CN104836502A - Alternating-current servo motor system and winding three-phase current reconstruction method thereof - Google Patents

Abstract

The invention provides an alternating-current servo motor system and a winding three-phase current reconstruction method thereof. The alternating-current servo motor system comprises a three-phase full-bridge inverter control topology and a permanent magnet synchronous motor which is connected with an alternating-current output end of the three-phase full-bridge inverter control topology. The three-phase full-bridge inverter control topology comprises a three-phase bridge inverter circuit, a direct-current power supply, and a current sensor. The direct-current power supply is connected in parallel with a direct-current side of the three-phase bridge inverter circuit which includes a phase A, a phase B and a phase C. The current sensor is used for detecting the sum of current flowing through a phase-B upper bridge arm and current flowing through a phase-C upper bridge arm and detecting the value of current flowing through a phase-C lower bridge arm, or is used for detecting the value of current flowing through the phase-C upper bridge arm and detecting the sum of current flowing through a phase-B lower bridge arm and current flowing through the phase-C lower bridge arm. By adopting the system and the method of the invention, the number of current sensors used is reduced, the system size is reduced, the cost is lowered, and the reliability of a driving control system is improved.

Description

An AC servo motor system and its winding three-phase current reconstruction method

technical field

The invention relates to the technical field of AC motor drive and control, in particular to an AC servo motor system and a method for reconfiguring the three-phase current of its windings.

Background technique

With the development of microprocessor technology, power electronic devices, motor manufacturing process and the continuous emergence of high-performance rare earth permanent magnet materials, the AC servo system has made great progress. At the same time, with the introduction of the modern control theory typified by the vector control algorithm, the control performance of the AC servo system has surpassed the traditional DC servo system. And compared with other types of motors, the reliability and power density of permanent magnet synchronous motors are superior in many aspects, and because of these advantages, they have been widely used in industrial fields, such as robot control, CNC machine tools, office automation, military weapons Follow the system and aerospace fields, etc. However, due to the high price of the permanent magnet synchronous motor servo system, the widening of its application field is limited to a certain extent. Therefore, how to reduce the cost of the AC servo system while ensuring its high performance is of great significance.

In the permanent magnet synchronous motor servo system using vector control, in addition to the microcontroller and power circuit, it is also necessary to complete the detection of the rotor position, speed and winding current in real time to complete the closed-loop control. The position sensor for rotor position detection mainly includes: photoelectric code disc, rotary transformer, linear Hall device, etc. However, the application of these sensors undoubtedly increases the cost of the system and increases the complexity of the signal processing circuit. Therefore, in the 1980s, people began to devote themselves to the research of position sensorless technology, and proposed a series of position detection methods, and basically completed the solution from high speed to low speed operation area. While omitting the position sensor, how to reduce the number of current sensors becomes the focus of the next research. In order to obtain the phase current of the motor, the traditional method is to install two to three current sensors at the winding end to detect the phase winding current, and to install a current sensor on the DC bus side as a protection signal, which not only greatly increases the system size, improves It increases the cost, complicates the signal conditioning circuit, and the product difference between multiple sensors also brings errors to the current detection. In recent years, phase current reconstruction algorithms based on single current sensors have been emerging, but they are all based on bus current sensor current reconstruction, which has fatal blind spots. Therefore, the phase current reconstruction technology of AC servo motor based on single current sensor has important research value and engineering significance.

Contents of the invention

In view of the deficiencies in the above problems, the technical problem to be solved by the present invention is: in the motor phase current detection process, due to the use of a large number of current sensors, the system volume is too large, the cost is increased, and the signal conditioning The circuit structure is complex, and the product differences between multiple current sensors will also bring errors to current detection.

