CN113239593B - Design method suitable for optimizing efficiency of water-filled submersible motor - Google Patents

Abstract

The invention discloses a design method suitable for optimizing the efficiency of a water-filled submersible motor. Preliminary scheme of electromagnetic design of water-filled submersible motor; by optimizing the ratio of diameter to shaft length and air gap length of the water-filled submersible motor, the water friction loss of the water-filled submersible motor is reduced and the motor efficiency is improved. The invention adopts a two-dimensional time-harmonic field to analyze the influence of the stator inner diameter and air gap length on the electromagnetic performance and electromagnetic loss of the submersible motor; The change of motor performance parameters, combined with the requirements of actual working conditions, determines the size of the motor, which can effectively reduce the water friction loss of the water-filled submersible motor and improve the efficiency of the water-filled submersible motor.

Description

A design method for efficiency optimization of water-filled submersible motors

technical field

The invention relates to the field of motor optimization, in particular to a design method suitable for efficiency optimization of a water-filled submersible motor.

Background technique

At present, the design process of the water-filled submersible motor mainly adopts the empirical method. According to the existing induction motor, the motor is designed through the main size formula. Unlike traditional motors, the motor cavity is filled with cooling water due to the influence of the working environment. The water friction loss when the motor is running is much greater than the air friction loss in the air-cooled motor, which is one of the important factors leading to the low efficiency of the submersible motor. Losses have a big impact.

SUMMARY OF THE INVENTION

From this point of view, the purpose of the present invention is to propose a design method suitable for the efficiency optimization of water-filled submersible motors, which can effectively optimize the redesign stage by selecting parameters such as the inner diameter, shaft length and air gap length of the submersible motor stator. Reduce the water friction loss of the water-filled submersible motor and improve the motor efficiency.

The object of the present invention is achieved through the following technical solutions:

The design method for optimizing the efficiency of a water-filled submersible motor includes the following steps:

S1: According to the product specifications and technical requirements of the water-filled submersible motor, the preliminary scheme for the electromagnetic design of the water-filled submersible motor is given, including;

S11, select the three circles and shaft length of the motor according to the technical parameters of the motor and the actual working conditions;

S12, select the material of the motor core, winding and bar;

S13, select the slot type, size, and wire diameter of the stator and rotor of the motor;

S2: Establish a two-dimensional time-harmonic field simulation model of a water-filled submersible motor:

The method for establishing a two-dimensional time-harmonic field simulation model of a water-filled submersible motor includes: inputting the size of the motor and the material properties of each part into the simulation software Flux, obtaining a two-dimensional model, dividing the two-dimensional model into a grid, and performing grid division on the two-dimensional model. Perform time-harmonic field simulation;

S3: Draw the water friction loss curve of the water-filled submersible motor:

The method for drawing the water friction loss curve of the water-filled submersible motor includes: according to the formula of the water friction loss of the water-filled submersible motor, respectively drawing the curve of the water friction loss with the inner diameter of the stator and the length of the air gap;

S4: Fitting the loss curve of the water-filled submersible motor:

The method for fitting the loss curve of the water-filled submersible motor includes: fitting the electrical loss curve through the least squares method according to the simulation result obtained in step S2, and comparing the electrical loss with the change curve of the inner diameter of the stator and the length of the air gap, respectively, and the water friction loss. Add the curves with the inner diameter of the stator and the length of the air gap to get the curve of the motor loss changing with the inner diameter of the stator and the length of the air gap;

S5: Determine the motor size:

The method for determining the size of the motor includes: according to the requirements of the actual situation, combined with the loss curve and performance parameters of the motor, to determine the size of the motor that makes the motor efficiency reach the optimum.

Further, the method further includes the following steps: S6: Step S2 is based on the preliminary scheme of the electromagnetic design, selects k groups of stator inner diameter lengths according to the arithmetic progression, selects m groups of air gap lengths according to the arithmetic progression, and redesigns The motor is simulated, and the shaft length of the motor is determined according to the main size formula of the motor when the inner diameter of the motor stator is changed;

S7: Calculate the efficiency of the motor based on the two-dimensional simulation results obtained in step S2.

In step S6, the motor is redesigned to meet product specifications and technical requirements.

It is appropriate that k in step S6 takes 6 to 8 groups, and m takes 2 to 6 in step S6.

计算充水式潜水电机的电机常数，将轴长关于定子内径和电机常数的表达式L＝CmecP/(D12n)带入充水式潜水电机水磨擦损耗公式

得到水磨擦损耗随定子内径和气隙长度变化的表达式，其中：θ是动力粘度、D1为转子外径、L为电机芯线长度、ω为同步角速度；σ是气隙的长度、P为电机的机械功率，Cmec为电机常数。The method for drawing the water friction loss curve of the water-filled submersible motor described in step S3 includes: according to the formula

Calculate the motor constant of the water-filled submersible motor, and bring the expression L=CmecP/(D12n) of the shaft length about the inner diameter of the stator and the motor constant into the water friction loss formula of the water-filled submersible motor

Obtain the expression of the water friction loss as a function of the stator inner diameter and air gap length, where: θ is the dynamic viscosity, D1 is the rotor outer diameter, L is the motor core wire length, ω is the synchronous angular velocity; σ is the air gap length, P is the motor The mechanical power, Cmec is the motor constant.

