CN105799545A - Electric-vehicle braking recharging control system and method - Google Patents

Abstract

An electric-vehicle braking recharging control system comprises an armature current collecting unit, a calculating unit and a recharging mode adjusting unit. The armature current collecting unit is used for collecting a three-phase armature current of a motor of an electric vehicle, and the calculating unit determines a relationship between motor recharging power and an armature current phase angle according to the three-phase armature current, calculates the optimal phase angle under the same armature current and a first limiting current and a second limiting current under the same armature voltage and generates a phase recharging path, wherein the phase recharging path comprises an optimal recharging path, a sub-optimal recharging path and an energy consumption recharging path; the recharging mode adjusting unit is used for adjusting the recharging current of the motor of the electric vehicle to the optimal recharging path or the sub-optimal recharging path or the energy consumption recharging path. In addition, the invention provides an electric-vehicle braking recharging control method. By means of the electric-vehicle braking recharging control system and method, the recharging efficiency can be effectively promoted.

Description

Electric vehicle brake recharges control system and method

Technical field

The present invention relates to electric motor car control field, particularly relate to a kind of electric vehicle brake and recharge control system and method.

Background technology

The drive motor of pure electric vehicle can be taken into account simultaneously drive the function recharged with brake now, brake recharges technology and refers to when driving is decontroled throttle or steps on brake, by car body inertia drive motor, and through the switchover policy of motor driver, make car body kinetic energy transfer battery to and recharge the technology of energy.This technology can be divided many dissimilar by different driver switchover policy at present, and six step conductings substantially can be divided into control and magnetic field steering control two types.Six step conductings control a motor cycle is divided into six steps drive, and its phase current waveform is class square wave, and magnetic field steering control adjusts voltage swing along with different motor angle so that it is phase current waveform type becomes class string ripple, and therefore magnetic field steering control has efficiency height, shakes the characteristics such as little.Permanent magnetic brushless also has two kinds of different types because of its Magnet putting position, and one is surface patch magnetic-type, and this kind of rotor Magnet is affixed on rotor surface, and it two is built-in magnet-type, and this kind of rotor Magnet is built in rotor stalloy.Owing to the rotor of built-in magnet-type has saliency, when making motor inductances projection to synchronous rotary two coordinate axes, two axle inductance will produce difference, also therefore derive the control methods such as weak magnetic control.In addition, the built-in structure of Magnet is also beneficial to the structural strength that motor is lower at a high speed, and therefore built-in magnet-type motor is more beneficial for the application of electric vehicle compared to surface patch magnetic-type motor.

At present, magnetic field steering control recharges the application in control at electric vehicle brake mainly two kinds: the maximum restriction electric current that one is surface patch magnetic-type motor recharges control, after limiting beyond this electric current, the mechanical energy that brake produces will turn is made braking efficiency reduce by electric motor resistance consumption, but this control method is not particularly suited for built-in magnet-type motor；Its two for built-in magnet-type motor unitary current maximum moment magnetic field guiding recharge control, the method can effectively promote the magnetic field guiding of built-in magnet-type motor and recharge control efficiency, but not do not recharge electric current restriction define for maximum, also without considering sub-optimal recharging and the situation such as power consumption recharges.

Summary of the invention

For the problems referred to above, it is necessary to provide a kind of electric vehicle brake controlling better effects if to recharge control system.

Separately, the present invention also provides for a kind of electric vehicle brake and recharges control method.

nullA kind of electric vehicle brake recharges control system，Brake for controlling electric vehicle motor recharges electric current，This electric vehicle brake recharges system and includes armature supply collecting unit、Computing unit and recharge mode regulating unit，This armature supply collecting unit is for gathering the threephase armature electric current of electric vehicle motor，According to above-mentioned threephase armature electric current, this computing unit determines that motor recharges the relation of power and armature supply phase angle，Calculate the optimum phase angle under identical armature supply and first under identical armature voltage limits electric current and the second restriction electric current，And recharge path according to this optimum phase angle generation phase place，This phase place recharges path and includes the best and recharge path、The sub-optimal path that recharges recharges path with power consumption，This recharges mode regulating unit and recharges path with the size of this first restriction electric current and the second restriction electric current the electric current that recharges according to comparative result adjustment electric vehicle motor to the best for comparing armature supply、Sub-optimal recharge path or power consumption recharges path.