In order to solve the above problems, one aspect of the present invention provides an AC servo motor system, including a three-phase full-bridge inverter control topology and a permanent magnet synchronous motor, the permanent magnet synchronous motor and the three-phase full-bridge inverter control The AC output terminal of the topology is connected, wherein the three-phase full-bridge inverter control topology includes a three-phase bridge inverter circuit, a DC power supply and a current sensor, and the DC power supply and the three-phase bridge inverter circuit The DC side is connected in parallel, the three-phase bridge inverter circuit includes A phase, B phase and C phase, and the current sensor is used to detect the current flowing through the upper bridge arm of the B phase and the upper bridge arm of the C phase and, and detecting the current value flowing through the C-phase lower bridge arm; or detecting the current value flowing through the C-phase upper bridge arm, and detecting the current flowing through the B-phase lower bridge arm and the C-phase lower bridge arm Arm current and .

Preferably, one end of the current sensor is connected to the connection line between the upper bridge arm of the A phase and the upper bridge arm of the B phase, so as to detect the current flowing through the upper bridge arm of the B phase and the upper bridge arm of the C phase. The other end of the current sensor is connected to the connection line between the lower bridge arm of the B phase and the lower bridge arm of the C phase to detect the current value flowing through the lower bridge arm of the C phase.

Preferably, one end of the current sensor is connected to the connection line between the upper bridge arm of the B phase and the upper bridge arm of the C phase, so as to detect the current value flowing through the upper bridge arm of the C phase, and the current sensor The other end of is connected to the connection line of the A-phase lower bridge arm and the B-phase lower bridge arm to detect the sum of the currents flowing through the B-phase lower bridge arm and the C-phase lower bridge arm.

Another aspect of the present invention provides a method for reconfiguring the winding three-phase current based on an AC servo motor system, which includes the following steps:

S10. Using the voltage space vector to realize the vector control mode, the three-phase symmetrical winding voltages U _a , U _b , U _c are obtained through Clarke inverse transformation of the voltages U _α and U _β in the given two-phase orthogonal coordinate system;

S20. Calculate the sum of the amplitudes of the two voltage vectors in the output voltage vectors of the three-phase symmetrical winding voltages. If the sum of the amplitudes of the two voltage vectors does not exceed threshold one, execute step S30; if the sum of the amplitudes of the two voltage vectors exceeds threshold one, execute Step S40;

S30, during the two zero-vector action periods in each switching cycle, respectively sample the output values of the current sensors through the AD converter, so as to obtain the current values of the three-phase windings;

S40. If the sum of the amplitudes of the two voltage vectors exceeds threshold one, then select a sampling method according to the position of the current voltage vector, and if the amplitudes of the two voltage vectors in the switching cycle are both greater than threshold two, then perform step S50; if In the output voltage vector in the linear modulation area, the sum of the amplitudes of the two voltage vectors exceeds the threshold value 1, then select the sampling method according to the position of the current voltage vector, if any one of the amplitudes of the two voltage vectors in the switching cycle is less than the threshold value Two, execute step S60;

S50. Install another single current sensor on the DC bus side. During the two voltage vector action periods, respectively use the AD converter to sample the output value of the current sensor on the bus, and determine the two sampling times according to the sector position where the voltage vector is located. The corresponding current value, so as to obtain the current value of the three-phase winding;

S60. Obtain the three-phase winding current by using a sliding mode current observer plus feedback correction.

Preferably, in the step S20, threshold one is determined by the on-off delay time t _d of the power device, the current setup time t _set and the minimum sampling and holding time t _s&h of the AD converter, and the specific calculation method is:

Among them, U _thd1 is the voltage vector threshold one, and U _amp is the maximum magnitude of the basic voltage vector.

Preferably, in the step S40, the second threshold is determined by the on-off delay time t _d of the power device, the current setup time t _set and the minimum sampling and holding time t _s&h of the AD converter, and the specific calculation method is:

Among them, U _thd2 is the voltage vector threshold value 2, and U _amp is the maximum magnitude of the basic voltage vector.

