal and the control drive signal according to the modulation control command and the working state and dynamic parameter model of the high-voltage asynchronous motor.

7. A high-voltage asynchronous motor control system according to claim 1, characterized in that: The modulation and control unit is connected to the three-phase cascaded power stage structure via optical fiber.

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