A kind of electric vehicle brake recharges control method, is applied to above-mentioned electric vehicle brake and recharges in control system, and this electric vehicle brake recharges control method and includes step:

Acquisition step, to gather the electric current i of described motor threephase armature winding_a、i_bAnd i_c；

Calculation procedure, to determine that motor recharges the relation of power and armature supply phase angle, calculate the optimum phase angle under identical armature supply and first under identical armature voltage limits electric current and the second restriction electric current, and generate phase place according to this optimum phase angle and recharge path, this phase place recharges path and includes the best and recharge path, sub-optimal recharge path and power consumption and recharge path；

Regulating step, to compare armature supply and the size of this first restriction electric current and the second restriction electric current and to regulate the electric current that recharges of electric vehicle motor according to comparative result and recharge path to the best, sub-optimal recharge path or power consumption recharges path.

Described electric vehicle brake recharges control method and recharges current phase angle by adjustment, realize recharging electric current control under optimum phase angle, and by being restricted to described phase place and recharge by recharging electric current path is recharged path by this first restriction electric current and second restriction the best of being formed of electric current division, sub-optimal recharged path and power consumption recharges path, thus being formed, the best recharges, sub-optimal recharging recharges three kinds with power consumption and recharge pattern, can effectively promote electric vehicle brake and recharge efficiency.

Accompanying drawing explanation

Fig. 1 is the theory diagram that the electric vehicle brake of better embodiment of the present invention recharges control system.

Fig. 2 is the coordinate system definition schematic diagram that electric vehicle brake shown in Fig. 1 recharges control system.

Fig. 3 is that electric vehicle brake shown in Fig. 1 recharges the armature supply of the motor of control system and the relation schematic diagram of d-q shaft current.

Fig. 4 be electric vehicle brake shown in Fig. 1 recharge control system recharge current vector figure.

Fig. 5 is the flow chart that the electric vehicle brake of better embodiment of the present invention recharges control method.

Main element symbol description

Phase place recharges path 30

The best recharges path 31

Sub-optimal recharge path 32

Power consumption recharges path 33

First restriction electric current 34

Second restriction electric current 35

Node 36

Recharge current vector 37

First component 3 71

Second component 372

Maximum armature supply restriction circle 38

Electric vehicle brake recharges control system 100

Armature supply collecting unit 110

Computing unit 130

Coordinate transformation unit 131

Recharge power calculation unit 133

Optimum phase angle computing unit 135

The best recharges current calculation unit 137

Sub-optimal recharge current calculation unit 139

Recharge mode regulating unit 150

Following detailed description of the invention will further illustrate the present invention in conjunction with above-mentioned accompanying drawing.

Detailed description of the invention

The present invention provides a kind of electric vehicle brake based on magnetic field steering control to recharge control system 100, recharges current phase angle by adjusting electric vehicle brake, it is achieved the maximum torque control of unitary current, and the electric current promoting electric vehicle motor recharges efficiency.In the present embodiment, described motor is built-in magnet-type permanent magnetic brushless, including stator and rotor.Wherein, stator is threephase armature winding, including the A phase winding of mutual deviation 120 degree, B phase winding and C phase winding on locus.The built-in permanent magnet of this rotor, and can rotate relative to described threephase armature winding.

Seeing also Fig. 1 and Fig. 2, this electric vehicle brake recharges control system 100 and includes armature supply collecting unit 110, computing unit 130 and recharge mode regulating unit 150.This computing unit 130 includes coordinate transformation unit 131, recharges power calculation unit 133, optimum phase angle computing unit 135, the best recharge current calculation unit 137 and sub-optimal recharges current calculation unit 139.This armature supply collecting unit 110 is for gathering the electric current i of described motor threephase armature winding_a、i_bAnd i_c.This coordinate transformation unit 131 is for characterizing in the electric current i of the described threephase armature winding in the three axle two-dimensional coordinate system A-B-C preset_a、i_bAnd i_cThe the first coordinate transform rule transformation preset by one is characterize to fix, in one, the two fixing shaft current i that axis coordinate system alpha-beta is corresponding_α、i_β, then according to a second coordinate transform rule preset by this two fixing shaft current i_α、i_βIt is transformed to and characterizes in two corresponding for rotating shaft coordinate system d-q rotating shaft electric current i_d、i_q.In the present embodiment, described first coordinate transform rule is Clarke conversion, and described second coordinate transform rule is Park conversion.This recharges power calculation unit 133 for converting two rotating shaft electric current i of gained according to this coordinate transformation unit 131_d、i_qWhat calculate motor recharges power P_g, and according to armature supply phase angle θ and two rotating shaft electric current i_d、i_qRelation determine and recharge power P_gRelation with armature supply phase angle θ.This optimum phase angle computing unit 135 is used for calculating identical armature supply i_sUnder optimum phase angle, and according to this optimum phase angle draw phase place recharge path.This best recharges current calculation unit 137 and recharges electric current restriction point for calculating the best under identical armature voltage.This sub-optimal current calculation unit 139 that recharges limits point for the sub-optimal electric current that recharges calculating under identical armature voltage.This recharge mode regulating unit 150 for according to this best recharge electric current restriction point and sub-optimal recharge electric current restriction point regulate this motor recharge electric current.