The beneficial effects of the present invention are as follows: (1) The motor design is no longer dependent on the empirical method, and a design method of a water-filled submersible motor is studied, which can select the main size of the motor more accurately.

(2) A design method suitable for optimizing the efficiency of a water-filled submersible motor is provided, so as to reduce the water friction loss of the water-filled submersible motor and improve the motor efficiency.

The method is simple to implement, has obvious effect of improving efficiency, and has wide versatility.

Description of drawings

The accompanying drawings that constitute a part of the present application are used to provide further understanding of the present application, and the schematic embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation of the present application.

Fig. 1 is the flow chart of the design method of water-filled submersible motor efficiency optimization;

Figure 2 is a two-dimensional time-harmonic field simulation diagram when the inner diameter of the stator is 225mm;

Fig. 3 is the curve that water friction loss changes with stator inner diameter in the embodiment;

Fig. 4 is the curve that water friction loss changes with air gap length in the embodiment;

Fig. 5 is the curve that the electrical loss curve changes with the length of the air gap in the embodiment;

Fig. 6 is the curve that the motor loss changes with the stator inner diameter in the embodiment;

FIG. 7 is a graph of motor loss as a function of air gap length in an embodiment.

Detailed ways:

In one embodiment, the YQ55 type wet submersible motor is taken as the research object, the rated voltage of the motor is 380V, 4 poles, and the rated output power is 55kW:

S1: According to the product specifications and technical requirements of the water-filled submersible motor, the preliminary scheme for the electromagnetic design of the water-filled submersible motor is given, including;

S11, according to the technical parameters of the motor and the actual working conditions, the three circles of the motor are selected as 400/225/85mm, and the shaft length is 180mm;

S12, select the silicon steel sheet with the grade of DW540_50 as the material of the motor core, and select copper as the material of the winding and the bar.

S13, the stator adopts trapezoidal slot, and the rotor adopts rectangular slot. In order to reduce the water friction loss, both the stator and the rotor adopt closed slot.

S2: Establish a two-dimensional time-harmonic field simulation model of a water-filled submersible motor as shown in Figure 2. The figure shows the stator and rotor slot fit, slot shape and size:

The method for establishing a two-dimensional time-harmonic field simulation model of a water-filled submersible motor includes: taking the preliminary scheme of electromagnetic design as a benchmark, selecting 7 groups of stator inner diameter lengths according to the arithmetic progression, and selecting 4 groups of gas according to the arithmetic progression. Gap length, redesign the motor, input the motor size and material properties of each part into the simulation software Flux, obtain a two-dimensional model, mesh the two-dimensional model, and perform time-harmonic field simulation on the two-dimensional model. The results of the simulation calculations are shown in the table. 1 and 2 are shown;

Table 1 Preparation data

Table 2 Preparation data

Air gap length (mm) Stator copper loss (W) Rotor copper loss (W) Stator iron loss (W) 1 2077.32 1435.64 776.251 1.5 2267.75 1468.59 762.823 2 2476.94 1509.46 749.932 2.5 2697.35 1549.04 735.63

S3: Draw the water friction loss curve of the water-filled submersible motor:

计算充水式潜水电机的电机常数，将轴长关于定子内径和电机常数的表达式L＝CmecP/(D12n)带入充水式潜水电机水磨擦损耗公式

得到水磨擦损耗随定子内径和气隙长度变化的表达式，根据充水式潜水电机水磨擦损耗的公式，分别绘出水磨擦损耗随定子内径和气隙长度的曲线，其中：θ是动力粘度D1为转子外径；L为电机芯线长度；ω为同步角速度；σ是气隙的长度、P为电机的机械功率，Cmec为电机常数，具体水摩擦损耗曲线详见图3-4。Specifically, according to the formula

Calculate the motor constant of the water-filled submersible motor, and bring the expression L=CmecP/(D12n) of the shaft length about the inner diameter of the stator and the motor constant into the water friction loss formula of the water-filled submersible motor

Obtain the expression of water friction loss with stator inner diameter and air gap length. According to the formula of water friction loss of water-filled submersible motor, draw the curve of water friction loss with stator inner diameter and air gap length, where: θ is the dynamic viscosity D1 is the rotor Outer diameter; L is the length of the motor core wire; ω is the synchronous angular velocity; σ is the length of the air gap, P is the mechanical power of the motor, and Cmec is the motor constant. The specific water friction loss curve is shown in Figure 3-4.

