CN106842018B

CN106842018B - Off-line acquisition method and system for three-phase asynchronous motor parameters

Info

Publication number: CN106842018B
Application number: CN201611118070.2A
Authority: CN
Inventors: 王雪迪; 杨扬; 杜继光; 丛培城
Original assignee: CRRC Dalian R&D Co Ltd
Current assignee: CRRC Dalian R&D Co Ltd
Priority date: 2016-12-07
Filing date: 2016-12-07
Publication date: 2023-08-18
Anticipated expiration: 2036-12-07
Also published as: CN106842018A

Abstract

The invention provides an offline acquisition method and system for parameters of a three-phase asynchronous motor. The method comprises the following steps: the controller drives the inverter to apply excitation voltage to any two phases of the three-phase asynchronous motor in different time periods, and collects response currents generated by the three-phase asynchronous motor in different time periods according to the excitation voltage; the controller obtains leakage inductance of the three-phase asynchronous motor according to the excitation voltage, the response current and the first equivalent circuit, and obtains a first time constant of the three-phase asynchronous motor according to the response current and the second equivalent circuit. According to the technical scheme, under the condition that the motor is installed, parameters of the motor can be identified statically, a good initial value can be provided for an online identification algorithm, and therefore safe and reliable starting of the three-phase asynchronous motor is guaranteed, and the convergence speed of the online identification algorithm is increased.

Description

Off-line acquisition method and system for three-phase asynchronous motor parameters

Technical Field

The invention relates to a three-phase asynchronous motor parameter identification technology, in particular to a three-phase asynchronous motor parameter offline acquisition method and system.

Background

In the current three-phase asynchronous motor variable frequency speed regulation system, vector control is considered as an ideal control method, wherein the vector control method is used for respectively controlling exciting current and torque current of an asynchronous motor according to a magnetic field orientation principle, so that the aim of controlling the torque of the asynchronous motor is fulfilled. However, there are still some problems to be solved in the vector control technology, one of which is how to accurately determine internal parameters of the three-phase asynchronous motor, such as stator resistance, rotor resistance, leakage inductance, mutual inductance, and the like, so as to ensure correct orientation of the magnetic field.

Currently, methods for determining internal parameters of a motor include an electromechanical experimental method and an off-line identification method. The electromechanical experimental method is not applicable to the three-phase asynchronous motor which is already installed. The current common offline identification method is that under the condition that the three-phase asynchronous motor is static, the fundamental wave current and the voltage of the three-phase asynchronous motor are calculated respectively through voltage and current excitation injected into the three-phase asynchronous motor and corresponding response and through a Fourier algorithm, so that the internal parameters of the three-phase asynchronous motor are obtained. However, the existing offline parameter identification method by means of the Fourier algorithm is high in computational complexity and time complexity, and high in performance requirement on the controller.

Therefore, how to quickly and accurately obtain the internal parameters of the installed three-phase asynchronous motor becomes a technical problem to be solved by technicians.

Disclosure of Invention

The invention provides an off-line acquisition method and system for parameters of a three-phase asynchronous motor, which are used for solving the problem that the internal parameters of a static three-phase asynchronous motor cannot be acquired rapidly and accurately in the prior art.

In a first aspect, the present invention provides a method for offline acquiring parameters of a three-phase asynchronous motor, including:

the controller drives the inverter to apply excitation voltage to any two phases of the three-phase asynchronous motor in different time periods, and collects response currents generated by the three-phase asynchronous motor in different time periods according to the excitation voltage;

the controller obtains leakage inductance of the three-phase asynchronous motor according to the excitation voltage, the response current and the first equivalent circuit, and obtains a first time constant of the three-phase asynchronous motor according to the response current and the second equivalent circuit;

wherein the first equivalent circuit is gamma-shaped according to a three-phase asynchronous motor ^-1 And the second equivalent circuit is an equivalent circuit obtained by equivalent of a power supply in the first equivalent circuit into a wire.

In a second aspect, the present invention provides an offline acquisition system for parameters of a three-phase asynchronous motor, including: the device comprises a rectifier, an inverter, a controller, a voltage sensor, a current sensor, a direct-current supporting capacitor and a three-phase asynchronous motor;

the output end of the rectifier is electrically connected with the first input end of the voltage sensor, the first end of the direct current supporting capacitor and the first input end of the inverter respectively, the second input end of the voltage sensor is electrically connected with the second end of the direct current supporting capacitor and grounded, the output end of the voltage sensor is electrically connected with the first input end of the controller, the output end of the controller is electrically connected with the second input end of the inverter, the output end of the inverter is electrically connected with the input end of the current sensor, the first output end of the current sensor is electrically connected with the second input end of the controller, and the second output end of the current sensor is electrically connected with the three-phase asynchronous motor;

the controller is used for driving the inverter to apply excitation voltage to any two phases of the three-phase asynchronous motor in different time periods and collecting response currents generated by the three-phase asynchronous motor in different time periods according to the excitation voltage; according to the excitation voltage, the response current and the first equivalent circuit, leakage inductance of the three-phase asynchronous motor is obtained, and according to the response current and the second equivalent circuit, a first time constant of the three-phase asynchronous motor is obtained;

According to the off-line acquisition method for the parameters of the three-phase asynchronous motor, provided by the invention, the controller drives the inverter to apply excitation voltage to any two phases of the three-phase asynchronous motor in different time periods, and collects response currents generated by the three-phase asynchronous motor in different time periods according to the excitation voltage, the response currents and the first equivalent circuit, so that leakage inductance of the three-phase asynchronous motor is obtained, and a first time constant of the three-phase asynchronous motor is obtained according to the response currents and the second equivalent circuit. According to the technical scheme, under the condition that the motor is installed, leakage inductance of the motor can be intelligently identified, a good initial value can be provided for an online identification algorithm, safe and reliable starting of the three-phase asynchronous motor is further ensured, and convergence speed of the online identification algorithm is increased.

Drawings

In order to more clearly illustrate the invention or the technical solutions of the prior art, the following description of the embodiments or the drawings used in the description of the prior art will be given in brief, it being obvious that the drawings in the description below are some embodiments of the invention and that other drawings can be obtained from them without inventive effort for a person skilled in the art.

Fig. 1 is a schematic flow chart of a first embodiment of an offline acquisition method of parameters of a three-phase asynchronous motor provided by the invention;

FIG. 1a is a T-type equivalent circuit diagram of a three-phase asynchronous motor;

fig. 1b is a f-1 type equivalent circuit diagram of a three-phase asynchronous motor;

FIG. 1c is a first equivalent circuit diagram of the three-phase asynchronous motor of the present invention;

FIG. 1d is a second equivalent circuit diagram of the three-phase asynchronous motor of the present invention;

fig. 2 is a schematic flow chart of a second embodiment of an offline acquisition method of parameters of a three-phase asynchronous motor provided by the invention;

FIG. 2a is a third equivalent circuit diagram of the three-phase asynchronous motor of the present invention;

fig. 2b is a fourth equivalent circuit diagram of the three-phase asynchronous motor of the present invention;

FIG. 3 is a schematic flow chart of a third embodiment of an offline identification method for parameters of a three-phase asynchronous motor according to the present invention;

FIG. 3a is a schematic diagram of excitation voltage and response current of a three-phase asynchronous motor;

fig. 4 is a schematic flow chart of a fourth embodiment of an offline identification method for parameters of a three-phase asynchronous motor according to the present invention;

FIG. 4a is a schematic diagram of excitation current and response voltage of a three-phase asynchronous motor;

fig. 5 is a schematic flow chart of a fifth embodiment of an offline identification method for parameters of a three-phase asynchronous motor according to the present invention;

fig. 6 is a flowchart of a sixth embodiment of an offline identification method for parameters of a three-phase asynchronous motor according to the present invention;

fig. 7 is a schematic structural diagram of an embodiment of an offline identification system for parameters of a three-phase asynchronous motor according to the present invention.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the present invention more apparent, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

The off-line acquisition method of the three-phase asynchronous motor parameters is suitable for an off-line acquisition system of the three-phase asynchronous motor parameters, and is used for solving the problem that the internal parameters of the static three-phase asynchronous motor cannot be simply, conveniently, quickly and accurately obtained in the prior art.