In coordinate system shown in Fig. 2, γ is the position angle of rotor, and S is the South Pole of rotor Magnet, and N is the rotor Magnet arctic.The electric current i of the motor threephase armature winding that this armature supply collecting unit 110 collects_a、i_bAnd i_cIt is transformed to two corresponding for rotating shaft coordinate system d-q rotating shaft electric current i through this coordinate transformation unit 131_d、i_q.This recharges power calculation unit 133 according to described two rotating shaft electric current i_d、i_qWhat calculate motor recharges power P_gFollowing equation (1):

$P_g=V_{\mathrm{dc}}{I}_{\mathrm{dc}}=\frac{3}{2}r{(i_d+i_q)}^2+\mathrm{T\ω}=\frac{3}{2}r{(i_d+i_q)}^2+\frac{3}{2}\frac{P}{2}\mathrm{\ω}[{\mathrm{\λ}}_m{i}_q+(L_d-L_q)i_d{i}_q]$ Equation (1)

Wherein, V_dcFor armature DC terminal voltage, I_dcFor armature DC terminal electric current, r is the phase resistance of armature, and T is the electromagnetic torque of motor, L_d、L_qThe inductance that respectively two rotating shaft d axles are corresponding with q axle, ω is rotor angular velocity of rotation, λ_mFor the magnetic flux of rotor magnet, P is motor pole number.

Fig. 3 show the armature supply i that electric vehicle brake of the present invention recharges the motor of control method_sWith two rotating shaft electric current i_d、i_qRelation schematic diagram.Armature supply i_sWith two rotating shaft electric current i_d、i_qRelation meet following equation (2):

$\left\{\begin{array}{c}{i}_d=i_s\cos \mathrm{\θ}\\ i_q=i_s\sin \mathrm{\θ}\end{array}\right.$ Equation (2)

Wherein θ is armature supply phase angle.This recharges power calculation unit 133 by armature supply i_sWith two rotating shaft electric current i_d、i_qRelation, i.e. equation (2), substitute into equation (1) and can calculate and obtain recharging power P_gRelation following equation (3) with armature supply phase angle θ:

$P_g=V_{\mathrm{dc}}{I}_{\mathrm{dc}}=\frac{3}{2}{{\mathrm{ri}}_s}^2+\frac{3}{2}\frac{P}{2}\mathrm{\ω}[{\mathrm{\λ}}_m{i}_s\sin \mathrm{\θ}+\frac{1}{2}(L_d-L_q){i_s}^2\sin 2\mathrm{\θ}]$ Equation (3)

Equation (3) is motor and recharges power equation, V_dcI_dcIt is motor and recharges power P_g.Recharge in process in the brake described in the present embodiment, this armature DC terminal electric current I_dcAnd the electromagnetic torque T of motor is negative value.

This optimum phase angle computing unit 135 will recharge power P_gArmature supply phase angle θ carried out partial differential and make secondary partial differential more than zero, obtaining the optimum phase angle under identical armature supply, shown in following equation (4):

$\frac{{\∂P}_g}{\∂\mathrm{\θ}}=0,\frac{{\∂}^2{P}_g}{\∂{\mathrm{\θ}}^2}>0\→\cos \mathrm{\θ}=\frac{-{\mathrm{\λ}}_m-\sqrt{{{\mathrm{\λ}}_m}^2+8{(L_d-L_q)}^2{i_s}^2}}{{4i}_s(L_d-L_q)}$ Equation (4)

This best recharges current calculation unit 137 will recharge power P_gTo armature supply i_sPartial differential to make partial differential result be zero, obtains the best under identical armature voltage and recharges electric current I₁Restriction equation as follows:

