CN105676001A - Equivalent inductance measurement method of proportional solenoid valve and oil pressure control method - Google Patents

Abstract

The invention provides an equivalent inductance measurement method of a proportional solenoid valve and an oil pressure control method. The equivalent inductance measurement method can avoid temperature measurement, directly uses a collected current curve of the proportional solenoid valve to obtain a relation function of inductance, and accurately measures the equivalent inductance of the proportional solenoid valve during a control process. For noise removal processing of the current curve, the equivalent inductance measurement method can ensure validity of the collected current curve, eliminate a deviation part of an inductance function, and improve the accuracy of the equivalent inductance of the proportional solenoid valve. The oil pressure control method does not need to use any temperature sensor to calibrate the influence of the oil temperature on the oil pressure output by the solenoid valve, and changes of the oil temperature are reflected by changes of the equivalent inductance of the proportional solenoid valve. The oil pressure output by the proportional solenoid valve is controlled accurately by the equivalent inductance measured by the equivalent inductance measurement method and the input current, so that an oil pressure control structure and the work load of temperature sensor calibration can be simplified.

Description

The equivalent inductance measuring method of proportional solenoid and hydraulic control method

Technical field

The present invention relates to the control field of proportional solenoid, particularly relate to equivalent inductance measuring method and the hydraulic control method of a kind of proportional solenoid.

Background technology

Hydraulic proportional electromagnetic valve is the key element of heavy vehicle shifting and variable speed control system and other hydraulic systems. The whether accurate gearshift stationarity to speed change system of proportional solenoid output pressure and comfortableness have a significant impact. When the oil temperature of speed change system very big change does not occur, proportional solenoid output oil pressure P and its input current I is the functional relationship determined, its control accuracy is also easy to get guarantee. But in practice, the oil temperature of speed change system is sizable variations in temperature inevitably, cause that the input/output relation of proportional solenoid changes, thus affecting gearshift performance. The counter-measure adopted in the past is in conjunction with temperature sensor, calibrating proportional solenoid input-output function relation under each temperature spot, and based on this under different temperature points, output oil pressure P corresponding for comparative example electromagnetic valve input current I is predicted. Although the method can substantially meet needs, but each proportional solenoid is demarcated, workload is huge, and calibration process needs temperature sensor.

The impact of shifting system oil temperature comparative example electromagnetic valve output oil pressure P, is mainly reflected in the output electromagnetic force of key element proportion electro-magnet of comparative example electromagnetic valve. The size of the output oil pressure P of proportioning valve is determined by input electromagnetic force size. And according to effective air gap magnetic conductance method, electromagnetic force size is by the input current I and equivalent inductance L of proportion electro-magnet_dThe impact of two factors. When system oil temperature is constant, equivalent inductance L_dAlso constant. So the size of proportional solenoid output oil pressure P is solely dependent upon the size of input current I in this case. And when system oil temperature changes greatly, equivalent inductance L_dSize also change therewith, here it is the reason that proportioning valve input/output relation changes.

The reason why not drawn attention before proportional solenoid equivalent inductance On-line Measuring Method is in that, compared to equivalent resistance R, equivalent inductance L_dMeasurement much more difficult. Equivalent inductance L_dMeasurement need first to try to achieve the time constant of equivalent circuit, the where the shoe pinches that correct time constant is measured is in that to need considerable data point to be fitted ensureing precision, and to overcome the impact of counter electromotive force. Equivalent inductance L_dThe where the shoe pinches measured also resides in, and inductance is the binary function about temperature and electric current I, even if at the same temperature, changes as well as the change of electric current I. Find out the equivalent inductance L determining proportion electro-magnet output electromagnetic force_d, it is also desirable to certain analysis and disposal skill.

Summary of the invention

In view of Problems existing in background technology, it is an object of the invention to provide the equivalent inductance measuring method of a kind of proportional solenoid and hydraulic control method, it can accurately measure the equivalent inductance of proportional solenoid in control process, and just can control the output oil pressure of proportional solenoid accurately according to the equivalent inductance obtained without using temperature sensor.

To achieve these goals, in first aspect, the invention provides the equivalent inductance measuring method of a kind of proportional solenoid, it includes step 1 to step 5.

