CN102566434A - Motor thermodynamic model-based over-temperature protection method for electric power-assisted steering system - Google Patents

Abstract

The invention provides a motor thermodynamic model-based over-temperature protection method for an electric power-assisted steering system. The method comprises the following steps of: establishing a motor thermodynamic model which represents a relationship between heat which is generated and dissipated during operation of a motor and the temperature of the motor; sampling the current of the motor and the temperature of a control module; calculating the current estimation temperature of the motor by using the current of the motor, the temperature of the control module and the motor thermodynamic model; comparing the calculated estimation temperature of the motor with the range of a normal operation temperature threshold value of the motor; and limiting the current of the motor if the estimation temperature of the motor is not in the range of the temperature threshold value. The method has the advantages of low implementation cost, simple technology and high accuracy.

Description

Electric boosting steering system is used the excess temperature protection method based on the motor heat mechanical model

Technical field

The present invention relates to a kind of diagnostic method of motor, particularly a kind of electric boosting steering system is used the excess temperature protection method based on the motor heat mechanical model.

Background technology

Electric boosting steering system has simple in structure, plurality of advantages such as power-assisted ability good, the saving energy than traditional hydraulic power-assist steering system.One of core component of electric boosting steering system is exactly a motor, and whether closely bound up with the security performance of steering the operate as normal of these parts is.So, the diagnostic method that the emphasis of electric boosting steering system exploitation and difficult point are exactly motor, wherein one of motor overheat protector most important diagnostic method of being.

The conventional electric-powered servo steering system is used the motor excess temperature protection method, adopts dual mode to obtain the temperature of motor usually: the one, through adding the temperature that temperature sensor obtains motor at motor body; The 2nd, with the temperature of the control module of controlling the motor running, carry out excess temperature as the temperature of motor and judge.

But, more than two kinds of methods all have drawback, first method, adding temperature sensor at this machine of motor can increase extra cost, and temperature sensor needs the support of PCB circuit, adding the PCB circuit at motor body can increase technical difficulty.Second method because the different environment temperatures that cause with the installation site of motor on vehicle of control module are different, and the thermal power coefficient of the thermal power coefficient of control module and motor also difference is bigger.

In sum, the prior electric servo steering system with the motor excess temperature protection method exist cost high, realize that difficulty is big, the perhaps inaccurate problem of temperature survey.

Summary of the invention

The purpose of this invention is to provide a kind of electric boosting steering system and use excess temperature protection method based on the motor heat mechanical model; There is the cost height, realizes that difficulty is big with the motor excess temperature protection method to solve the prior electric servo steering system, perhaps the inaccurate problem of temperature survey.

The present invention proposes a kind of electric boosting steering system and uses the excess temperature protection method based on the motor heat mechanical model, may further comprise the steps:

Set up a motor heat mechanical model, the relation between the heat that this motor heat mechanical model produces when representing machine operation, the heat that distributes and the motor temperature;

Sampling current of electric and control module temperature;

Utilize current of electric, control module temperature and motor heat mechanical model, calculate current motor estimated temperature;

The temperature threshold scope of motor estimated temperature that calculates and motor operate as normal is compared;

If the motor estimated temperature not in the scope of temperature threshold, then limits the electric current of motor.

Further, this motor heat mechanical model is:,

T _MTE＝ΔT′+T _ECU

$\mathrm{\Δ}{T}^{\′}=\mathrm{\ΔT}+\frac{(I^2*R-(\mathrm{\ΔT}/{\mathrm{\θ}}_{\mathrm{cool}}))*\mathrm{\Δt}}{C_{\mathrm{motor}}}$

Wherein, T _MTEBe motor estimated temperature, T _ECUBe the temperature of control module, Δ T ' is the temperature variation of current time motor, and Δ T is the temperature variation of last time motor, and I is a current of electric, and R is a motor resistance, θ _CoolBe the motor cooling ratio, Δ t is temperature computation interval time, C _MotorBe the motor heat capacity.

With respect to prior art; The invention has the beneficial effects as follows: come the motor of electric boosting steering system is carried out overheat protector through the inventive method; Implementation cost is low, technology is simple; And considered in the calculating process that the present invention adopts that motor heat power and environment to the influence that motor temperature produces, make the motor estimated temperature that calculates more near the real temperature of motor, made diagnosis more accurate.

Description of drawings

Fig. 1 uses a kind of embodiment process flow diagram based on the excess temperature protection method of motor heat mechanical model for electric boosting steering system of the present invention.

Embodiment

Main thought of the present invention is that the temperature with control module is the basis; And combine the thermal power and the influence of environment of motor to the temperature variation generation; Estimate the temperature of motor, thereby reflected the temperature that motor is current more accurately, improved accuracy the motor overheat protector.

Specify the present invention below in conjunction with accompanying drawing, see also Fig. 1, it uses a kind of embodiment process flow diagram based on the excess temperature protection method of motor heat mechanical model for electric boosting steering system of the present invention, and it may further comprise the steps:

S1 sets up a motor heat mechanical model, the relation between the heat that this motor heat mechanical model produces when representing machine operation, the heat that distributes and the motor temperature.