Preferably, in said step S60, the following steps are also included:

S601. According to the voltage balance equation of the AC motor:

$\left\{\begin{array}{c}{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; L</span>}\frac{{\mathrm{<span\; class="notranslate">\; di</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}}{\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}\\ {\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; L</span>}\frac{{\mathrm{<span\; class="notranslate">\; di</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}}{\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}\\ {\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; L</span>}\frac{{\mathrm{<span\; class="notranslate">\; di</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}}{\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}\end{array}\right.$

Build an open-loop current observer:

$\left\{\begin{array}{c}\frac{{\mathrm{<span\; class="notranslate">\; di</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}}{\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; )</span>\\ \frac{{\mathrm{<span\; class="notranslate">\; di</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}}{\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; )</span>\\ \frac{{\mathrm{<span\; class="notranslate">\; di</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}}{\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; )</span>\end{array}\right.$

Where u _a , u _b , uc are three-phase voltages, _ia , i _b , _ic are three-phase currents, e _a , e _b , _{e c are} opposite potentials, R is the motor winding resistance, L is the winding inductance;

S602. If the rotor position and angular velocity of the motor are known, the three opposite potentials can be calculated by the following formula:

Where e _a , e _b , e _c are the opposite electromotive force, k _e is the counter electromotive force coefficient, ω _r is the rotor angular velocity, θ is the rotor position angle;

S603. Establish a closed-loop sliding mode current sensor based on the open-loop observer:

$\left\{\begin{array}{c}\frac{{\mathrm{<span\; class="notranslate">\; di</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}}{\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; )</span>\\ \frac{{\mathrm{<span\; class="notranslate">\; di</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}}{\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; )</span>\\ \frac{{\mathrm{<span\; class="notranslate">\; di</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}}{\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; )</span>\end{array}\right.$

S604. Obtain the current of a phase winding through sampling, and obtain the current error value according to the estimation method of the following formula, taking the A-phase current as an example:

Among them, Z is the sliding mode switch control amount, _k is the control gain, ia, _ib and _ic are the actual three-phase current, is the observed three-phase current.

Compared with the prior art, the present invention has the following advantages:

The invention only uses one current sensor, and in the process of detecting the motor phase current, the current of the detection line is detected at a specific moment, and then the current value of the three-phase winding can be obtained through calculation. In addition, because only one current sensor is used, compared with the prior art, the present invention can reduce the number of current sensors used, reduce the volume of the system, reduce the cost, make the structure of the signal conditioning circuit simple and clear, and avoid the problem caused by multiple current sensors. There are product differences among them, which will bring errors to current detection, thereby improving the reliability of the drive control system.

Based on the three-phase current reconstruction method in the present invention, in the process of detecting the phase current of the motor, it is only necessary to connect one current sensor used with the connecting lines of different phase bridge arms, so that the corresponding current value and the corresponding current value can be detected. current and to complete the reconstruction of the relevant phase currents. Compared with the prior art, the present invention can reduce the number of current sensors used, reduce the volume of the system, reduce the cost, make the structure of the signal conditioning circuit simple and clear, and avoid multiple There are product differences between current sensors that bring errors to current detection, thereby improving the reliability of the drive control system.

Description of drawings

Fig. 1 is a schematic diagram of the circuit structure of an embodiment of the present invention;

Fig. 2 is a schematic diagram of the circuit structure of another embodiment of the present invention;

Fig. 3 is that the AD converter of the present invention illustrates the specific sampling time of the current sensor;

Fig. 4 is a schematic diagram of a blind zone for current reconstruction using a bus current sensor in the present invention;

Fig. 5 is a schematic diagram of a blind area for current reconstruction using the installation method of the current sensor in Fig. 1 or Fig. 2 according to the present invention;

Fig. 6 is a schematic diagram of a blind zone for current reconstruction using the installation method of the current sensor in Fig. 1 or Fig. 2 and the integration of the bus current sensor in the present invention;

Fig. 7 is the flow chart of the reconstruction method of winding three-phase current of the present invention;

Fig. 8 is a schematic diagram of the simulation results obtained by using the observer to obtain the phase current in the present invention.

Description of main component symbols:

1-DC power supply 2-Three-phase bridge inverter circuit 3-Current sensor

4-Permanent magnet synchronous motor

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and examples, but the given examples are not intended to limit the present invention.

