CN110429893B - Motor controller carrier frequency dynamic optimization method and motor controller - Google Patents

Abstract

The invention relates to a dynamic optimization method for carrier frequency of a motor controller, which comprises the following steps: step S1: establishing a motor controller carrier frequency dynamic optimization model of which the target function is related to the motor rotating speed, the motor torque and the motor controller carrier frequency and the constraint condition is related to the motor controller carrier frequency and the sampling frequency; step S2: and solving the dynamic optimization model of the carrier frequency of the motor controller by using a fuzzy logic method to obtain the dynamic optimization carrier frequency of the motor controller. Compared with the prior art, the loss of the motor controller can be reduced by dynamically changing the carrier frequency under the condition of ensuring the harmonic distortion rate.

Description

Motor controller carrier frequency dynamic optimization method and motor controller

Technical Field

The invention relates to the field of power electronics and power transmission, in particular to a dynamic carrier frequency optimization method for a motor controller and the motor controller.

Background

Since the development of electric vehicles is started early in japan and developed countries in europe and the united states, they have spent much effort and time on the research and development of motor controllers. Many automobile electronic product manufacturers, such as the german continent group and the bosch group, have also started the development of motor controllers. Some automobile parts or automobile developers, FEV engine technologies ltd, germany, licardama, etc., have not yet ignored status in the field of electric automobiles. As developed countries such as Europe and America develop electric vehicles early in starting time, the developed countries have quite abundant electric vehicle development experiences, and the control strategies of the developed countries have quite high systematicness and are also quite beyond the efficiency control of a controller. And their automobile manufacturers and some automobile part manufacturers, even some electronic device providers, have together promoted the open system architecture of the car, offer the more simple and direct way for the use of development environment and electronic control unit afterwards, let the development of the controller tend to the labeling more.

In developed countries in recent years, a permanent magnet synchronous motor controller is adopted in manufacturing and research of electric automobiles in japan, and most electric automobile developers in china also adopt the permanent magnet synchronous motor controller and a matched controller, the power controlled by the motor controller can reach about 130 kw, the electric automobile has a large constant power operation range, and the rotating speed can reach 4.7 times of a rated value. Compared with japan, the control technology and control strategy in europe and the united states are well-established, but most of them adopt an asynchronous motor controller as a direct power source, and compared with the tesla company in the united states, all of them adopt an asynchronous motor controller, and the controller performance is also excellent.

The motor controller comprises an inverter, the inverter comprises an IGBT (insulated gate bipolar transistor), the power loss of the IGBT is related to the carrier frequency, and the power loss is increased along with the increase of the carrier frequency, so that the efficiency is reduced, the heating of the power module is increased, the operation is not favorable, and the power loss is increased along with the increase of the carrier frequency. The larger the carrier frequency, the larger the loss of the inverter and the smaller the output power. If the environmental temperature is high, the dead zone of the upper inverter tube and the lower inverter tube of the inverter bridge in the alternate conduction process becomes small, and the bridge arm can be short-circuited to damage the inverter when the dead zone is serious. The carrier frequency also affects the amount of output total harmonic distortion and motor noise.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a motor controller carrier frequency dynamic optimization method and a motor controller.

The purpose of the invention can be realized by the following technical scheme:

a method for dynamically optimizing carrier frequency of a motor controller comprises the following steps:

step S1: establishing a motor controller carrier frequency dynamic optimization model of which the target function is related to the motor rotating speed, the motor torque and the motor controller carrier frequency and the constraint condition is related to the motor controller carrier frequency and the sampling frequency;

step S2: and solving the dynamic optimization model of the carrier frequency of the motor controller by using a fuzzy logic method to obtain the dynamic optimization carrier frequency of the motor controller.

Solving the objective function of step S1 includes the following steps:

step S11: obtaining system conversion efficiency according to the motor parameters and the inverter loss;

step S12: and obtaining an objective function related to the motor rotating speed, the motor torque and the motor controller carrier frequency according to the torque formula and the system conversion efficiency.

The system conversion efficiency is as follows:

η＝P_{output of the motor}/(P_{Output of the motor}+P_{Loss of motor}+P_IGBT)

Where eta is the system conversion efficiency, P_IGBTFor inverter losses, P_{Loss of motor}Is lost to the motor controller including iron and copper losses.