It should be noted that the terms "first," "second," and "second" in this example are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. The motors referred to in this embodiment are all three-phase asynchronous motors.

Fig. 1a is a T-type equivalent circuit diagram of a three-phase asynchronous motor. As shown in fig. 1a, a stator resistance Rs of the three-phase asynchronous motor is connected in series with a stator leakage inductance lsσ of the three-phase asynchronous motor, a rotor leakage inductance Lr σ of the three-phase asynchronous motor and a rotor resistance Rr of the three-phase asynchronous motor, and a mutual inductance Lm of the three-phase asynchronous motor is connected in parallel with the rotor leakage inductance Lr σ of the three-phase asynchronous motor and the rotor resistance Rr of the three-phase asynchronous motor.

Fig. 1b shows f of a three-phase asynchronous motor ^-1 And a model equivalent circuit diagram. On the basis of the T-type equivalent circuit of the three-phase asynchronous motor shown in the figure 1a, when the three-phase asynchronous motor is stationary, as shown in the figure 1b, the gamma of the three-phase asynchronous motor is displayed ^-1 Stator resistance Rs and equivalent leakage inductance L of three-phase asynchronous motor in equivalent circuit diagram _σ ' equivalent leakage inductance L _σ ' is the R ^-1 Leakage inductance of equivalent circuit) and equivalent resistance Rrref of the rotor (equivalent resistance Rrref of the rotor is r ^-1 Rotor equivalent resistance of the equivalent circuit) are connected in series, and the mutual inductance Lm of the three-phase asynchronous motor is connected in parallel with the equivalent resistance Rrref of the rotor. The leakage inductance lσ of the three-phase asynchronous motor is equal to the sum of the stator leakage inductance lsσ and the rotor leakage inductance Lr σ of the three-phase asynchronous motor in fig. 1a, i.e. lσ=lsσ+lr σ.

The technical proposal of the invention is that the three-phase asynchronous motor shown in the figure 1b is a gamma-ray ^-1 The type equivalent circuit is developed on the basis of the model equivalent circuit.

Fig. 1 is a schematic flow chart of an embodiment of an off-line acquisition method of parameters of a three-phase asynchronous motor, which relates to a specific process of determining leakage inductance and a first time constant of the motor by driving an inverter to apply excitation voltage to any two phases of the motor by a controller. As shown in fig. 1, the method of the present embodiment may include:

s101, driving an inverter to apply excitation voltage to any two phases of the three-phase asynchronous motor in different time periods by the controller, and collecting response currents generated by the three-phase asynchronous motor in different time periods according to the excitation voltage.

It should be noted that, the execution body of the embodiment is an offline acquisition system of parameters of a three-phase asynchronous motor, and specifically is a controller in the offline acquisition system of parameters of the three-phase asynchronous motor.

In this embodiment, different excitation voltages are applied to any two phases of the motor in different time periods, and the excitation voltages are obtained by calculation according to the voltage on the direct current bus collected by the direct current voltage sensor and a duty ratio instruction sent by the controller.

Specifically, the controller drives the inverter to apply different excitation voltages to any two phases (such as an A phase and a B phase) of the motor in different time periods according to actual needs, and collects response currents generated by the motor in different time periods according to the excitation voltages.

Alternatively, the controller may collect the response current generated by either phase a or phase B, and use the response current as the response current of the motor.

In the present embodiment, the magnitude and direction of the excitation voltage applied to any two phases of the motor may be determined according to the specific situation, and the present embodiment is not limited thereto.

S102, the controller obtains leakage inductance of the three-phase asynchronous motor according to the excitation voltage, the response current and the first equivalent circuit, and obtains a first time constant of the three-phase asynchronous motor according to the response current and the second equivalent circuit.

Specifically, in the present embodiment, the f shown in FIG. 1b is shown above ^-1 Based on the equivalent circuit, the controller drives the inverter to apply excitation voltage to any two phases of the three-phase asynchronous motor. At this time, because the exciting voltage frequency is higher, the mutual inductance resistance of the three-phase asynchronous motor is larger, and the branch circuit can be equivalently broken. At this time, the first equivalent current diagram of the three-phase asynchronous motor is shown in FIG. 1c, and the three-phase asynchronous motor is composed of a stator resistor Rs and an equivalent leakage inductance L _σ ' and the equivalent resistance Rrref of the rotor. That is, when excitation voltage is applied to any two phases of the three-phase asynchronous motor, the first equivalent circuit of the three-phase asynchronous motor is equivalent to the gamma-type asynchronous motor ^-1 And the equivalent circuit is formed by omitting a mutual inductance Lm branch of the three-phase asynchronous motor in the equivalent circuit.

In the present embodiment, when the excitation voltage applied to any two phases of the three-phase asynchronous motor causes the first response of the three-phase asynchronous motorAnd after the current reaches a preset value, the controller controls the inverter to stop applying exciting voltage to the three-phase asynchronous motor. At this time, due to the existence of leakage inductance, the first equivalent circuit shown in fig. 1c enters a zero input response stage, and then a second equivalent circuit of the three-phase asynchronous motor is formed. The second equivalent circuit of the three-phase asynchronous motor is shown in fig. 1d, and is an equivalent circuit obtained by equivalent of the power supply in the first equivalent circuit into wires, namely, the stator resistor Rs and the equivalent leakage inductance L of the three-phase asynchronous motor _σ ' and the equivalent resistance Rrref of the rotor form a loop.

According to the technical scheme of the embodiment, the controller can calculate leakage inductance L of the three-phase asynchronous motor according to the excitation voltage, the response current and the first equivalent circuit _σ '. Specifically, according to the excitation voltage and the response current of the corresponding time period of the first equivalent circuit, computing the gamma by combining the first equivalent circuit ^-1 Leakage inductance of equivalent circuit, i.e. equivalent leakage inductance L _σ ' according to the equivalent leakage inductance L _σ ' leakage inductance L of motor _σ To obtain leakage inductance L of the motor _σ (see description of the embodiments below for specific methods). And obtaining a first time constant of the three-phase asynchronous motor according to the response current and the second equivalent circuit. Specifically, according to the response current of the corresponding time period of the second equivalent circuit, the first time constant of the motor is calculated by combining the second equivalent circuit.

For example, a positive first excitation voltage is applied to the a phase and the B phase of the motor in a first period, the first response current collected at this time increases linearly, the excitation voltage is stopped to be applied to the motor in a second period, the first response current collected at this time decreases progressively, a negative second excitation voltage is applied to the a phase and the B phase of the motor in a third period, the first response current collected at this time decreases linearly, and the excitation voltage is stopped to be applied to the motor in a fourth period. The controller of the embodiment calculates leakage inductance of the motor according to the second excitation voltage and the response current corresponding to the third time period and the first equivalent circuit corresponding to the third time period. The controller calculates a first time constant of the motor according to the response current corresponding to the second time period and the second equivalent circuit corresponding to the second time period.

According to the off-line acquisition method for the parameters of the three-phase asynchronous motor, the controller drives the inverter to apply excitation voltages to any two phases of the three-phase asynchronous motor in different time periods, and collects response currents generated by the three-phase asynchronous motor in different time periods according to the excitation voltages, the controller obtains leakage inductance of the three-phase asynchronous motor according to the excitation voltages, the response currents and the first equivalent circuit, and obtains a first time constant of the three-phase asynchronous motor according to the response currents and the second equivalent circuit. According to the technical scheme, under the condition that the motor is installed, leakage inductance of the motor can be intelligently identified, a good initial value can be provided for an online identification algorithm, safe and reliable starting of the three-phase asynchronous motor is further ensured, and convergence speed of the online identification algorithm is increased.