Step 1: comparative example electromagnetic valve input pwm signal, and utilize the data point of voltage signal that data collecting module collected input and the data point of the current signal of correspondence, and then obtain steady-state current voltage waveform; Wherein the frequency of pwm signal is fHz, dutycycle D%, and the voltage magnitude of pwm signal is E; The sample frequency of data acquisition module is FHz, within a cycle of pwm signal, and the number of data points of the number of data points of the voltage signal of collection and corresponding current signal:

$n=\frac{F\×D\%}{f};$

The voltage signal in c the cycle of output of pwm signal, the total number of data points collected is c n.

Step 2: the extracting data current curve from gathering: the voltage of pwm signal input only has two states of 0V and E, if voltage is t from the 0V time point jumping to E₁, voltage is t from the E time point jumping to 0V₂, then at t₁～t₂Time period in current signal be propradation, the current curve obtained is ascending curve; In the data point gathered in step 1, the set of all trip points that voltage jumps to E from 0V is T₁, the set of all trip points that voltage jumps to 0V from E is T₂, T₁And T₁Acquiring method be:

If Volt_(m+1)-Volt_m>E₁, then T₁(k)=t_m;

If Volt_(m+1)-Volt_m<-E₁, then T₂(k)=t_m;

Wherein, t_mRepresent the moment of m point, Volt_mRepresent the magnitude of voltage of m point, and k ∈ (0, m), E₁=0.8E.

If T₂(1)<T₁(1), then T is removed₂(1) corresponding current signal data point; If T₁Number of data points compare T₂Many one of number of data points, then remove T₁The data point of current signal of last correspondence, it is ensured that T₂(1)>T₁(1) and the number of data points of the current signal of correspondence identical; So at arbitrary time period T₁(k)～T₂The k current curve that current curve is kth section that () is corresponding, the current function that this current curve is corresponding is I (k), thus can extract all current curves corresponding to the data point of collection and current function.

Step 3: carry out all current curves obtained eliminating noise processed: for pwm signal when the interval of j adjacent current curve is within 2 j, it is considered as electrical characteristic parameter to be not changed in, this j current curve is processed by following formula sum-average arithmetic, to reach to eliminate the effect of noise:

$I_0\left(k\right)=\frac{1}{j}\underset{i=1}{\overset{j}{\&Sigma;}}I\left(k\right)$

Wherein, I₀K () is the current function after elimination noise, I (k) is the kth section current function intercepted.

Step 4: the current curve after eliminating noise is carried out polynomial curve fitting, obtains inductance change curve. Because proportion electro-magnet circuit can regard single order resistance-inductance series circuit as, with common firstorder circuit the difference is that, its inductance is a variable, say, that the time constant of system is not constant, in this case, it is impossible to be fitted with simple exponential type function.

Average current in proportion electro-magnet circuit is that I, I are by the current function I after all elimination noises collected₀K the electric current sum-average arithmetic in () obtains; Equivalent resistance in proportion electro-magnet circuit is R,

$R=\frac{E*D\%}{I};$

When inductance remains unchanged, the inductance in proportion electro-magnet circuit is L, then curent change relation meets following functional relation:

$i\left(t\right)=\&lsqb;i\left(0\right)-i\left(\mathrm{\&infin;}\right)\&rsqb;*\exp (-\frac{R}{L}t)+i\left(\mathrm{\&infin;}\right);$

Wherein, i (t) is the relation function of electric current i Yu time t, and i (0) is initial current, and i (∞) is saturation current.

When inductance changes, using inductance function L (i) as electric current, the change procedure of electric current i being divided into l section, the inductance in each section of Δ t regards constant L as_p, then in whole process, curent change meets following functional relation:

$i\left(t\right)=\&lsqb;i\left(0\right)-i\left(\mathrm{\&infin;}\right)\&rsqb;*\exp (-\underset{p=0}{\overset{l-1}{\&Sigma;}}\frac{R}{L_p}\mathrm{\&Delta;}t)+i\left(\mathrm{\&infin;}\right);$

When l tends to infinity, the change function of electric current is as follows:

$i\left(t\right)=\&lsqb;i\left(0\right)-i\left(\mathrm{\&infin;}\right)\&rsqb;*\exp (-{\&Integral;}_0^t\frac{R}{L\left(i\right(t))}dt)+i\left(\mathrm{\&infin;}\right);$

Wherein, i (0) is initial current, and i (∞) is saturation current, and i (∞)=I/ (D%);

To above formula derivation, obtain relation function L (t) of inductance t in time:

L (t)=R* (i (∞)-i (t))/(di/dt).