As shown in Figure 1, the embodiment of the present invention comprises three-phase full-bridge inverter control topology and permanent magnet synchronous motor 4, and permanent magnet synchronous motor 4 is connected with the AC output end of three-phase full-bridge inverter control topology, wherein , the three-phase full-bridge inverter control topology includes a three-phase bridge inverter circuit 2, a DC power supply 1 and a current sensor 3, the DC power supply 1 is connected in parallel with the DC side of the three-phase bridge inverter circuit 2, and the three-phase bridge inverter circuit Transformer circuit 2 includes three phases, namely A phase, B phase and C phase. One end of current sensor 3 is connected to the connection line between the upper bridge arm of A phase and the upper bridge arm of B phase, and detects the current flowing through the upper bridge arm of phase B and the C phase. The current sum of the upper bridge arm of the phase is connected to the connection line between the lower bridge arm of the B phase and the lower bridge arm of the C phase to detect the current value flowing through the lower bridge arm of the C phase.

The current sensor 3 is an electrically isolated current sensor, and various electrically isolated current sensors can be selected, such as Hall effect sensors or current transformers.

Each phase bridge arm of the three-phase bridge inverter circuit 2 is composed of two fully-controlled switching devices connected in series and diodes connected in anti-parallel with the two fully-controlled switching devices. Various types of fully-controlled switching devices can be selected. Example: Insulated Gate Bipolar Transistor.

As shown in Figure 2, in the present embodiment, comprise three-phase full-bridge inverter control topology and permanent magnet synchronous motor 4, permanent magnet synchronous motor 4 is connected with the AC output end of three-phase full-bridge inverter control topology, wherein , the three-phase full-bridge inverter control topology includes a three-phase bridge inverter circuit 2, a DC power supply 1 and a current sensor 3, the DC power supply 1 is connected in parallel with the DC side of the three-phase bridge inverter circuit 2, and the three-phase bridge inverter circuit Transformer circuit 2 includes three phases, namely A phase, B phase and C phase. One end of current sensor 3 is connected to the connection line between the upper bridge arm of B phase and the upper bridge arm of C phase to detect the current flowing through the upper bridge arm of C phase. value, the other end is connected to the connection line between the lower bridge arm of phase A and the lower bridge arm of phase B to detect the sum of the current flowing through the lower bridge arm of phase B and the lower bridge arm of phase C.

The current sensor 3 is an electrically isolated current sensor, and various electrically isolated current sensors can be selected, such as Hall effect sensors or current transformers.

Each phase bridge arm of the three-phase bridge inverter circuit 2 is composed of two fully-controlled switching devices connected in series and diodes connected in anti-parallel with the two fully-controlled switching devices. Various types of fully-controlled switching devices can be selected. Such as insulated gate bipolar transistors.

As shown in FIG. 7, this embodiment provides a method for reconfiguring the three-phase current of a winding, which includes the following steps:

S10. Using the voltage space vector to realize the vector control mode, the three-phase symmetrical winding voltages U _a , U _b , U _c are obtained by Clarke inverse transformation of the voltages U _α and U _β in the given two-phase orthogonal coordinate system:

$\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}\\ {\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}\\ {\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}\end{array}\right]<span\; class="notranslate">\; =</span>\left[\begin{array}{cc}\mathrm{<span\; class="notranslate">\; 0</span>}& \mathrm{<span\; class="notranslate">\; 1</span>}\\ <span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}& \sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}\\ <span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}& <span\; class="notranslate">\; -</span>\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}\end{array}\right]\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}\\ {\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}\end{array}\right]$

The sector label where the output voltage vector is located is obtained by calculating Sign(U _a )+2×Sign(U _b )+4×Sign(U _c ), where Sign() is a sign function.

S20. Calculate the sum of the amplitudes of the two effective basic voltage vectors in the output voltage vectors of the three-phase symmetrical winding voltages. If the sum of the amplitudes of the two effective basic voltage vectors does not exceed threshold one, then perform step S30; if the sum of the amplitudes of the two effective basic voltage vectors exceeds the threshold One, then execute step S40;

Threshold 1 is determined by the on-off delay time t _d of the power device, the current setup time t _set and the minimum sampling and holding time t _s&h of the AD converter. The specific calculation method is:

Among them, U _thd1 is the voltage vector threshold one, and U _amp is the maximum magnitude of the basic voltage vector.