Fig. 2 is a schematic flow chart of a second embodiment of an offline acquisition method of parameters of a three-phase asynchronous motor provided by the invention. On the basis of the above embodiment, the present embodiment relates to a specific process of determining the stator resistance Rs and the second time constant Ts of the three-phase asynchronous motor by applying excitation current to any two phases of the three-phase asynchronous motor. As shown in fig. 2, the method of the present embodiment may include:

And S201, the controller drives the inverter to apply exciting currents to any two phases of the three-phase asynchronous motor in different time periods, and calculates response voltages generated by the three-phase asynchronous motor in different time periods according to the exciting currents.

Specifically, the controller drives the inverter to apply different excitation currents to any two phases (such as an A phase and a B phase) of the motor in different time periods according to actual needs, and calculates response voltages of the motor generated according to the excitation currents in different time periods. Wherein the excitation current is a direct current.

Alternatively, the controller may collect the response voltage generated by either phase a or phase B, and use the response voltage as the response voltage of the motor.

In this embodiment, the magnitude and direction of the excitation current applied to any two phases of the motor may be determined according to the specific situation, and this embodiment is not limited thereto.

And S202, the controller obtains the stator resistance of the three-phase asynchronous motor according to the excitation current, the response voltage and the third equivalent circuit, and obtains the second time constant of the three-phase asynchronous motor according to the excitation current and the fourth equivalent circuit.

Wherein the third equivalent circuit is to convert the gamma ^-1 The leakage inductance and the mutual inductance in the equivalent circuit are equivalent to be the equivalent circuit obtained by conducting wires, and the fourth equivalent circuit is obtained by making the gamma-shaped ^-1 And the leakage inductance and the power supply in the equivalent circuit are equivalent to be an equivalent circuit obtained by conducting wires.

Specifically, in this embodiment, on the basis of the f-1 type equivalent circuit shown in fig. 1b, the controller drives the inverter to apply exciting current to any two phases of the three-phase asynchronous motor, and at this time, due to the characteristic that the direct current of the inductor isolates alternating current, the inductance of the three-phase asynchronous motor (i.e. the equivalent leakage inductance L of the motor _σ ' mutual inductance with the motor) is approximately one wire, a third equivalent circuit of the three-phase asynchronous motor can be obtained. The third equivalent circuit of the three-phase asynchronous motor at this time is shown in fig. 2a and consists of the stator resistor Rs of the three-phase asynchronous motor. In this embodiment, when excitation current is applied to any two phases of the three-phase asynchronous motor, the third equivalent circuit of the three-phase asynchronous motor is equivalent to a f-type asynchronous motor ^-1 The inductance in the equivalent circuit is equivalent to an equivalent circuit obtained by a wire.

In this example, f will be ^-1 Equivalent leakage inductance L in equivalent circuit _σ The' and the power supply are approximately formed into one wire, and a fourth equivalent circuit shown in fig. 2b is obtained, wherein the fourth equivalent circuit consists of a stator resistance Rs of the three-phase asynchronous motor, an equivalent resistance Rrref of the rotor and a mutual inductance Lm, the mutual inductance Lm of the three-phase asynchronous motor is connected with the equivalent resistance Rrref of the rotor in parallel, and the stator resistance Rs and the equivalent resistance Rrref of the rotor are connected in series.

According to the technical scheme of the embodiment, the controller can calculate the stator resistance Rs of the three-phase asynchronous motor according to the exciting current, the response voltage and the third equivalent circuit. Specifically, according to the excitation current and the response voltage of the time period corresponding to the third equivalent circuit, the stator resistance Rs of the motor is calculated by combining the third equivalent circuit. And obtaining a second time constant of the three-phase asynchronous motor according to the excitation current and the fourth equivalent circuit. Specifically, the second time constant of the motor is calculated according to the excitation current of the time period corresponding to the fourth equivalent circuit and the fourth equivalent circuit.

For example, a forward first excitation current is applied to the A phase and the B phase of the motor in a first period of time, and after the first excitation current stabilizes, a second response voltage at the moment is calculated. And sequentially applying a second forward exciting current to the A phase and the B phase of the motor in a second time period, and calculating a fourth response voltage at the moment after the second exciting current is stable. And applying negative third exciting currents to the A phase and the B phase of the motor in a third time period, and applying fourth exciting currents to the A phase and the B phase of the motor in a fourth time period when the third exciting currents meet a fifth preset value and when the fourth exciting currents meet a sixth preset value. The controller of the embodiment calculates and obtains the stator resistance Rs of the motor according to the stable first excitation current value and the first response voltage value corresponding to the first time period, the stable second excitation current value and the first response voltage value corresponding to the second time period, and the third equivalent circuit. And calculating to obtain a second time constant of the motor according to a fourth exciting current and a fourth equivalent circuit corresponding to the fourth time period.

The specific calculation formula of the stator resistance Rs of the three-phase asynchronous motor is not limited in this embodiment, so long as the specific calculation formula is obtained according to the excitation current, the response voltage and the third equivalent circuit of the three-phase asynchronous motor.

The specific calculation formula of the second time constant Ts of the three-phase asynchronous motor is not limited in this embodiment, so long as the specific calculation formula is obtained according to the excitation current and the fourth equivalent circuit.

According to the method, the controller drives the inverter to apply different excitation currents to any two phases of the three-phase asynchronous motor in different time periods, calculates response voltages generated by any two phases of the three-phase asynchronous motor in different time periods according to the different excitation currents, and calculates and obtains the stator resistance Rs and the second time constant Ts of the three-phase asynchronous motor by combining a third equivalent circuit and a fourth equivalent circuit.

And S203, the controller obtains the mutual inductance and the rotor resistance of the three-phase asynchronous motor according to the first time constant, the second time constant, the leakage inductance and the stator resistance of the three-phase asynchronous motor.

Specifically, the controller obtains the first time constant Tk, the second time constant Ts, and the leakage inductance lσ (specifically, the equivalent leakage inductance L _σ ') and stator resistance Rs, and the mutual inductance Lm and rotor resistance Rr can be obtained in combination with the prior art.

According to the off-line acquisition method for the parameters of the three-phase asynchronous motor, provided by the invention, the controller drives the inverter to apply excitation current to any two phases of the three-phase asynchronous motor in different time periods, and calculates response voltages generated by the three-phase asynchronous motor in different time periods according to the excitation current. The controller obtains the stator resistance of the three-phase asynchronous motor according to the excitation current, the response voltage and the third equivalent circuit, and obtains the second time constant of the three-phase asynchronous motor according to the excitation current and the fourth equivalent circuit. And finally, the controller obtains the mutual inductance and the rotor resistance of the three-phase asynchronous motor according to the first time constant, the second time constant, the leakage inductance and the stator resistance of the three-phase asynchronous motor. According to the method, under the condition of motor installation, leakage inductance Lsigma, stator resistance Rs, mutual inductance Lm and rotor resistance Rr of the motor can be obtained, so that a good initial value is provided for an online identification algorithm, safe and reliable starting of the three-phase asynchronous motor is further ensured, and the convergence speed of the online identification algorithm is accelerated.

Fig. 3 is a schematic flow chart of a third embodiment of an offline identification method for parameters of a three-phase asynchronous motor. Fig. 3a is a schematic diagram of the excitation voltage and the response current of a three-phase asynchronous motor. On the basis of the above embodiment, the present embodiment relates to a specific process that the controller obtains the first time constant of the three-phase asynchronous motor according to the response current and the second equivalent circuit. As shown in fig. 3, the step S102 may specifically include:

s301, at the time t0 to ti, the controller drives the inverter to apply a first excitation voltage to any two phases of the three-phase asynchronous motor, and obtains a first response current corresponding to the first equivalent circuit in the time period t0 to ti, wherein i is any positive number.