Supplement derivation as follows:

$i\left(t\right)=\&lsqb;i\left(0\right)-i\left(\mathrm{\&infin;}\right)\&rsqb;*\exp (-{\&Integral;}_0^t\frac{R}{L\left(i\right(t))}dt)+i\left(\mathrm{\&infin;}\right)$

$\exp (-{\&Integral;}_0^t\frac{R}{L\left(i\right(t))}dt)=\frac{i\left(t\right)-i\left(\mathrm{\&infin;}\right)}{i\left(0\right)-i\left(\mathrm{\&infin;}\right)}$

$-{\&Integral;}_0^t\frac{R}{L\left(i\right(t))}dt=ln\left(\frac{i\left(t\right)-i\left(\mathrm{\&infin;}\right)}{i\left(0\right)-i\left(\mathrm{\&infin;}\right)}\right)$

$-\frac{R}{L\left(i\right(t))}=\frac{di/dt}{i\left(t\right)-i\left(\mathrm{\&infin;}\right)}$

Obtain: L (t)=R* (i (∞)-i (t))/(di/dt).

Step 5: reject the skew component in inductance function L (t), obtain effective equivalent inductance L_d。

Although the effect that current curve carries out polynomial curve fitting is better, but can there is bigger deviation in the initial and termination phase of current curve, affect the accuracy of result; Reject the initial and termination phase that deviation is bigger, and retain the intermediate change stable interstage, to obtain inductance function L ' (t) revised:

If dL (t)/dt < M, then L ' (t)=L (t), wherein M is the value being manually set according to inductance function L (t) and derivative thereof.

Again inductance function L ' (t) revised is averaged, namely obtains required effective equivalent inductance L_d:

L_d=mean (L ' (t)).

In second aspect, the invention provides a kind of hydraulic control method, it adopts the equivalent inductance measuring method of proportional solenoid of first aspect present invention, and demarcates the output oil pressure P and input current I and equivalent inductance L of described proportional solenoid_dRelation curve P=f (L_d, I), the output oil pressure P of proportional solenoid is then controlled according to comparative example electromagnetic valve input pwm signal.

Beneficial effects of the present invention is as follows:

In the equivalent inductance measuring method of the proportional solenoid according to the present invention, avoid the measurement to temperature, directly utilize relation function L (t) that the current curve of the proportional solenoid of collection obtains the inductance of proportional solenoid, measure the equivalent inductance of proportional solenoid in control process accurately; And the denoising Processing to current curve, it is possible to ensure the effectiveness of the current curve gathered, reject the skew component in inductance function, it is possible to increase the accuracy of the equivalent inductance of proportional solenoid.

According in the hydraulic control method of the present invention, need not utilize temperature sensors for demarcating the oil pressure P impact that electromagnetic valve is exported by oil temperature, and directly by the reacting condition of oil temperature in the change of the equivalent inductance of proportional solenoid, by the equivalent inductance L utilizing the equivalent inductance measuring method of above-mentioned proportional solenoid to measure_dAnd input current I controls the oil pressure P of proportional solenoid output accurately, simplify the structure of oil pressure cntrol and the workload of calibration of sensor.

Accompanying drawing explanation

Fig. 1 is the principle schematic of the equivalent inductance measuring method of the proportional solenoid according to the present invention and hydraulic control method.

Detailed description of the invention

Describe equivalent inductance measuring method and the hydraulic control method of the proportional solenoid of the present invention with reference to the accompanying drawings in detail.

First the equivalent inductance measuring method of proportional solenoid according to a first aspect of the present invention is described.

With reference to Fig. 1, include step 1 to step 5 according to the equivalent inductance measuring method of the proportional solenoid of the present invention.

Step 1: comparative example electromagnetic valve input pwm signal, and utilize the data point of voltage signal that data collecting module collected input and the data point of the current signal of correspondence, and then obtain steady-state current voltage waveform; Wherein the frequency of pwm signal is fHz, dutycycle D%, and the voltage magnitude of pwm signal is E; The sample frequency of data acquisition module is FHz, within a cycle of pwm signal, and the number of data points of the number of data points of the voltage signal of collection and corresponding current signal:

$n=\frac{F\&times;D\%}{f};$

The voltage signal in c the cycle of output of pwm signal, the total number of data points collected is c n.