S30. Calculate the sum of the amplitudes of the two effective basic voltage vectors in the output voltage vector, if it does not exceed the threshold value one, then in the non-shaded area shown in Figure 5, there are two U ₀ and U ₇ in each switching cycle During the action period of the zero vector, at the time i _sam1 and i _sam2 shown in Figure 3, the output value of the current sensor is sampled through the AD converter respectively, and the current value sampled during the U ₀ period is the C-phase current value. The current value sampled in the U ₇ period is the B and C phase currents, and then the B phase current value is obtained. According to Kirchhoff’s current law _{ia +i b +i c = 0} , the A phase current value can be calculated to obtain the three The current value of the phase winding.

S40. If the sum of the amplitudes of the two effective basic voltage vectors exceeds threshold one, select a sampling method according to the position of the current voltage vector, and if the amplitudes of the two effective basic voltage vectors in the switching period are both greater than threshold two, execute Step S50; if the sum of the amplitudes of the two effective basic voltage vectors in the output voltage vector appears in the linear modulation region exceeds the threshold value one, then select the sampling method according to the position of the current voltage vector, if the two effective basic voltage vectors in the switching cycle If any one of the magnitudes of the vector is smaller than the threshold two, step S60 is executed;

The second threshold is determined by the on-off delay time t _d of the power device, the current setup time t _set and the minimum sampling and holding time t _s&h of the AD converter. The specific calculation method is:

Among them, U _thd2 is the voltage vector threshold value 2, and U _amp is the maximum magnitude of the basic voltage vector.

S50. If the sum of the amplitudes of the two effective basic voltage vectors exceeds threshold one, then select a sampling method according to the position of the current voltage vector. If the amplitudes of the two effective basic voltage vectors in the switching cycle are both greater than threshold two, then as In the non-shaded area shown in Figure 4, another single current sensor is installed on the side of the DC bus, which can be electrically isolated or non-isolated. During the two effective basic voltage vector action periods, that is, i _sam3 as shown in Figure 3 and i _sam4 time, the output value of the current sensor on the bus is sampled through the AD converter respectively, and the current value corresponding to the two samplings is determined according to the sector position of the voltage vector, and the current value corresponding to the two samplings is determined by checking the table below .

Taking the third sector as an example, the two current samples are A-phase current i _a and C-phase current- _ic respectively, and the B-phase current can be calculated according to Kirchhoff’s current law i _a +i _b +i _c =0 value, so as to obtain the current value of the three-phase winding.

After adding the bus current sensor, it also has the function of simplifying the overcurrent protection process. If the bus current sensor is not added, the three-phase winding current can only be calculated and then the current limiting control is performed respectively.

S60. If the sum of the amplitudes of the two effective basic voltage vectors in the output voltage vector exceeds the threshold value 1 in the linear modulation region, select the sampling mode according to the position of the current voltage vector. If the two effective basic voltage vectors in the switching cycle If any one of the amplitudes is smaller than threshold two, the three-phase winding current is obtained by using a sliding mode current observer plus feedback correction.

Specific steps are as follows:

S601. According to the voltage balance equation of the AC motor:

$\left\{\begin{array}{c}{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; L</span>}\frac{{\mathrm{<span\; class="notranslate">\; di</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}}{\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}\\ {\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; L</span>}\frac{{\mathrm{<span\; class="notranslate">\; di</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}}{\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}\\ {\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; L</span>}\frac{{\mathrm{<span\; class="notranslate">\; di</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}}{\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}\end{array}\right.$

Build an open-loop current observer:

$\left\{\begin{array}{c}\frac{{\mathrm{<span\; class="notranslate">\; di</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}}{\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; )</span>\\ \frac{{\mathrm{<span\; class="notranslate">\; di</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}}{\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; )</span>\\ \frac{{\mathrm{<span\; class="notranslate">\; di</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}}{\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; )</span>\end{array}\right.$