Specifically, referring to fig. 3a, at time t0 to ti, a first excitation voltage is applied to any two phases of the three-phase asynchronous motor, at this time, the equivalent circuit of the three-phase asynchronous motor is the first equivalent circuit shown in fig. 1c, the first excitation voltage and the first response current generated by the three-phase asynchronous motor are as shown in fig. 3a, and when a forward first excitation voltage is applied to any two phases of the three-phase asynchronous motor, the first response current of the three-phase asynchronous motor rises linearly with increasing of the time of applying the first excitation voltage.

Alternatively, in this embodiment, the magnitude of the first excitation voltage applied by the controller to drive the inverter to any two phases of the three-phase asynchronous motor may be set according to actual needs, and the magnitude and direction of the first excitation voltage are not limited in this embodiment.

And S302, when the first response current corresponding to the ti moment is equal to a first preset current value, the controller controls the inverter to stop applying a first excitation voltage to the three-phase asynchronous motor, and a second response current corresponding to the second equivalent circuit in a ti-ti+1 time period is obtained.

Optionally, the magnitude of the first preset current value is not limited in this embodiment, and may be specifically set according to actual needs. Preferably, the first preset current value of the embodiment may be a forward current limit value of the three-phase asynchronous motor.

And S303, the controller obtains a first time constant of the three-phase asynchronous motor according to the integral of the second response current in the time period of ti to ti+1, the difference value of the second response current in the time period of ti to ti+1 and the second equivalent circuit.

Specifically, as shown in fig. 3a, at time ti, the first response current reaches a first preset current value, the controller controls the inverter to stop applying the first excitation voltage to the three-phase asynchronous motor, and at this time, the first equivalent circuit of the three-phase asynchronous motor enters a zero-input effect stage, and the equivalent circuit diagram of the three-phase asynchronous motor is a second equivalent circuit diagram shown in fig. 1 d. As shown in fig. 3a, the second response current on any two phases of the three-phase asynchronous motor gradually decreases, and the second response current decreases to a certain preset value (for example, 1/2 of the first preset current value) at time ti+1. The controller collects second response currents corresponding to the second equivalent circuits in the time periods of ti to ti+1.

The controller calculates a first time constant Tk of the three-phase asynchronous motor according to the integral of the second response current in the time period of ti to ti+1, the difference value of the second response current in the time period of ti to ti+1 and the second equivalent circuit.

Alternatively, the controller may be in accordance with the formulaTo calculate a first time constant Tk of the three-phase asynchronous motor.

Wherein, rk=Rs+Rrref, rs is the stator resistance of the three-phase asynchronous motor, rrref is the gamma ^-1 Rotor equivalent resistance of the equivalent circuit, wherein Tk is a first time constant, L, of the three-phase asynchronous motor _σ ' is said R ^-1 And leakage inductance of the type equivalent circuit, wherein the iInt is the integral of the second response current in the time period from ti to ti+1, and the iDif is the difference value of the second response current in the time period from ti to ti+1.

According to the off-line acquisition method of the three-phase asynchronous motor parameters, the controller drives the inverter to apply the first excitation voltage on any two phases of the three-phase asynchronous motor in the period from t0 to ti, the first response current corresponding to the first equivalent circuit in the period is acquired, when the first response current reaches a first preset current value, the application of the first excitation voltage to the three-phase asynchronous motor is stopped, at the moment, the first equivalent circuit enters a zero input effect stage, the second response current of the motor is gradually reduced, the controller acquires the second response current of the three-phase asynchronous motor in the period from ti to ti+1, and the first time constant Tk of the three-phase asynchronous motor is calculated and obtained according to the integral of the second response current, the conversion value of the second response current and the second equivalent circuit in the period from ti to ti+1 and by combining the formula (1).

Fig. 4 is a flow chart of a fourth embodiment of the method for identifying parameters of a three-phase asynchronous motor offline, and fig. 4a is a schematic diagram of excitation current and response voltage of the three-phase asynchronous motor. On the basis of the above embodiment, the present embodiment relates to a specific process in which the controller obtains the stator resistance of the three-phase asynchronous motor according to the excitation current, the response voltage, and the third equivalent circuit. As shown in fig. 4, the step S202 may specifically include:

s401, at the time t0 to tj, the controller drives the inverter to gradually and progressively apply a first excitation current to any two phases of the three-phase asynchronous motor from zero, and calculates a first response voltage corresponding to a time period t0 to tj, wherein j is any positive number.

And S402, when the first excitation current corresponding to the tj-tj+1 time period is stabilized at a third preset current value, the controller calculates a second response voltage corresponding to the third equivalent circuit in the tj-tj+1 time period.

As shown in fig. 4a, at the time points t0 to tj, the controller drives the inverter to gradually and progressively apply the first excitation current to any two phases of the three-phase asynchronous motor from zero. Due to the presence of the inductance, the first response voltage rises linearly with increasing first excitation current as the first excitation current increases gradually.

When tj to tj+1 time periods, the first excitation current is stabilized at a third preset current value i1, and the controller calculates a second response voltage U1 corresponding to the time periods of tj to tj+1. As shown in fig. 4a, when the first excitation current is stabilized at i1, the second response voltage is also stabilized at U1, and the equivalent circuit of the motor is the third equivalent circuit diagram shown in fig. 2 a.

Optionally, in this embodiment, the magnitude of the first excitation current applied by the controller to drive the inverter to any two phases of the three-phase asynchronous motor may be set according to actual needs, and in this embodiment, the magnitude and the positive and negative of the first excitation current are not limited.

S403, at the time tj+1 to tj+2, the controller drives the inverter to apply a second excitation current to any two phases of the three-phase asynchronous motor gradually and progressively from a first excitation current corresponding to the time tj+1, and obtains a third response voltage corresponding to the time period tj+1 to tj+2.

And S404, when the second excitation current corresponding to the time period from tj+2 to tj+3 is stabilized at a fourth preset current value, the controller calculates a fourth response voltage corresponding to the third equivalent circuit in the time period from tj+2 to tj+3.

Specifically, as shown in fig. 4a, when the first excitation current is stable for a period of time at the value of i1, and then at the time tj+1 to tj+2, the controller drives the inverter to gradually and progressively apply a second excitation current (the direction of the second excitation current is the same as that of the first excitation current) to any two phases of the three-phase asynchronous motor from the first excitation current i1 corresponding to the time tj+1, and obtain a third response voltage corresponding to the time period tj+1 to tj+2.

In the time period tj+2 to tj+3, the first excitation current is stabilized at a fourth preset current value i2, and the controller calculates a fourth response voltage U2 corresponding to the time period tj+2 to tj+3. As shown in fig. 4a, when the first excitation current is stabilized at i2, the fourth response voltage is also stabilized at U2, and the equivalent circuit corresponding to the three-phase asynchronous motor is the third equivalent circuit shown in fig. 2 a.

Optionally, the third preset current value and the fourth preset current value in this embodiment may be set according to actual needs. Preferably, the fourth preset current value in this embodiment may be a negative current limit value of the three-phase asynchronous motor, and the third preset current value may be 1/2 of the fourth preset current value.

It should be noted that, as shown in fig. 4a, in the time periods from t0 to tj and from tj+1 to tj+2, the controller drives the inverter to apply forward exciting currents to any two phases of the three-phase asynchronous motor, and the corresponding first exciting current, first response voltage and third response voltage are increased in forward directions. Alternatively, negative exciting currents can be applied to any two phases of the three-phase asynchronous motor in the time periods of t0 to tj and tj+1 to tj+2, and the corresponding first exciting current, first response voltage and third response voltage are in negative increasing.

And S405, the controller obtains the stator resistance of the three-phase asynchronous motor according to the first exciting current and the second response voltage of the tj to tj+1 time period, the second exciting current and the fourth response voltage of the tj+2 to tj+3 time period and the third equivalent circuit.

Specifically, the controller obtains the stator resistance Rs of the three-phase asynchronous motor according to the first excitation current i1 and the second response voltage U1 corresponding to the tj to tj+1 time periods, the first excitation current i2 and the fourth response voltage U2 corresponding to the tj+2 to tj+3 time periods, and the third equivalent circuit.