Said P_IGBTComprises the following steps:

P_IGBT＝kf_C

wherein k is a constant, f_CIs the carrier frequency.

The objective function is as follows:

η(f_C)＝(T·n)/(T·n+9550·(P_IGBT+P_{loss of motor}))

Wherein T is the motor torque, and n is the motor rotation speed.

The constraint conditions are as follows:

f_S＝3Kf_C

f_min≤f_C≤f_max

wherein K is an integer, f_CIs a carrier frequency, f_STo sample frequency, f_minAnd f_maxThe motor controller limit operating frequency.

The fuzzy logic method is a Mamdani fuzzy inference method.

The fuzzy logic method adopts a gravity center method to solve.

A motor controller utilizes the carrier frequency dynamic optimization method of the motor controller to carry out carrier frequency dynamic control.

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

(1) the dynamic carrier frequency optimization model of the motor controller can dynamically change the carrier frequency under the condition of ensuring the harmonic distortion rate, and the loss of the motor controller is reduced.

(2) The real-time dynamic carrier frequency can be obtained according to the running working condition of the electric automobile, namely by detecting the change of the rotating speed and the torque of the electric automobile.

(3) The dynamic carrier frequency is calculated by a fuzzy logic method, and the language control rule is easy to establish and has strong robustness based on qualitative recognition of an industrial process.

(4) The fuzzy logic method adopts a gravity center method to solve, has high calculation speed and can quickly find the optimal position.

Drawings

FIG. 1 is a flow chart of the present invention.

Detailed Description

The invention is described in detail below with reference to the figures and specific embodiments. The present embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation manner and a specific operation process are given, but the scope of the present invention is not limited to the following embodiments.

Examples

In this embodiment, a carrier frequency dynamic optimization model of the motor controller is established, and the model is optimized through theoretical calculation under the condition that THD (harmonic distortion) meets requirements, so that the efficiency of the system changing along with the output power and the carrier frequency of the motor is optimal, and thus the dynamic carrier optimization frequency is obtained. By using the dynamic carrier frequency technology, especially when the requirement on the carrier frequency is not high at low rotating speed, the loss of the motor controller can be effectively reduced by adjusting the carrier frequency, the efficiency of the motor controller is improved, and the endurance mileage of about 1.5 kilometers can be preliminarily estimated to be improved every 100 kilometers.

(1) Carrier frequency dynamic optimization model of motor controller

And optimizing an efficiency model of the system, and constructing a motor controller carrier frequency dynamic optimization model.

1.1 System efficiency modeling

The motor parameters and the inverter are considered as an integral system consideration. Obtaining the energy conversion efficiency of the system:

η＝P_{output of the motor}/(P_{Output of the motor}+P_{Loss of motor}+P_IGBT) (1-1)

In the formula: where eta is the system conversion efficiency, P_IGBTFor inverter losses, P_{Loss of motor}To compriseIron and copper losses.

P_IGBTIn relation to the carrier frequency:

P_IGBT＝kf_C

wherein f is_CIs the carrier frequency.

In essence eta is related to the carrier frequency f_CAs a function of (c).

And the torque formula:

T＝9550P/n (1-2)

wherein T is the torque of the motor, n is the rotating speed of the motor, and P is the output power of the motor.

Substituting equation (1-2) into (1-1) may result in an objective function related to motor speed, torque, and carrier frequency:

η(f_C)＝(T·n)/(T·n+9550·(P_IGBT+P_{loss of motor})) (1-3)

1.2 constraint conditions

1) The carrier frequency affects not only the efficiency of the output but also the thd. Therefore, we have to optimize the thd while optimizing the objective function. The bipolar SVPWM (space vector pulse width modulation) is modeled next:

setting THD constraints, i.e.

f_S＝3Kf_C (1-4)

f_SIs f_CAnd an integral multiple of 3 is the smallest harmonic component.

2) The switching devices also have upper and lower limits on the carrier frequency, i.e.

f_min≤f_C≤f_max (1-5)

Wherein K is an integer, f_STo sample frequency, f_minAnd f_maxThe motor controller limit operating frequency.