Where u _a , u _b , uc are three-phase voltages, _ia , i _b , _ic are three-phase currents, e _a , e _b , _{e c are} opposite potentials, R is the motor winding resistance, L is the winding inductance;

S602. If the rotor position and angular velocity of the motor are known, the three opposite potentials can be calculated by the following formula:

Where e _a , e _b , e _c are the opposite electromotive force, k _e is the counter electromotive force coefficient, ω _r is the rotor angular velocity, θ is the rotor position angle;

S603. Due to changes in parameters such as motor resistance and inductance, there is a deviation in the current value obtained by the open-loop current observer. It is necessary to perform feedback correction based on the actual detected current value. Therefore, a closed-loop sliding mode is established on the basis of the open-loop observer Current sensor:

$\left\{\begin{array}{c}\frac{{\mathrm{<span\; class="notranslate">\; di</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}}{\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; )</span>\\ \frac{{\mathrm{<span\; class="notranslate">\; di</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}}{\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; )</span>\\ \frac{{\mathrm{<span\; class="notranslate">\; di</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}}{\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; )</span>\end{array}\right.$

S604. Obtain the current of a phase winding through sampling, and obtain the current error value according to the estimation method of the following formula, taking the A-phase current as an example:

Among them, Z is the sliding mode switch control amount, _k is the control gain, ia, _ib and _ic are the actual three-phase current, In order to observe the obtained three-phase current, the simulation results of the sliding mode current observer method are shown in Figure 8.

The above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention will not be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (7)