Alternatively, the controller may be in accordance with the formulaAnd calculating the stator resistance Rs of the three-phase asynchronous motor.

The Rs is a stator resistance of the three-phase asynchronous motor, the I1 and the U1 are a first excitation current and a first response voltage of the three-phase asynchronous motor in the tj to tj+1 time period, and the I2 and the U2 are a second excitation current and a fourth response voltage of the three-phase asynchronous motor in the tj+2 to tj+3 time period.

According to the off-line acquisition method of the three-phase asynchronous motor parameters, the controller drives the inverter to gradually and progressively apply the first excitation current from zero to any two phases of the three-phase asynchronous motor in the time period from t0 to tj, the first response voltage corresponding to the third equivalent circuit in the time period is calculated, and when the first excitation current is stabilized at a third preset current value in the time period from tj to tj+1, the first excitation current i1 and the second response voltage U1 corresponding to the time period from tj to tj+1 are acquired. At the time of tj+1 to tj+2, the controller drives the inverter to gradually and progressively apply a second excitation current to any two phases of the three-phase asynchronous motor from a first excitation current corresponding to the time of tj+1, and when the first excitation current in the time period of tj+2 to tj+3 is stabilized at a fourth preset current value, the controller calculates a first response voltage U2 corresponding to the time period of tj+2 to tj+3. And calculating to obtain the stator resistance Rs of the three-phase asynchronous motor according to i1 and U1, i2 and U2 and the formula (2).

Fig. 5 is a schematic flow chart of a fifth embodiment of an offline identification method for parameters of a three-phase asynchronous motor. On the basis of the above embodiment, the present embodiment relates to a specific process that the controller obtains the second time constant of the three-phase asynchronous motor according to the excitation current and the fourth equivalent circuit. As shown in fig. 5, the step S202 may specifically include:

and S501, at the time tj+3 to tj+4, the controller drives the inverter to gradually and progressively apply a third exciting current to any two phases of the three-phase asynchronous motor, wherein the third exciting current is a current which gradually and progressively changes from the second exciting current corresponding to the time tj+3 to the opposite direction of the second exciting current.

With continued reference to fig. 4a described above, in this embodiment, at times tj+3 to tj+4, the controller drives the inverter to apply a stepped third excitation current to any two phases of the three-phase asynchronous motor, which may be stepped from positive i2 to negative (e.g., 75% of i2 to negative).

And S502, when the third excitation current corresponding to the tj+4 moment is equal to a fifth preset current value, the controller drives the inverter to gradually and progressively apply a fourth excitation current to any two phases of the three-phase asynchronous motor from the third excitation current corresponding to the tj+4 moment.

Specifically, at time tj+4, when the third excitation current decreases to a fifth preset current (i 2 of 75% negative direction, for example), since the mutual inductance value is far greater than the leakage inductance value, f ^-1 The leakage inductance in the equivalent circuit basically disappears and is equivalent to the conducting wire, but the mutual inductance of the motor still acts, and at the moment, the fourth equivalent circuit is that the gamma is formed by ^-1 And the leakage inductance and the power supply in the equivalent circuit are equivalent to an equivalent circuit obtained by conducting wires.

The controller drives the inverter to gradually and progressively apply the third excitation current and the fourth excitation current to any two phases of the three-phase asynchronous motor from the time tj+4. The direction of the fourth excitation current is negative.

And S503, when the fourth excitation current corresponding to the tj+5 moment is equal to a sixth preset current value, the controller controls the inverter to stop applying the fourth excitation current to the three-phase asynchronous motor.

Specifically, as shown in fig. 4a, at time tj+5, the first excitation current is equal to a sixth preset current value (e.g., equal to negative i 2). The controller controls the inverter to stop applying voltage to the motor, and the whole test process is finished. As shown in fig. 4a, the controller obtains an integral of the fourth excitation current, the difference of the fourth excitation current, over the period tj+4 to tj+5.

And S504, the controller obtains a second time constant of the three-phase asynchronous motor according to the integral of the fourth exciting current, the difference value of the fourth exciting current and the fourth equivalent circuit in the time period from tj+4 to tj+5.

In the present embodiment, the controller calculates the second time constant of the three-phase asynchronous motor from the integral of the fourth excitation current, the difference of the fourth excitation current, and the fourth equivalent circuit in the tj+4 to tj+5 time periods.

Alternatively, the controller may be in accordance with the formulaAnd calculating a second time constant of the three-phase asynchronous motor.

The Ts is a second time constant of the three-phase asynchronous motor, lm is a mutual inductance of the three-phase asynchronous motor, iInt is an integral of a fourth excitation current in a time period from tj+4 to tj+5, and iDif is a difference value of the fourth excitation current in a time period from tj+4 to tj+5.

According to the offline acquisition method of the three-phase asynchronous motor parameters, the controller drives the inverter to gradually and progressively apply the third excitation current to any two phases of the motor at the time tj+3 to tj+4, when the third excitation current corresponding to the time tj+4 is equal to a fifth preset current value, the controller drives the inverter to gradually and progressively apply the fourth excitation current to any two phases of the motor from the third excitation current corresponding to the time tj+4, when the fourth excitation current corresponding to the time ti+5 is equal to a sixth preset current value, the controller controls the inverter to stop applying the fourth excitation current to the three-phase asynchronous motor, and the controller obtains the second time constant of the three-phase asynchronous motor according to the integral of the fourth excitation current, the difference value of the fourth excitation current and the fourth equivalent circuit in the time period of tj+4 to tj+5 and the formula.

Fig. 6 is a flowchart of a sixth embodiment of an offline identification method for parameters of a three-phase asynchronous motor according to the present invention. On the basis of the above embodiment, the present embodiment relates to a specific process in which the controller obtains the leakage inductance lσ of the three-phase asynchronous motor according to the excitation voltage, the response current, and the first equivalent circuit. As shown in fig. 6, the step S102 may specifically include:

s601, at the time of ti+1 to ti+2, the controller drives the inverter to apply a second excitation voltage to any two phases of the three-phase asynchronous motor, and obtains a third response current corresponding to the first equivalent circuit in the time period of ti+1 to ti+2.

With continued reference to fig. 3a. Specifically, in the time period ti+1 to ti+2, the controller drives the inverter to apply a second excitation voltage to any two phases of the three-phase asynchronous motor (optionally, the direction of the second excitation voltage is opposite to the direction of the first excitation voltage), and the equivalent circuit of the three-phase asynchronous motor is the first equivalent circuit shown in fig. 1 c. As shown in fig. 3a, the third response current decreases linearly with increasing application time of the second excitation voltage in the period ti+1 to ti+2. The controller collects third response currents corresponding to the first equivalent circuits in the time periods of ti+1 to ti+2.

It should be noted that fig. 3a shows that negative voltages are applied to any two phases of the three-phase asynchronous motor in the time periods ti+1 to ti+2, and the corresponding third response currents are linearly increased in negative directions. Alternatively, a forward voltage can be applied to any two phases of the three-phase asynchronous motor in the time period of ti+1 to ti+2, and the corresponding third response current increases in a forward direction. The magnitude and the positive and negative of the second excitation voltage are not limited in this embodiment, and are specifically set according to actual needs.

And S602, when the third response current corresponding to the ti+2 moment is equal to a second preset current value, the controller controls the inverter to stop applying a second excitation voltage to the three-phase asynchronous motor.

Optionally, the magnitude of the second preset current value is not limited in this embodiment, and may be specifically set according to actual needs. Preferably, the second preset current value of the embodiment may be a negative current limit value of the three-phase asynchronous motor.

And S603, the controller obtains leakage inductance of the three-phase asynchronous motor according to the integral of the second excitation voltage, the difference value of the third response current and the first equivalent circuit in the time period of ti+1 to ti+2.

Specifically, at the time ti+2, the third response current reaches a second preset current value, at this time, the controller controls the inverter to stop applying the second excitation voltage to the three-phase asynchronous motor, and collects the third response current in the time period ti+1 to ti+2.