1.3 optimization Algorithm

The total harmonic distortion rate and the carrier frequency f can be obtained by analyzing a carrier frequency dynamic optimization model of the motor controller_CA negative correlation is present, i.e. the higher the carrier frequency, the smaller the harmonic content.

Defining variables: the fuzzy logic controller includes two input variables and one output variable. The input includes motor torque and speed, and the output is carrier frequency. The synthetic inference algorithm adopts Mamdani inference, three preconditions are used as minimization factors, a conclusion part is used as maximization factors, and the solution fuzzy adopts a center of gravity method (COA). The input and output universe is T ═ { LE ME GE }; n ═ { LE ME GE }; FSW ═ PS LE ME GE }. The output carrier frequency member function is Positive Small (PS), small (LE, Little), medium (ME, Middle), large (GE, Great).

Table 1 is a fuzzy rule table:

table 1 control rules table

The prior art basically adopts vector control and direct torque control, and essentially changes the modulation wave of PWM. The embodiment adopts continuous modulation to change the carrier wave of PWM aiming at the running condition of the electric automobile, and the starting point of the technology is to reduce the loss of a motor controller, and the harmonic wave also meets the requirement under certain constraint conditions.

According to the embodiment, the carrier frequency is continuously optimized by adopting fuzzy control according to the running condition of the electric automobile, namely continuous modulation is adopted, and the carrier frequency is dynamically changed to reduce the loss of the motor controller. At high torque, the carrier frequency is reduced at low rotation speed, so that the loss of the motor controller can be reduced.

The embodiment can be applied to the electric automobile industry and can also be applied to the motion control occasion with large load change.

Claims (2)

1. A dynamic optimization method for carrier frequency of a motor controller is characterized by comprising the following steps:

step S1: establishing a motor controller carrier frequency dynamic optimization model of which the target function is related to the motor rotating speed, the motor torque and the motor controller carrier frequency and the constraint condition is related to the motor controller carrier frequency and the sampling frequency;

step S2: solving a motor controller carrier frequency dynamic optimization model by using a fuzzy logic method to obtain a motor controller dynamic optimization carrier frequency;

the solving process of the fuzzy logic method comprises the following steps:

defining variables: the fuzzy logic controller comprises two input variables and an output variable; the input comprises motor torque and rotating speed, and the output is carrier frequency; the synthetic inference algorithm adopts Mamdani inference, three preconditions are used as minimization factors, a conclusion part is used as maximization factors, and the solution fuzzy adopts a gravity center method (COA); the input and output universe is T ═ { LE ME GE }; n ═ { LE ME GE }; FSW ═ { PS LE ME GE }; the output carrier frequency membership functions are Positive Small (PS), small (LE, Little), medium (ME, Middle) and large (GE, Great);

table 1 is a fuzzy rule table:

TABLE 1 fuzzy rule Table

Solving the objective function of step S1 includes the following steps:

step S11: obtaining system conversion efficiency according to the motor parameters and the inverter loss;

step S12: obtaining a target function related to the rotating speed and the torque of the motor and the carrier frequency of the motor controller according to a torque formula and the system conversion efficiency;

the system conversion efficiency is as follows:

η＝P_{output of the motor}/(P_{Output of the motor}+P_{Loss of motor}+P_IGBT)

Where eta is the system conversion efficiency, P_IGBTFor inverter losses, P_{Loss of motor}Losses for the motor controller including iron and copper losses;

said P_IGBTComprises the following steps:

P_IGBT＝kf_C

wherein k is a constant, f_CIs the carrier frequency;

the objective function is as follows:

η(f_C)＝(T·n)/(T·n+9550·(P_IGBT+P_{loss of motor}))

Wherein T is motor torque, and n is motor rotating speed;

the constraint conditions are as follows:

f_S＝3Kf_C

f_min≤f_C≤f_max

wherein K is an integer, f_CIs a carrier frequency, f_STo sample frequency, f_minAnd f_maxThe motor controller limit operating frequency.

2. A motor controller, characterized in that, the carrier frequency dynamic control is performed by using the motor controller carrier frequency dynamic optimization method of claim 1.

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