1. an AC servo motor system, comprising a three-phase full-bridge inverter control topology and a permanent magnet synchronous motor, the permanent magnet synchronous motor is connected with the AC output of the three-phase full-bridge inverter control topology, its It is characterized in that the three-phase full-bridge inverter control topology includes a three-phase bridge inverter circuit, a DC power supply and a current sensor, the DC power supply is connected in parallel with the DC side of the three-phase bridge inverter circuit, and the The three-phase bridge inverter circuit includes A phase, B phase and C phase, and the current sensor is used to detect the sum of the current flowing through the upper bridge arm of the B phase and the upper bridge arm of the C phase, and detect the sum of the current flowing through the upper bridge arm of the C phase. the current value of the C-phase lower bridge arm; or detect the current value flowing through the C-phase upper bridge arm, and detect the sum of the currents flowing through the B-phase lower bridge arm and the C-phase lower bridge arm. 2. The AC servo motor system according to claim 1, wherein one end of the current sensor is connected to the connection line between the upper bridge arm of the A phase and the upper bridge arm of the B phase to detect the current flowing through The current sum of the B-phase upper bridge arm and the C-phase upper bridge arm, the other end of the current sensor is connected to the connection line between the B-phase lower bridge arm and the C-phase lower bridge arm to detect The current value flowing through the lower bridge arm of the C phase. 3. The AC servo motor system according to claim 1, wherein one end of the current sensor is connected to the connection line between the upper bridge arm of the B phase and the upper bridge arm of the C phase to detect the current flowing through The current value of the upper bridge arm of the C phase, the other end of the current sensor is connected to the connection line between the lower bridge arm of the A phase and the lower bridge arm of the B phase, so as to detect the current value flowing through the lower bridge arm of the B phase. arm and the current sum of the C-phase lower arm. 4. A reconfiguration method based on the winding three-phase current of the AC servo motor system described in claim 2 or 3, is characterized in that, comprises the following steps: S10. Using the voltage space vector to realize the vector control mode, the three-phase symmetrical winding voltages U _a , U _b , U _c are obtained through Clarke inverse transformation of the voltages U _α and U _β in the given two-phase orthogonal coordinate system; S20. Calculate the sum of the amplitudes of the two voltage vectors in the output voltage vectors of the three-phase symmetrical winding voltages. If the sum of the amplitudes of the two voltage vectors does not exceed threshold one, execute step S30; if the sum of the amplitudes of the two voltage vectors exceeds threshold one, execute Step S40; S30, during each switching period of the two zero-vector action periods, respectively through AD conversion The device samples the output value of the current sensor to obtain the current value of the three-phase winding; S40. If the sum of the amplitudes of the two voltage vectors exceeds threshold one, then select a sampling method according to the position of the current voltage vector, and if the amplitudes of the two voltage vectors in the switching cycle are both greater than threshold two, then perform step S50; if In the output voltage vector in the linear modulation area, the sum of the amplitudes of the two voltage vectors exceeds the threshold value 1, then select the sampling method according to the position of the current voltage vector, if any one of the amplitudes of the two voltage vectors in the switching cycle is less than the threshold value Two, execute step S60; S50. Install another single current sensor on the DC bus side. During the two voltage vector action periods, respectively use the AD converter to sample the output value of the current sensor on the bus, and determine the two sampling times according to the sector position where the voltage vector is located. The corresponding current value, so as to obtain the current value of the three-phase winding; S60. Obtain the three-phase winding current by using a sliding mode current observer plus feedback correction. 5. The method for reconfiguring the winding three-phase current as claimed in claim 4, characterized in that, in the step S20, threshold one is determined by the on-off delay time td of the power device, the current set-up time _{t set} and AD The minimum sampling and holding time t _s&h of the converter is determined, and the specific calculation method is: Among them, U _thd1 is the voltage vector threshold one, and U _amp is the maximum magnitude of the basic voltage vector. 6. The method for reconfiguring the winding three-phase current as claimed in claim 4, characterized in that, in the step S40, the second threshold value is determined by the on-off delay time t _d of the power device, the current set-up time t _set and AD The minimum sampling and holding time t _s&h of the converter is determined, and the specific calculation method is: Among them, U _thd2 is the voltage vector threshold value 2, and U _amp is the maximum magnitude of the basic voltage vector. 7. The reconfiguration method of winding three-phase current as claimed in claim 4, is characterized in that, in described step S60, also comprises the following steps: S601. According to the voltage balance equation of the AC motor: $\left\{\begin{array}{c}{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; L</span>}\frac{{\mathrm{<span\; class="notranslate">\; di</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}}{\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}\\ {\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; L</span>}\frac{{\mathrm{<span\; class="notranslate">\; di</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}}{\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}\\ {\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; L</span>}\frac{{\mathrm{<span\; class="notranslate">\; di</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}}{\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}\end{array}\right.$ Build an open-loop current observer: $\left\{\begin{array}{c}\frac{{\mathrm{<span\; class="notranslate">\; di</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}}{\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; )</span>\\ \frac{{\mathrm{<span\; class="notranslate">\; di</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}}{\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; )</span>\\ \frac{{\mathrm{<span\; class="notranslate">\; di</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}}{\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; )</span>\end{array}\right.$ Where u _a , u _b , uc are three-phase voltages, _ia , i _b , _ic are three-phase currents, e _a , e _b , _{e c are} opposite potentials, R is the motor winding resistance, L is the winding inductance; S602. If the rotor position and angular velocity of the motor are known, the three opposite potentials can be calculated by the following formula: Where e _a , e _b , e _c are the opposite electromotive force, k _e is the counter electromotive force coefficient, ω _r is the rotor angular velocity, θ is the rotor position angle; S603. Establish a closed-loop sliding mode current sensor based on the open-loop observer: $\left\{\begin{array}{c}\frac{{\mathrm{<span\; class="notranslate">\; di</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}}{\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; )</span>\\ \frac{{\mathrm{<span\; class="notranslate">\; di</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}}{\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; )</span>\\ \frac{{\mathrm{<span\; class="notranslate">\; di</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}}{\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; )</span>\end{array}\right.$ S604. Obtain the current of a phase winding through sampling, and obtain the current error value according to the estimation method of the following formula, taking the A-phase current as an example: Among them, Z is the sliding mode switch control amount, _k is the control gain, ia, _ib and _ic are the actual three-phase current, is the observed three-phase current.