The mathematical formulae of motor heat mechanical model is:

T _MTE＝ΔT′+T _ECU

$\mathrm{\Δ}{T}^{\′}=\mathrm{\ΔT}+\frac{(I^2*R-(\mathrm{\ΔT}/{\mathrm{\θ}}_{\mathrm{cool}}))*\mathrm{\Δt}}{C_{\mathrm{motor}}}$

Formula symbol definition such as table 1:

Title	Explanation	Unit
			T MTE	The motor estimated temperature	℃
T ECU	The temperature of control module	℃
			ΔT′	The temperature variation of current time motor	℃
ΔT	The temperature variation of last time motor	℃
			I	Current of electric	A
R	Motor resistance	Ohm
			θ cool	The motor cooling ratio	℃/W
Δt	Temperature computation interval time	s
			C motor	The motor heat capacity	J/℃

Table 1

Wherein, I ²R* Δ t is illustrated in the heat that machine operation produces among the time Δ t; Δ T/ θ _Cool* Δ t is illustrated in the heat that the motor cooling is distributed among the time Δ t; Then,

Just be illustrated in the variable quantity of motor temperature among the time Δ t.

S2, sampling current of electric and control module temperature.

Before the motor heat mechanical model begins to calculate, need to gather the temperature of current of electric and control module, coming provides input signal for the true(-)running of motor heat mechanical model.Current of electric and control module temperature can be gathered by control module; Control module of the present invention; Be ECU (ElectronicControl Unit, electronic control unit), claim " car running computer ", " vehicle-mounted computer " etc. again; Say it is the automobile microcomputerized controller from purposes, also be the automobile single-chip microcomputer.It not only can gather current of electric, and carries temperature sensor, thereby the temperature of collection easily itself.

S3 utilizes current of electric, control module temperature and motor heat mechanical model, calculates current motor estimated temperature.

When utilizing the motor heat mechanical model to calculate, motor resistance R, motor cooling ratio θ in the formula _Cool, the motor heat capacity C _MotorIt all is the parameter of motor; Temperature computation Δ interval time t is a setting value, can adjust according to actual needs, and t is more little for Δ, and then the precision to motor diagnostic is high more; The temperature T of current of electric I and control module _ECUBe the sampled value of step S2, this shows that this motor heat mechanical model considered that motor heat power and environment to the influence that motor temperature produces, make the motor estimated temperature T that calculates _MTEMore, make overheat protector more accurate near the real temperature of motor.

And, because the motor estimated temperature is to obtain through the control module temperature estimation, thereby need not in motor, to add in addition temperature sensor and PCB circuit board, also reduced technical difficulty when practicing thrift cost.

S4 compares the temperature threshold scope of motor estimated temperature that calculates and motor operate as normal.

S5 is if the motor estimated temperature not in the scope of temperature threshold, then limits the electric current of motor.

Can the lowest temperature Tmin and the upper limit Tmax of the motor operate as normal of motor estimated temperature that obtains among the step S3 and setting be compared; If the motor estimated temperature is lower than lower limit Tmin or is higher than upper limit Tmax; Then limit current of electric and be output as I_limit, wherein I_limit can set according to motor model or actual needs.

More than disclosedly be merely a specific embodiment of the present invention, but the present invention is not limited thereto, any those skilled in the art can think variation, only otherwise exceed the said scope of appended claims, all should drop in protection scope of the present invention.

Claims (2)

1. an electric boosting steering system is used the excess temperature protection method based on the motor heat mechanical model, it is characterized in that, may further comprise the steps:

Set up a motor heat mechanical model, the relation between the heat that this motor heat mechanical model produces when representing machine operation, the heat that distributes and the motor temperature;

Sampling current of electric and control module temperature;

Utilize current of electric, control module temperature and motor heat mechanical model, calculate current motor estimated temperature;

The temperature threshold scope of motor estimated temperature that calculates and motor operate as normal is compared;

If the motor estimated temperature not in the scope of temperature threshold, then limits the electric current of motor.

2. electric boosting steering system as claimed in claim 1 is used the excess temperature protection method based on the motor heat mechanical model, it is characterized in that, this motor heat mechanical model is:,

T _MTE＝ΔT′+T _ECU

$\mathrm{\Δ}{T}^{\′}=\mathrm{\ΔT}+\frac{(I^2*R-(\mathrm{\ΔT}/{\mathrm{\θ}}_{\mathrm{cool}}))*\mathrm{\Δt}}{C_{\mathrm{motor}}}$

Wherein, T _MTEBe motor estimated temperature, T _ECUBe the temperature of control module, Δ T ' is the temperature variation of current time motor, and Δ T is the temperature variation of last time motor, and I is a current of electric, and R is a motor resistance, θ _CoolBe the motor cooling ratio, Δ t is temperature computation interval time, C _MotorBe the motor heat capacity.

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