S4: Fitting the loss curve of the water-filled submersible motor:

The method for fitting the loss curve of the water-filled submersible motor includes: according to the simulation result obtained in step S2, it can be seen that when the inner diameter of the motor stator changes, the stator and rotor copper losses and the stator iron loss of the motor hardly change, It can be approximated as a constant value, so it is only necessary to use the least squares method to use the air gap length as the independent variable and the electrical loss as the dependent variable, and the fitting curve of the electrical loss curve with the air gap length is shown in Figure 5. Add the curves with the inner diameter of the stator and the length of the air gap, as shown in Figure 6-7 to obtain the curve of the motor loss changing with the inner diameter of the stator and the length of the air gap;

S5: Determine the motor size:

The method for determining the size of the motor includes: the value range of the diameter-axis-length ratio of the motor is 0.7-1.3. In this example, the diameter-axis-length ratio is selected as 1.22. At this time, the inner diameter of the stator of the motor is 195mm, the shaft length is 239mm, and the gas The gap length is 2mm.

Based on the method of step S2, a two-dimensional time-harmonic field simulation of the motor is performed, and the copper loss of the stator obtained by the simulation is 2300W, the copper loss of the rotor is 1400W, and the iron loss of the stator is 710W.

Taking the size of the motor into the formula of the water friction loss of the submersible motor, the water friction loss of the optimized motor is calculated to be 953W.

The efficiency of the motor is calculated to be 88.6% from the obtained results.

An embodiment of the present invention provides a design method suitable for optimizing the efficiency of a water-filled submersible motor. The method adopts Flux finite element analysis combined with Matlab fitting function to improve the motor efficiency, and calculates the loss of each part of the motor through Flux, and the Performance parameters, Matlab fits the change of the loss of each part of the motor with the inner diameter of the stator and the length of the air gap, and combines the actual situation to determine the size of the motor. Compared with the initial plan, the efficiency of the motor is increased by 1.5%, which guides the optimal design of the motor. significance.

Claims (4)

1. A design method suitable for optimizing efficiency of a water-filled submersible motor is characterized by comprising the following steps: the method comprises the following steps:

s1: providing a preliminary scheme of the electromagnetic design of the water-filled submersible motor according to the product specification and the technical requirement of the water-filled submersible motor;

s2: establishing a two-dimensional time-harmonic field simulation model of the water-filled submersible motor:

the method for establishing the two-dimensional time-harmonic field simulation model of the water-filled submersible motor comprises the following steps: inputting the size of the motor and the material characteristics of each part into simulation software to obtain a two-dimensional model, carrying out grid division on the two-dimensional model in the simulation software, and carrying out two-dimensional time harmonic field electromagnetic simulation on the two-dimensional model;

s3: drawing a water friction loss curve of the water-filled submersible motor:

the method for drawing the water friction loss curve of the water-filled submersible motor comprises the following steps: respectively drawing the change curves of water friction loss along with the inner diameter of the stator and the length of the air gap according to a formula of the water friction loss of the water-filled submersible motor;

according to the formula

Calculating the motor constant of the water-filled submersible motor, and substituting the expression L of the shaft length relative to the inner diameter of the stator and the motor constant, namely CmecP/(D12n), into the formula of the water friction loss of the water-filled submersible motor

Obtaining an expression of water friction loss as a function of stator inner diameter and air gap length, wherein: theta is dynamic viscosity, D1 is the outer diameter of the rotor, L is the length of the core wire of the motor, omega is synchronous angular velocity, sigma is the length of the air gap, P is the mechanical power of the motor, Cmec is the motor constant, and n is the rotating speed;

s4: fitting a loss curve q of the water-filled submersible motor:

the method for fitting the loss curve of the water-filled submersible motor comprises the following steps: fitting an electrical loss curve by a least square method according to the simulation result obtained in the step S2, and adding the change curve of the electrical loss along with the inner diameter of the stator and the length of the air gap to the change curve of the water friction loss of the water-filled submersible motor along with the inner diameter of the stator and the length of the air gap respectively to obtain the change curve of the motor loss along with the inner diameter of the stator and the length of the air gap;

s5: determining the size of the motor:

the method for determining the size of the motor comprises the following steps: and determining the motor size which enables the motor efficiency to reach the optimal value according to the requirements of actual conditions and the loss curve of the motor.

2. The design method for optimizing efficiency of a water-filled submersible motor according to claim 1, characterized in that: further comprising the steps of:

s6: step S2, based on the preliminary scheme of electromagnetic design, selecting the length of the inner diameter of k groups of stators by decreasing according to an arithmetic progression, selecting the length of m groups of air gaps by increasing according to an arithmetic progression, redesigning the motor for simulation, and determining the axial length of the motor according to a motor size formula when the inner diameter of the stator of the motor is changed;

s7: based on the two-dimensional simulation result obtained in step S2, the efficiency of the motor is calculated.

3. The design method for optimizing efficiency of a water-filled submersible motor according to claim 2, characterized in that: in step S6, the motor is redesigned to meet the product specification and technical requirements.

4. The design method for optimizing efficiency of a water-filled submersible motor according to claim 2, characterized in that: in step S6, k is 6-8, and m is 2-6 in step S6.

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