The controller calculates and obtains leakage inductance Lsigma of the three-phase asynchronous motor according to the integral of the second excitation voltage, the difference value of the third response current and the first equivalent circuit in the time period of ti+1 to ti+2.

Alternatively, the controller may be in accordance with the formulaCalculating said f ^-1 Leakage inductance L of equivalent circuit _σ ' further according to the formula->And formula->And calculating to obtain leakage inductance Lsigma of the three-phase asynchronous motor.

The uInt is an integral of the second excitation voltage in the time period from ti+1 to ti+2, the iDif is a difference value of the third response current in the time period from ti+1 to ti+2, lm is a mutual inductance of the three-phase asynchronous motor, lr sigma is a rotor leakage inductance of the three-phase asynchronous motor, and Ls sigma is a stator leakage inductance lssigma of the three-phase asynchronous motor.

Specifically, rk is obtained according to the above formula (1) and the above formula (4), wherein rk=rs+rref, and the mutual inductance L of the motor can be obtained by combining the above formulas (2) and (3) _m Mutual inductance L of motor _m Substituting the leakage inductance Lsigma of the motor into the formula (5) and combining the formula (6).

Further, the parameters of the motor obtained by calculation are substituted into a formulaIn (3) obtaining the rotor resistance R of the motor _r 。

According to the technical scheme, under the condition that the motor is installed, the leakage inductance Lsigma, the stator resistance Rs, the first time constant Tk, the second time constant Ts, the stator leakage inductance Lsigma, the rotor leakage inductance Lr sigma, the mutual inductance Lm of the three-phase asynchronous motor and other three-phase asynchronous motor internal parameters can be obtained according to the method, and a good initial value can be provided for an online identification algorithm, so that safe and reliable starting of the three-phase asynchronous motor is ensured, and the convergence rate of the online identification algorithm is accelerated.

Fig. 7 is a schematic structural diagram of an embodiment of an offline acquisition system for parameters of a three-phase asynchronous motor according to the present invention, as shown in fig. 7, the system of the present embodiment may include: the three-phase asynchronous motor comprises a rectifier 1, an inverter 3, a controller 5, a voltage sensor 7, a current sensor 6, a direct-current supporting capacitor 2 and a three-phase asynchronous motor 4;

the output end 12 of the rectifier 1 is electrically connected with the first input end 71 of the voltage sensor 7, the first end 21 of the direct current supporting capacitor 2 and the first input end 31 of the inverter 3 respectively, the second input end 72 of the voltage sensor 7 is electrically connected with the second end 22 of the direct current supporting capacitor 2 and grounded, the output end 73 of the voltage sensor 7 is electrically connected with the first input end 51 of the controller 5, the output end 53 of the controller 5 is electrically connected with the second input end 32 of the inverter 3, the output end 33 of the inverter 3 is electrically connected with the input end 61 of the current sensor 6, the first output end 62 of the current sensor 6 is electrically connected with the second input end 52 of the controller 5, and the second output end 63 of the current sensor 6 is electrically connected with the three-phase asynchronous motor 4;

the controller 5 is used for driving the inverter 3 to apply excitation voltages to any two phases of the three-phase asynchronous motor 4 in different time periods and collecting response currents generated by the three-phase asynchronous motor 4 according to the excitation voltages in different time periods; and according to the excitation voltage, the response current and the first equivalent circuit, leakage inductance of the three-phase asynchronous motor 4 is obtained, and according to the response current and the second equivalent circuit, a first time constant of the three-phase asynchronous motor 4 is obtained.

Wherein the first equivalent circuit is gamma-shaped according to the three-phase asynchronous motor 4 ^-1 And ignoring the equivalent circuit obtained by mutual inductance of the three-phase asynchronous motor 4, wherein the second equivalent circuit is an equivalent circuit obtained by equivalent of a power supply in the first equivalent circuit into a wire.

Specifically, as shown in fig. 7, the electric drive system of the three-phase asynchronous motor 4 of the present invention includes a rectifier 1, an inverter 3, a controller 5, a voltage sensor 7, a current sensor 6, a direct-current support capacitor 2, and the three-phase asynchronous motor 4. The output end 12 of the rectifier 1 is respectively electrically connected with the first input end 71 of the voltage sensor 7, the first end 21 of the direct current supporting capacitor 2 and the first input end 31 of the inverter 3, the second input end 72 of the voltage sensor 7 is electrically connected with the second end 22 of the direct current supporting capacitor 2 and grounded, the output end 73 of the voltage sensor 7 is electrically connected with the first input end 51 of the controller 5, the output end 53 of the controller 5 is electrically connected with the second input end 32 of the inverter 3, the output end 33 of the inverter 3 is electrically connected with the input end 61 of the current sensor 6, the first output end 62 of the current sensor 6 is electrically connected with the second input end 52 of the controller 5, and the second output end 63 of the current sensor 6 is electrically connected with the three-phase asynchronous motor 4; wherein the second terminal 22 of the dc supporting capacitor 2 is grounded. Wherein the arrow direction in fig. 7 indicates the flow direction of the electrical signal.

In this embodiment, after the three-phase asynchronous motor 4 is installed, the alternating current is rectified into direct current by the rectifier 1, the direct current supporting capacitor 2 enables the direct current voltage input into the inverter 3 to be more stable, the voltage sensor 7 is used for detecting the direct current voltage value in real time, the controller 5 is used for driving the inverter 3 to invert the direct current into alternating current, so that the alternating current supplies power to the three-phase asynchronous motor 4, and the current sensor 6 is used for detecting the input current of the three-phase asynchronous motor 4 in real time.

The offline acquisition system for parameters of the three-phase asynchronous motor provided by the invention is used for realizing the technical scheme of the embodiment of the method, and the specific implementation process and principle of the offline acquisition system refer to the description of the embodiment of the method and are not repeated herein.

In another embodiment of the present invention, the controller 5 is further configured to drive the inverter 3 to apply excitation currents to any two phases of the three-phase asynchronous motor 4 in different time periods, and calculate response voltages generated by the three-phase asynchronous motor 4 according to the excitation currents in different time periods; and according to the excitation current, the response voltage and the third equivalent circuit, the stator resistance of the three-phase asynchronous motor 4 is obtained, and according to the excitation current and the fourth equivalent circuit, the second time constant of the three-phase asynchronous motor 4 is obtained, and according to the first time constant, the second time constant, the leakage inductance and the stator resistance of the three-phase asynchronous motor 4, the mutual inductance and the rotor resistance of the three-phase asynchronous motor 4 are obtained.

In another embodiment of the invention, the controller 5 is specifically configured to:

at the time t0 to ti, driving the inverter 3 to apply a first excitation voltage to any two phases of the three-phase asynchronous motor 4, and obtaining a first response current corresponding to the first equivalent circuit in the time period t0 to ti, wherein i is any positive number;

when the first response current corresponding to the ti moment is equal to a first preset current value, the controller 5 controls the inverter 3 to stop applying a first excitation voltage to the three-phase asynchronous motor 4, and obtains a second response current corresponding to the second equivalent circuit in a ti-ti+1 time period; and obtaining a first time constant of the three-phase asynchronous motor 4 according to the integral of the second response current in the time period of ti to ti+1, the difference value of the second response current in the time period of ti to ti+1 and the second equivalent circuit

Alternatively, the controller 5 may be configured according to the formulaA first time constant Tk of the three-phase asynchronous motor 4 is calculated.

Wherein, rk=rs+rrref, rs is the stator resistance of the three-phase asynchronous motor 4, rref is f ^-1 Rotor equivalent resistance of the equivalent circuit, wherein Tk is a first time constant of the three-phase asynchronous motor 4, and Lsigma is the gamma ^-1 And leakage inductance of the type equivalent circuit, wherein the iInt is the integral of the second response current in the time period from ti to ti+1, and the iDif is the difference value of the second response current in the time period from ti to ti+1.