Step 2: the extracting data current curve from gathering: the voltage of pwm signal input only has two states of 0V and E, if voltage is t from the 0V time point jumping to E₁, voltage is t from the E time point jumping to 0V₂, then at t₁～t₂Time period in current signal be propradation, the current curve obtained is ascending curve; In the data point gathered in step 1, the set of all trip points that voltage jumps to E from 0V is T₁, the set of all trip points that voltage jumps to 0V from E is T₂, T₁And T₁Acquiring method be:

If Volt_(m+1)-Volt_m>E₁, then T₁(k)=t_m;

If Volt_(m+1)-Volt_m<-E₁, then T₂(k)=t_m;

Wherein, t_mRepresent the moment of m point, Volt_mRepresent the magnitude of voltage of m point, and k ∈ (0, m), E₁=0.8E.

If T₂(1)<T₁(1), then T is removed₂(1) corresponding current signal data point; If T₁Number of data points compare T₂Many one of number of data points, then remove T₁The data point of current signal of last correspondence, it is ensured that T₂(1)>T₁(1) and the number of data points of the current signal of correspondence identical; So at arbitrary time period T₁(k)～T₂The k current curve that current curve is kth section that () is corresponding, the current function that this current curve is corresponding is I (k), thus can extract all current curves corresponding to the data point of collection and current function.

Step 3: carry out all current curves obtained eliminating noise processed: for pwm signal when the interval of j adjacent current curve is within 2 j, it is considered as electrical characteristic parameter to be not changed in, this j current curve is processed by following formula sum-average arithmetic, to reach to eliminate the effect of noise:

$I_0\left(k\right)=\frac{1}{j}\underset{i=1}{\overset{j}{\&Sigma;}}I\left(k\right)$

Wherein, I₀K () is the current function after elimination noise, I (k) is the kth section current function intercepted.

Step 4: the current curve after eliminating noise is carried out polynomial curve fitting, obtains inductance change curve. Because proportion electro-magnet circuit can regard single order resistance-inductance series circuit as, with common firstorder circuit the difference is that, its inductance is a variable, say, that the time constant of system is not constant, in this case, it is impossible to be fitted with simple exponential type function.

Average current in proportion electro-magnet circuit is that I, I are by the current function I after all elimination noises collected₀K the electric current sum-average arithmetic in () obtains; Equivalent resistance in proportion electro-magnet circuit is R,

$R=\frac{E*D\%}{I};$

When inductance remains unchanged, the inductance in proportion electro-magnet circuit is L, then curent change relation meets following functional relation:

$i\left(t\right)=\&lsqb;i\left(0\right)-i\left(\mathrm{\&infin;}\right)\&rsqb;*\exp (-\frac{R}{L}t)+i\left(\mathrm{\&infin;}\right);$

Wherein, i (t) is the relation function of electric current i Yu time t, and i (0) is initial current, and i (∞) is saturation current.

When inductance changes, using inductance function L (i) as electric current, the change procedure of electric current i being divided into l section, the inductance in each section of Δ t regards constant L as_p, then in whole process, curent change meets following functional relation:

$i\left(t\right)=\&lsqb;i\left(0\right)-i\left(\mathrm{\&infin;}\right)\&rsqb;*\exp (-\underset{p=0}{\overset{l-1}{\&Sigma;}}\frac{R}{L_p}\mathrm{\&Delta;}t)+i\left(\mathrm{\&infin;}\right);$

When l tends to infinity, the change function of electric current is as follows:

$i\left(t\right)=\&lsqb;i\left(0\right)-i\left(\mathrm{\&infin;}\right)\&rsqb;*\exp (-{\&Integral;}_0^t\frac{R}{L\left(i\right(t))}dt)+i\left(\mathrm{\&infin;}\right);$

Wherein, i (0) is initial current, and i (∞) is saturation current, and i (∞)=I/ (D%);

To above formula derivation, obtain relation function L (t) of inductance t in time:

L (t)=R* (i (∞)-i (t))/(di/dt).

Supplement derivation as follows:

$i\left(t\right)=\&lsqb;i\left(0\right)-i\left(\mathrm{\&infin;}\right)\&rsqb;*\exp (-{\&Integral;}_0^t\frac{R}{L\left(i\right(t))}dt)+i\left(\mathrm{\&infin;}\right)$

$\exp (-{\&Integral;}_0^t\frac{R}{L\left(i\right(t))}dt)=\frac{i\left(t\right)-i\left(\mathrm{\&infin;}\right)}{i\left(0\right)-i\left(\mathrm{\&infin;}\right)}$

$-{\&Integral;}_0^t\frac{R}{L\left(i\right(t))}dt=ln\left(\frac{i\left(t\right)-i\left(\mathrm{\&infin;}\right)}{i\left(0\right)-i\left(\mathrm{\&infin;}\right)}\right)$

$-\frac{R}{L\left(i\right(t))}=\frac{di/dt}{i\left(t\right)-i\left(\mathrm{\&infin;}\right)}$

Obtain: L (t)=R* (i (∞)-i (t))/(di/dt).