$\frac{{\∂P}_g}{{\∂i}_s}=0\→I_1=\frac{-\mathrm{P\ω}{\mathrm{\λ}}_m\sin \mathrm{\θ}}{4r+\mathrm{P\ω}(L_d-L_q)\sin 2\mathrm{\θ}}$ Equation (5)

Due to as armature supply i_sMore than sub-optimal recharge electric current restriction after, the mechanical energy that brake produces will turn and be consumed by resistor power, now will not have any to recharge electric current；Contrary, along with armature supply i_sRecharging electric current restriction beyond sub-optimal, DC terminal, by starting to export the brake machinery energy that electric current provides required, namely enters power consumption brake mode, sub-optimal recharge electric current restriction it follows that described and is armature DC terminal electric current I_dcBy recharging the separation transferring output to, this sub-optimal current calculation unit 139 that recharges is by P_g=0 substitutes into equation (3), can obtain and sub-optimal recharge electric current I₂Restriction equation as follows:

$P_g=0\→I_2=\frac{-2\mathrm{P\ω}{\mathrm{\λ}}_m\sin \mathrm{\θ}}{4r+\mathrm{P\ω}(L_d-L_q)\sin 2\mathrm{\θ}}$ Equation (6)

What the electric vehicle brake of better embodiment of the present invention shown in Fig. 4 recharged control system recharges current vector figure.Wherein, recharging the first component 3 71 and the second component 372 on q direction of principal axis that current vector 37 can be analyzed on d direction of principal axis, wherein the first component 3 71 is d shaft current i_d, second component 372 is q shaft current i_q.By armature supply i_s=0～i_max(i_maxLimit for maximum armature supply) substitute into equation (4) optimum phase angle θ can be calculated₁, then calculated d-q shaft current i by equation (2)_dAnd i_q, draw d-q shaft current i_dAnd i_qNamely the vector path formed obtains phase place and recharges path 30, and described phase place recharges path 30 and intersects at node 36 with maximum armature supply restriction circle 38.Wherein, this maximum armature supply restriction circle 38 is with rotating shaft coordinate system d-q initial point for the center of circle, with i_s=i_maxFor radius.Can being calculated the motor the first restriction electric current 34 under the best recharges pattern by equation (5), this first restriction electric current 34 is positioned at phase place and recharges on path 30.Motor can be calculated at sub-optimal the second restriction electric current 35 recharged under pattern by equation (6), this the second restriction electric current 35 is positioned at phase place and recharges on path 30, and the distance of this second restriction electric current 35 and d-q coordinate origin is more than the distance of this first restriction electric current 34 with d-q coordinate origin.This phase place is recharged path 30 and is divided into the best and recharges path 31, sub-optimal recharge path 32 and power consumption recharges path 33 by this first restriction electric current 34 and the second restriction electric current 35, wherein, the best recharges path 31 between d-q coordinate origin and the first restriction electric current 34, the sub-optimal path 32 that recharges limits between electric current 34 and the second restriction electric current 35 first, and power consumption recharges path 33 and limits between electric current 35 and node 36 second.Therefore, it is limited to the best recharges on path 31 if electric current will be recharged, be the best and recharge pattern；If electric current will be recharged be limited to sub-optimal recharging on path 32, it is and sub-optimal recharges pattern；If electric current will be recharged to be limited to power consumption and recharge on path 33, it is power consumption and recharges pattern.

Referring to Fig. 5, the electric vehicle brake of present pre-ferred embodiments recharges control method and comprises the steps:

Step S1: this armature supply collecting unit 110 gathers the electric current i of described motor threephase armature winding_a、i_bAnd i_c；

Step S2: this coordinate transformation unit 131 will characterize in the electric current i of the described threephase armature winding in the three axle two-dimensional coordinate system A-B-C preset_a、i_bAnd i_cThe the first coordinate transform rule transformation preset by one is characterize to fix, in one, the two fixing shaft current i that axis coordinate system alpha-beta is corresponding_α、i_β, then according to a second coordinate transform rule preset by this two fixing shaft current i_α、i_βIt is transformed to and characterizes in two corresponding for rotating shaft coordinate system d-q rotating shaft electric current i_d、i_q；

Step S3: this recharges power calculation unit 133 for converting two rotating shaft electric current i of gained according to this coordinate transformation unit 131_d、i_qWhat calculate motor recharges power P_g, and according to armature supply phase angle θ and two rotating shaft electric current i_d、i_qRelation determine and recharge power P_gRelation with armature supply phase angle θ；