The offline acquisition system for the parameters of the three-phase asynchronous motor 4 provided by the invention is used for realizing the technical scheme of the method embodiment, and the specific implementation process and principle thereof refer to the description of the method embodiment and are not repeated herein.

In another possible embodiment of the invention, the controller 5 is also specifically configured to:

at the time t0 to tj, driving the inverter 3 to gradually and progressively apply a first excitation current to any two phases of the three-phase asynchronous motor 4 from zero, and calculating a first response voltage corresponding to a time period t0 to tj, wherein j is any positive number;

when the first exciting current corresponding to the tj-tj+1 time period is stabilized at a third preset current value, calculating a second response voltage corresponding to the third equivalent circuit in the tj-tj+1 time period;

At the time tj+1 to tj+2, driving the inverter 3 to apply a second excitation current to any two phases of the three-phase asynchronous motor 4 gradually and progressively from a first excitation current corresponding to the time tj+1, and obtaining a third response voltage corresponding to the time period from tj+1 to tj+2;

when the second excitation current corresponding to the time period from tj+2 to tj+3 is stabilized at a fourth preset current value, calculating a fourth response voltage corresponding to the third equivalent circuit in the time period from tj+2 to tj+3; and obtaining the stator resistance of the three-phase asynchronous motor 4 according to the first exciting current and the second response voltage of the tj to tj+1 time period, the second exciting current and the fourth response voltage of the tj+2 to tj+3 time period and the third equivalent circuit.

Optionally, the controller 5 is specifically configured to perform the following formulaObtaining the stator resistance of the three-phase asynchronous motor 4;

wherein Rs is a stator resistance of the three-phase asynchronous motor 4, I1 and U1 are a first excitation current and a second response voltage of the three-phase asynchronous motor 4 in the tj to tj+1 time period, and I2 and U2 are a second excitation current and a fourth response voltage of the three-phase asynchronous motor 4 in the tj+2 to tj+3 time period, respectively.

Further, the controller 5 of the present embodiment is specifically configured to: at the time tj+3 to tj+4, driving the inverter 3 to gradually and progressively apply a third excitation current to any two phases of the three-phase asynchronous motor 4, the third excitation current being a current that gradually and progressively tapers from a second excitation current corresponding to the time tj+3 to an opposite direction of the second excitation current;

when the third excitation current corresponding to the tj+4 time is equal to a fifth preset current value, driving the inverter 3 to gradually and progressively apply a fourth excitation current to any two phases of the three-phase asynchronous motor 4 from the third excitation current corresponding to the tj+4 time;

when the fourth excitation current corresponding to the tj+5 moment is equal to a negative sixth preset current value, controlling the inverter 3 to stop applying the fourth excitation current to the three-phase asynchronous motor 4; and obtaining a second time constant of the three-phase asynchronous motor 4 according to the integral of the fourth exciting current, the difference value of the fourth exciting current and the fourth equivalent circuit in the time period from tj+4 to tj+5.

Optionally, the controller 5 is specifically configured to perform the following formulaTo calculate a second time constant of the three-phase asynchronous motor 4.

Wherein Ts is a second time constant of the three-phase asynchronous motor 4, lm is a mutual inductance of the three-phase asynchronous motor 4, iInt is an integral of a fourth excitation current in a time period from tj+4 to tj+5, and iDif is a difference value of the fourth excitation current in a time period from tj+4 to tj+5.

Further, the controller 5 of the present embodiment is specifically configured to:

at the time ti+1 to ti+2, driving the inverter 3 to apply a second excitation voltage to any two phases of the three-phase asynchronous motor 4, and obtaining a third response current corresponding to the first equivalent circuit in the time period ti+1 to ti+2;

when the third response current corresponding to the ti+2 moment is equal to a second preset current value, the controller 5 controls the inverter 3 to stop applying a second excitation voltage to the three-phase asynchronous motor 4; and obtaining leakage inductance of the three-phase asynchronous motor 4 according to the integral of the second excitation voltage, the difference value of the third response current and the first equivalent circuit in the time period of ti+1 to ti+2.

Alternatively, the controller 5 follows the formulaObtaining said f ^-1 EtcLeakage inductance L of effect circuit _σ ' and according to the formula->And formula->Calculating to obtain leakage inductance Lsigma of the three-phase asynchronous motor;

Further, the controller 5 is according to the formulaThe rotor resistance R of the motor can be obtained _r 。

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention.

Claims

1. An offline acquisition method for parameters of a three-phase asynchronous motor is characterized by comprising the following steps:

wherein the first equivalent circuit is gamma-shaped according to a three-phase asynchronous motor ^-1 The equivalent circuit is obtained by neglecting mutual inductance of the three-phase asynchronous motor, and the second equivalent circuit is obtained by equivalent of a power supply in the first equivalent circuit into a wire;

the controller obtains a first time constant of the three-phase asynchronous motor according to the response current and the second equivalent circuit, and specifically comprises the following steps:

at the time t0 to ti, the controller drives the inverter to apply a first excitation voltage to any two phases of the three-phase asynchronous motor, and obtains a first response current corresponding to the first equivalent circuit in the time period from t0 to ti, wherein i is any positive number;

When the first response current corresponding to the ti moment is equal to a first preset current value, the controller controls the inverter to stop applying a first excitation voltage to the three-phase asynchronous motor, and obtains a second response current corresponding to the second equivalent circuit in a ti-ti+1 time period;

the controller obtains a first time constant of the three-phase asynchronous motor according to the integral of the second response current in the time period of ti to ti+1, the difference value of the second response current in the time period of ti to ti+1 and the second equivalent circuit;

the controller obtains leakage inductance of the three-phase asynchronous motor according to the excitation voltage, the response current and the first equivalent circuit, and specifically comprises the following steps:

at the time of ti+1 to ti+2, the controller drives the inverter to apply a second excitation voltage to any two phases of the three-phase asynchronous motor, and obtains a third response current corresponding to the first equivalent circuit in the time period of ti+1 to ti+2;

when the third response current corresponding to the ti+2 moment is equal to a second preset current value, the controller controls the inverter to stop applying a second excitation voltage to the three-phase asynchronous motor;

The controller obtains leakage inductance of the three-phase asynchronous motor according to the integral of the second excitation voltage, the difference value of the third response current and the first equivalent circuit in the time period of ti+1 to ti+2.

2. The method according to claim 1, wherein the method further comprises:

the controller drives the inverter to apply exciting currents to any two phases of the three-phase asynchronous motor in different time periods, and calculates response voltages generated by the three-phase asynchronous motor in different time periods according to the exciting currents;

the controller obtains a stator resistance of the three-phase asynchronous motor according to the excitation current, the response voltage and the third equivalent circuit, and obtains a second time constant of the three-phase asynchronous motor according to the excitation current and the fourth equivalent circuit;

wherein the third equivalent circuit is to convert the gamma ^-1 The leakage inductance and the mutual inductance in the equivalent circuit are equivalent to be the equivalent circuit obtained by conducting wires, and the fourth equivalent circuit is obtained by making the gamma-shaped ^-1 The leakage inductance and the power supply in the equivalent circuit are equivalent to be an equivalent circuit obtained by conducting wires;

and the controller obtains the mutual inductance and the rotor resistance of the three-phase asynchronous motor according to the first time constant, the second time constant, the leakage inductance and the stator resistance of the three-phase asynchronous motor.