Step 5: reject the skew component in inductance function L (t), obtain effective equivalent inductance L_d。

Although the effect that current curve carries out polynomial curve fitting is better, but can there is bigger deviation in the initial and termination phase of current curve, affect the accuracy of result; Reject the initial and termination phase that deviation is bigger, and retain the intermediate change stable interstage, to obtain inductance function L ' (t) revised:

If dL (t)/dt < M, then L ' (t)=L (t), wherein M is the value being manually set according to inductance function L (t) and derivative thereof.

Again inductance function L ' (t) revised is averaged, namely obtains required effective equivalent inductance L_d:

L_d=mean (L ' (t)).

In the equivalent inductance measuring method of the proportional solenoid according to the present invention, avoid the measurement to temperature, directly utilize relation function L (t) that the current curve of the proportional solenoid of collection obtains the inductance of proportional solenoid, measure the equivalent inductance of proportional solenoid in control process accurately; And the denoising Processing to current curve, it is possible to ensure the effectiveness of the current curve gathered, reject the skew component in inductance function, it is possible to increase the accuracy of the equivalent inductance of proportional solenoid.

In the equivalent inductance measuring method of the proportional solenoid according to the present invention, in one embodiment, the frequency of pwm signal is 500～3000Hz.

In the equivalent inductance measuring method of the proportional solenoid according to the present invention, in one embodiment, the dutycycle of pwm signal is 40%～70%.

In the equivalent inductance measuring method of the proportional solenoid according to the present invention, in one embodiment, the sample frequency of data acquisition module is 300KHz;

In the equivalent inductance measuring method of the proportional solenoid according to the present invention, in one embodiment, the voltage magnitude of pwm signal is 24V.

In the equivalent inductance measuring method of the proportional solenoid according to the present invention, in one embodiment, the number j < 10 of the adjacent current curve of noise processed is eliminated.

In the equivalent inductance measuring method of the proportional solenoid according to the present invention, in one embodiment, adopt five rank or six rank multinomials that current curve is carried out curve fitting.

Secondly hydraulic control method according to a second aspect of the present invention is described.

With reference to Fig. 1, the hydraulic control method according to the present invention, adopt the equivalent inductance measuring method of above-mentioned proportional solenoid, and demarcate the output oil pressure P and input current I and equivalent inductance L of described proportional solenoid_dRelation curve P=f (L_d, I), the output oil pressure P of proportional solenoid is then controlled according to comparative example electromagnetic valve input pwm signal.

According in the hydraulic control method of the present invention, need not utilize temperature sensors for demarcating the oil pressure P impact that electromagnetic valve is exported by oil temperature, and directly by the reacting condition of oil temperature in the change of the equivalent inductance of proportional solenoid, by the equivalent inductance L utilizing the equivalent inductance measuring method of above-mentioned proportional solenoid to measure_dAnd input current I controls the oil pressure P of proportional solenoid output accurately, simplify the structure of oil pressure cntrol and the workload of calibration of sensor.

Claims (8)

1. the equivalent inductance measuring method of a proportional solenoid, it is characterised in that include step:

Step 1:

Comparative example electromagnetic valve input pwm signal, and utilize the data point of voltage signal that data collecting module collected input and the data point of the current signal of correspondence, and then obtain steady-state current voltage waveform; Wherein the frequency of pwm signal is fHz, dutycycle D%, and the voltage magnitude of pwm signal is E; The sample frequency of data acquisition module is FHz, within a cycle of pwm signal, and the number of data points of the number of data points of the voltage signal of collection and corresponding current signal:

The voltage signal in c the cycle of output of pwm signal, the total number of data points collected is c n;

Step 2:

Extracting data current curve from gathering: the voltage of pwm signal input only has two states of 0V and E, if voltage is t from the 0V time point jumping to E₁, voltage is t from the E time point jumping to 0V₂, then at t₁～t₂Time period in current signal be propradation, the current curve obtained is ascending curve; In the data point gathered in step 1, the set of all trip points that voltage jumps to E from 0V is T₁, the set of all trip points that voltage jumps to 0V from E is T₂, T₁And T₁Acquiring method be:

If Volt_(m+1)-Volt_m>E₁, then T₁(k)=t_m;

If Volt_(m+1)-Volt_m<-E₁, then T₂(k)=t_m;

Wherein, t_mRepresent the moment of m point, Volt_mRepresent the magnitude of voltage of m point, and k ∈ (0, m), E₁=0.8E;

If T₂(1)<T₁(1), then T is removed₂(1) corresponding current signal data point; If T₁Number of data points compare T₂Many one of number of data points, then remove T₁The data point of current signal of last correspondence, it is ensured that T₂(1)>T₁(1) and the number of data points of the current signal of correspondence identical; So at arbitrary time period T₁(k)～T₂The k current curve that current curve is kth section that () is corresponding, the current function that this current curve is corresponding is I (k), thus can extract all current curves corresponding to the data point of collection and current function;

Step 3:

Carry out all current curves obtained eliminating noise processed: for pwm signal when the interval of j adjacent current curve is within 2 j, it is considered as electrical characteristic parameter to be not changed in, this j current curve is processed by following formula sum-average arithmetic, to reach to eliminate the effect of noise:

Wherein, I₀K () is the current function after elimination noise, I (k) is the kth section current function intercepted;

Step 4:

Current curve after eliminating noise is carried out polynomial curve fitting, obtains inductance change curve:

Because proportion electro-magnet circuit can regard single order resistance-inductance series circuit as, with common firstorder circuit the difference is that, its inductance is a variable, say, that the time constant of system is not constant, in this case, it is impossible to be fitted with simple exponential type function;

Average current in proportion electro-magnet circuit is that I, I are by the current function I after all elimination noises collected₀K the electric current sum-average arithmetic in () obtains; Equivalent resistance in proportion electro-magnet circuit is R,

When inductance remains unchanged, the inductance in proportion electro-magnet circuit is L, then curent change relation meets following functional relation:

Wherein, i (t) is the relation function of electric current i Yu time t, and i (0) is initial current, and i (∞) is saturation current;

When inductance changes, using inductance function L (i) as electric current, the change procedure of electric current i being divided into l section, the inductance in each section of Δ t regards constant L as_p, then in whole process, curent change meets following functional relation:

When l tends to infinity, the change function of electric current is as follows:

Wherein, i (0) is initial current, and i (∞) is saturation current, and i (∞)=I/ (D%);

To above formula derivation, obtain relation function L (t) of inductance L t in time:

L (t)=R* (i (∞)-i (t))/(di/dt);

Step 5:

Reject the skew component in inductance function L (t), obtain effective equivalent inductance L_d:

Although the effect that current curve carries out polynomial curve fitting is better, but can there is bigger deviation in the initial and termination phase of current curve, affect the accuracy of result; Reject the initial and termination phase that deviation is bigger, and retain the intermediate change stable interstage, to obtain inductance function L ' (t) revised:

If dL (t)/dt < M, then L ' (t)=L (t), wherein M is the value being manually set according to inductance function L (t) and derivative thereof;

Again inductance function L ' (t) revised is averaged, namely obtains required effective equivalent inductance L_d:

L_d=mean (L ' (t)).

2. the equivalent inductance measuring method of proportional solenoid according to claim 1, it is characterised in that the frequency of pwm signal is 500～3000Hz.

3. the equivalent inductance measuring method of proportional solenoid according to claim 1, it is characterised in that the dutycycle of pwm signal is 40%～70%.

4. the equivalent inductance measuring method of proportional solenoid according to claim 1, it is characterised in that the sample frequency of data acquisition module is 300KHz.

5. the equivalent inductance measuring method of proportional solenoid according to claim 1, it is characterised in that the voltage magnitude of pwm signal is 24V.

6. the equivalent inductance measuring method of proportional solenoid according to claim 1, it is characterised in that eliminate the number j < 10 of the adjacent current curve of noise processed.

7. the equivalent inductance measuring method of proportional solenoid according to claim 1, it is characterised in that adopt five rank or six rank multinomials that current curve is carried out curve fitting.

8. a hydraulic control method, it is characterised in that adopt power 1 to the equivalent inductance measuring method of the proportional solenoid weighed described in 7 any one, and demarcate the output oil pressure P and input current I and equivalent inductance L of described proportional solenoid_dRelation curve P=f (L_d, I), the output oil pressure P of proportional solenoid is then controlled according to comparative example electromagnetic valve input pwm signal.