Step S4: this optimum phase angle computing unit 135 calculates the optimum phase angle θ under identical armature supply₁And the phase place of correspondence recharges path；

Step S5: this best recharges the first restriction electric current 34 that current calculation unit 137 calculates under identical armature voltage；

Step S6: this is sub-optimal recharges the second restriction electric current 35 that current calculation unit 139 calculates under identical armature voltage；

Step S7: this recharges mode regulating unit 150 and recharges electric current for what regulate this motor according to this first restriction electric current 34 and the second restriction electric current 35, wherein, recharge mode regulating unit 150 to recharge electric current and be limited to this best and recharge and path 31 is the best recharges pattern；To recharge electric current be limited to this sub-optimal recharge path 32 is sub-optimal recharge pattern；Electric current will be recharged be limited to this power consumption and recharge and path 33 is power consumption recharges pattern.

Described electric vehicle brake recharges control system and method by adjusting armature supply phase angle θ, it is achieved optimum phase angle θ₁Under unitary current maximum torque control, and calculate optimum phase angle θ₁Under d-q shaft current i_dAnd i_q, draw d-q shaft current i_dAnd i_qThe vector path formed recharges path 30 thus obtaining phase place.Simultaneously, also the changes phase recharging electric current is made a distinction, by arranging different design conditions, obtain being positioned at phase place to recharge the best on path 30 and recharge the first restriction electric current 34 of electric current restriction and sub-optimal the second restriction electric current 35 recharging electric current restriction, it is restricted to described phase place recharges on path 30 by electric current will be recharged, being limited electric current 35 by this first restriction electric current 34 with second to divide the best formed and recharge path 31, sub-optimal recharge path 32 and power consumption recharges path 33, thus being formed, the best recharges, sub-optimal recharging recharges three kinds with power consumption and recharge pattern.Utilize this electric vehicle brake to recharge control system and method can effectively promote electric vehicle brake and recharge efficiency.

The above, be only presently preferred embodiments of the present invention, is not that the present invention does any pro forma restriction.It addition, those skilled in the art also can do other change in spirit of the present invention, certainly, these changes done according to present invention spirit, all should be included within present invention scope required for protection.

Claims (10)

1. null1. an electric vehicle brake recharges control system，Brake for controlling electric vehicle motor recharges electric current，It is characterized in that: this electric vehicle brake recharges system and includes armature supply collecting unit、Computing unit and recharge mode regulating unit，This armature supply collecting unit is for gathering the threephase armature electric current of electric vehicle motor，According to above-mentioned threephase armature electric current, this computing unit determines that motor recharges the relation of power and armature supply phase angle，Calculate the optimum phase angle under identical armature supply and first under identical armature voltage limits electric current and the second restriction electric current，And recharge path according to this optimum phase angle generation phase place，This phase place recharges path and includes the best and recharge path、The sub-optimal path that recharges recharges path with power consumption，This recharges mode regulating unit and recharges path with the size of this first restriction electric current and the second restriction electric current the electric current that recharges according to comparative result adjustment electric vehicle motor to the best for comparing armature supply、Sub-optimal recharge path or power consumption recharges path.
2. 2. electric vehicle brake as claimed in claim 1 recharges control system, it is characterized in that: this computing unit includes coordinate transformation unit, recharge power calculation unit, optimum phase angle computing unit, the best recharges current calculation unit and sub-optimal recharges current calculation unit, it is two rotating shaft electric currents that this coordinate transformation unit is used for threephase armature current transformation, this recharges power calculation unit for determining the relation recharging power with armature supply phase angle, this optimum phase angle computing unit is used for calculating optimum phase angle and phase place recharges path, this the best recharges current calculation unit for calculating this first restriction electric current, this sub-optimal current calculation unit that recharges is for calculating this second restriction electric current.
3. 3. electric vehicle brake as claimed in claim 2 recharges control system, it is characterised in that: described two rotating shaft electric currents characterize in a rotating shaft coordinate system, and this rotating shaft coordinate system includes d axle and q axle, described two rotating shaft electric current respectively i_dAnd i_q, described armature supply is i_s, this armature supply i_sWith this electric current i_d, electric current i_qAnd the relation of armature supply phase angle θ is i_d=i_sCos θ, i_q=i_ssinθ。
4. 4. electric vehicle brake as claimed in claim 3 recharges control system, it is characterised in that: this recharges power and is $P_g=V_{\mathrm{dc}}{I}_{\mathrm{dc}}=\frac{3}{2}{{\mathrm{ri}}_s}^2+\frac{3}{2}\frac{P}{2}\mathrm{\ω}[{\mathrm{\λ}}_m{i}_s\sin \mathrm{\θ}+\frac{1}{2}(L_d-L_q){i_s}^2\sin 2\mathrm{\θ}],$ Wherein, V_dcFor armature DC terminal voltage, I_dcFor armature DC terminal electric current, r is the phase resistance of armature, and T is the electromagnetic torque of motor, L_d、L_qRespectively d axle and q axle inductance, ω is rotor angular velocity of rotation, λ_mFor the magnetic flux of rotor magnet, P is motor pole number.
5. 5. electric vehicle brake as claimed in claim 4 recharges control system, it is characterised in that: the design conditions at this optimum phase angle are $\frac{{\∂P}_g}{\∂\mathrm{\θ}}=0,\frac{{\∂}^2{P}_g}{{\∂\mathrm{\θ}}^2}>0,$ According to this condition by $\cos \mathrm{\θ}\frac{-{\mathrm{\λ}}_m-\sqrt{{{\mathrm{\λ}}_m}^2+8{(L_d-L_q)}^2{i_s}^2}}{{4i}_s(L_d-L_q)}$ Calculating obtains optimum phase angle θ₁。
6. 6. electric vehicle brake as claimed in claim 4 recharges control system, it is characterised in that: the design conditions of this first restriction electric current areAccording to this condition byCalculating obtains the first restriction electric current.
7. 7. electric vehicle brake as claimed in claim 4 recharges control system, it is characterised in that the design conditions of this second restriction electric current are P_g=0, according to this condition byCalculating obtains the second restriction electric current.
8. 8. electric vehicle brake recharges a control method, is applied to electric vehicle brake as claimed in claim 1 and recharges in control system, and this electric vehicle brake recharges control method and includes step:

   Acquisition step, to gather the electric current i of described motor threephase armature winding_a、i_bAnd i_c；

   Calculation procedure, to determine that motor recharges the relation of power and armature supply phase angle, calculate the optimum phase angle under identical armature supply and first under identical armature voltage limits electric current and the second restriction electric current, and generate phase place according to this optimum phase angle and recharge path, this phase place recharges path and includes the best and recharge path, sub-optimal recharge path and power consumption and recharge path；

   Regulating step, to compare armature supply and the size of this first restriction electric current and the second restriction electric current and to regulate the electric current that recharges of electric vehicle motor according to comparative result and recharge path to the best, sub-optimal recharge path or power consumption recharges path.
9. 9. electric vehicle brake as claimed in claim 8 recharges control method, it is characterised in that calculation procedure includes:

   To characterize in the electric current i of the described threephase armature winding in the three axle two-dimensional coordinate system A-B-C preset_a、i_bAnd i_cThe the first coordinate transform rule transformation preset by one is characterize to fix, in one, the two fixing shaft current i that axis coordinate system alpha-beta is corresponding_α、i_β, then according to a second coordinate transform rule preset by this two fixing shaft current i_α、i_βIt is transformed to and characterizes in two corresponding for rotating shaft coordinate system d-q rotating shaft electric current i_d、i_q；

   What calculate motor recharges power P_g, and according to armature supply phase angle θ and two rotating shaft electric current i_d、i_qRelation determine and recharge power P_gRelation with armature supply phase angle θ；

   Calculate the optimum phase angle θ under identical armature supply₁And the phase place of correspondence recharges path；

   Calculating the first restriction electric current under identical armature voltage, wherein this first restriction electric current is positioned at phase place and recharges on path；

   Calculate the second restriction electric current under identical armature voltage, wherein this second restriction electric current is positioned at phase place and recharges on path, and this phase place recharges path and is divided into the best by this first restriction electric current and this second restriction electric current and recharges path, sub-optimal recharge path and power consumption recharges path.
10. 10. electric vehicle brake as claimed in claim 9 recharges control method, it is characterised in that: the design conditions at this optimum phase angle areAccording to this condition by $\cos \mathrm{\θ}\frac{-{\mathrm{\λ}}_m-\sqrt{{{\mathrm{\λ}}_m}^2+8{(L_d-L_q)}^2{i_s}^2}}{{4i}_s(L_d-L_q)}$ Calculating obtains optimum phase angle θ₁。