3. The method according to claim 2, wherein the controller obtains a stator resistance of the three-phase asynchronous motor from the excitation current, the response voltage, and a third equivalent circuit, specifically comprising:

at the time t0 to tj, the controller drives the inverter to gradually and progressively apply a first excitation current to any two phases of the three-phase asynchronous motor from zero, and calculates a first response voltage corresponding to a time period t0 to tj, wherein j is any positive number;

when the first excitation current corresponding to the tj-tj+1 time period is stabilized at a third preset current value, the controller calculates a second response voltage corresponding to the third equivalent circuit in the tj-tj+1 time period;

at the time of tj+1 to tj+2, the controller drives the inverter to apply a second excitation current to any two phases of the three-phase asynchronous motor in a gradual manner from a first excitation current corresponding to the time of tj+1, and obtains a third response voltage corresponding to the time period of tj+1 to tj+2;

when the second excitation current corresponding to the time period from tj+2 to tj+3 is stabilized at a fourth preset current value, the controller calculates a fourth response voltage corresponding to the third equivalent circuit in the time period from tj+2 to tj+3;

The controller obtains the stator resistance of the three-phase asynchronous motor according to the first exciting current and the second response voltage of the tj to tj+1 time period, the second exciting current and the fourth response voltage of the tj+2 to tj+3 time period and the third equivalent circuit.

4. A method according to claim 3, characterized in that the controller obtains a second time constant of the three-phase asynchronous motor from the excitation current and a fourth equivalent circuit, comprising in particular:

at the time tj+3 to tj+4, the controller drives the inverter to gradually and progressively apply a third exciting current to any two phases of the three-phase asynchronous motor, wherein the third exciting current is a current which gradually and progressively changes from a second exciting current corresponding to the time tj+3 to the opposite direction of the second exciting current;

when the third excitation current corresponding to the tj+4 moment is equal to a fifth preset current value, the controller drives the inverter to gradually and progressively apply a fourth excitation current to any two phases of the three-phase asynchronous motor from the third excitation current corresponding to the tj+4 moment;

when the fourth excitation current corresponding to the tj+5 moment is equal to a sixth preset current value, the controller controls the inverter to stop applying the fourth excitation current to the three-phase asynchronous motor;

And the controller obtains a second time constant of the three-phase asynchronous motor according to the integral of the fourth exciting current, the difference value of the fourth exciting current and a fourth equivalent circuit in the time period from tj+4 to tj+5.

5. The method according to claim 1, wherein the controller obtains a first time constant of the three-phase asynchronous motor from an integral of the second response current in the time period ti to ti+1, a difference of the second response current in the time period ti to ti+1, and the second equivalent circuit, in particular:

the controller is according to the formulaObtaining a first time constant of the three-phase asynchronous motor;

6. The method according to claim 1, wherein the controller obtains the leakage inductance of the three-phase asynchronous motor from the integral of the second excitation voltage, the difference of the third response currents, and the first equivalent circuit over the period of ti+1 to ti+2, in particular:

The controlThe device is according to the formulaObtaining said f ^-1 Leakage inductance L of equivalent circuit _σ ' and according to the formulaAnd formula->Obtaining leakage inductance Lsigma of the three-phase asynchronous motor;

7. A method according to claim 3, characterized in that the controller obtains the stator resistance of the three-phase asynchronous motor from the first excitation current and the second response voltage of the tj to tj+1 time period, the second excitation current and the fourth response voltage of the tj+2 to tj+3 time period, and the third equivalent circuit, in particular:

the controller is according to the formulaObtaining the stator resistance of the three-phase asynchronous motor;

8. The method according to claim 4, characterized in that the controller obtains the second time constant of the three-phase asynchronous motor from the integral of the fourth excitation current, the difference of the fourth excitation current and the fourth equivalent circuit over the period tj+4 to tj+5, in particular:

the controller is according to the formulaObtaining a second time constant of the three-phase asynchronous motor;

9. An offline acquisition system for parameters of a three-phase asynchronous motor, comprising: the device comprises a rectifier, an inverter, a controller, a voltage sensor, a current sensor, a direct-current supporting capacitor and a three-phase asynchronous motor;

the controller is specifically configured to drive the inverter to apply a first excitation voltage to any two phases of the three-phase asynchronous motor at time t0 to ti, and obtain a first response current corresponding to the first equivalent circuit in a time period from t0 to ti, where i is any positive number;

when the first response current corresponding to the ti moment is equal to a first preset current value, the controller controls the inverter to stop applying a first excitation voltage to the three-phase asynchronous motor, and obtains a second response current corresponding to the second equivalent circuit in a ti-ti+1 time period; obtaining a first time constant of the three-phase asynchronous motor according to the integral of the second response current in the time period of ti to ti+1, the difference value of the second response current in the time period of ti to ti+1 and the second equivalent circuit;

The controller is further specifically configured to drive the inverter to apply a second excitation voltage to any two phases of the three-phase asynchronous motor at time ti+1 to ti+2, and obtain a third response current corresponding to the first equivalent circuit in a time period ti+1 to ti+2;

when the third response current corresponding to the ti+2 moment is equal to a second preset current value, the controller controls the inverter to stop applying a second excitation voltage to the three-phase asynchronous motor; and obtaining leakage inductance of the three-phase asynchronous motor according to the integral of the second excitation voltage, the difference value of the third response current and the first equivalent circuit in the time period of ti+1 to ti+2.

10. The system of claim 9, wherein the system further comprises a controller configured to control the controller,

the controller is also used for driving the inverter to apply exciting currents to any two phases of the three-phase asynchronous motor in different time periods and calculating response voltages generated by the three-phase asynchronous motor according to the exciting currents in different time periods; the stator resistance of the three-phase asynchronous motor is obtained according to the excitation current, the response voltage and the third equivalent circuit, the second time constant of the three-phase asynchronous motor is obtained according to the excitation current and the fourth equivalent circuit, and the mutual inductance and the rotor resistance of the three-phase asynchronous motor are obtained according to the first time constant, the second time constant, the leakage inductance and the stator resistance of the three-phase asynchronous motor;

11. The system of claim 10, wherein the controller is further specifically configured to:

at the time t0 to tj, driving the inverter to gradually and progressively apply a first excitation current to any two phases of the three-phase asynchronous motor from zero, and calculating a first response voltage corresponding to a time period t0 to tj, wherein j is any positive number;

at the time of tj+1 to tj+2, driving the inverter to apply a second excitation current to any two phases of the three-phase asynchronous motor gradually and progressively from a first excitation current corresponding to the time of tj+1, and obtaining a third response voltage corresponding to the time period of tj+1 to tj+2;

when the second excitation current corresponding to the time period from tj+2 to tj+3 is stabilized at a fourth preset current value, calculating a fourth response voltage corresponding to the third equivalent circuit in the time period from tj+2 to tj+3; and obtaining the stator resistance of the three-phase asynchronous motor according to the first exciting current and the second response voltage of the tj to tj+1 time period, the second exciting current and the fourth response voltage of the tj+2 to tj+3 time period and the third equivalent circuit.

12. The system of claim 11, wherein the controller is further specifically configured to:

at the time tj+3 to tj+4, driving the inverter to gradually and progressively apply a third exciting current to any two phases of the three-phase asynchronous motor, wherein the third exciting current is a current which gradually and progressively changes from a second exciting current corresponding to the time tj+3 to the opposite direction of the second exciting current;

when the third excitation current corresponding to the tj+4 moment is equal to a fifth preset current value, driving the inverter to gradually and progressively apply a fourth excitation current to any two phases of the three-phase asynchronous motor from the third excitation current corresponding to the tj+4 moment;

when the fourth excitation current corresponding to the tj+5 moment is equal to a sixth preset current value, controlling the inverter to stop applying the fourth excitation current to the three-phase asynchronous motor; and obtaining a second time constant of the three-phase asynchronous motor according to the integral of the fourth exciting current, the difference value of the fourth exciting current and the fourth equivalent circuit in the time period from tj+4 to tj+5.

13. The system of claim 9, wherein the controller is specifically configured to Obtaining a first time constant of the three-phase asynchronous motor;

14. The system of claim 13, wherein the controller is specifically configured toObtaining said f ^-1 Leakage inductance L of equivalent circuit _σ ' and according to the formula->Sum formulaObtaining leakage inductance Lsigma of the three-phase asynchronous motor;

15. The system of claim 11, wherein the controller is specifically configured to Obtaining the stator resistance of the three-phase asynchronous motor;

16. The system of claim 15, wherein the controller is specifically configured toObtaining a second time constant of the three-phase asynchronous motor;