AU2004237787A1

AU2004237787A1 - Control apparatus of electric vehicle, control apparatus of vehicle, and vehicle

Info

Publication number: AU2004237787A1
Application number: AU2004237787A
Authority: AU
Inventors: Seiji Ishida; Wataru Miyake; Motomi Shimada
Original assignee: Hitachi Ltd
Current assignee: Hitachi Ltd
Priority date: 2003-12-16
Filing date: 2004-12-07
Publication date: 2005-06-30
Anticipated expiration: 2024-12-07
Also published as: JP2005204491A; AU2004237787B2

Description

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION NAME OF APPLICANT(S):: Hitachi, Ltd.

ADDRESS FOR SERVICE: DAVIES COLLISON CAVE Patent Attorneys 1 Nicholson Street,Melbourne, 3000, Australia INVENTION TITLE: Control apparatus of electric vehicle, control apparatus of vehicle, and vehicle The following statement is a full description of this invention, including the best method of performing it known to me/us:- 5102

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CLAIM OF PRIORITY 00 The present application claims priority from SJapanese application serial no. 2003-417423, filed on Dec. 16, 2003, and no. 2004-119714, filed on Apr. (1 2004, the content of which are hereby incorporated by reference into these applications.

FIELD OF THE INVENTION The present invention relates to a control apparatus of electric vehicle and vehicle traveling on a truck and to an electric vehicle and vehicle equipped with the control apparatus.

BACKGROUND OF THE INVENTION Railroad vehicle attains its traction force from the adhesion between iron wheel and track but the wheel may sometimes slip when the adhesion coefficient decreases particularly in case of rain. If the wheel slips, the traction force decreases tremendously, it becomes necessary to attain as great traction force as possible while minimizing the wheel slip.

A way for minimizing the slip is disclosed in Japanese Patent Laid-Open No. 2002-345108. According to 2 the Patent Document, wheel is judged slipping when the differentiated rotating speed of motor becomes greater than a judgment criterion, and the wheel slip is minimized by decreasing the torque.

00 SUMMARY OF THE INVENTION Since the apparatus disclosed in the Patent O Document decreases the torque only after the slippage of wheel has increased, there remains a problem that the slippage is apt to increase.

An object of the present invention is to realize a control apparatus of electric vehicle that can minimize the slippage of wheel.

A control apparatus of the present invention controls the motor torque base on the difference between a reference speed calculated from a creep speed reference and vehicle speed and the rotating speed of the motor; and, based on the gradient of the estimated tangential force to the creep speed reference, when the gradient is greater than a preset positive threshold level or the motor torque is greater than a traction force reference given to the control apparatus from an external device, the apparatus controls the creep speed reference so that the motor torque equals to the traction force reference, and when the gradient is smaller than a preset negative threshold level, the apparatus decreases the creep speed reference, and in 3 other cases the apparatus operates the creep speed reference within a preset range including a creep speed reference at which the estimated adhesion force becomes maximum.

OO 5 According to the present invention, a control apparatus of electric vehicle and vehicle that can effectively minimize the wheel slip can be realized.

BRIEF DESCRIPTION OF DRAWINGS Fig. 1 is a block diagram of the embodiment 1.

Fig. 2 is an explanatory diagram of the operation of the embodiment 1.

Fig. 3 is a diagram explaining the first operation the embodiment 1 in case the adhered state worsens.

Fig. 4 is a diagram explaining the second operation the embodiment 1 in case the adhered state worsens.

Fig. 5 is a Figure showing the transition of state in the maximum adhesion force searching section 405.

Fig. 6 is a diagram explaining the third operation the embodiment 1 in case the adhered state worsens Fig. 7 is a block diagram of the embodiment 2.

Fig. 8 is a block diagram of the embodiment 3.

Fig. 9 is a block diagram of the vehicle speed calculator of the embodiment 3.

Fig. 10 is an another block diagram of the vehicle speed calculator of the embodiment 3.

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4 cK DESCRIPTION OF THE PREFERRED EMBODIMENTS

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Detail of the present invention is described hereunder, using figures.

[Embodiment 1] 00 5 An embodiment of the present invention is described hereunder, using Fig. 1 to Fig. 6.

(cN Fig. 1 shows the construction of this embodiment of the invention. In Fig. 1, 1 is a power line, 2 is a track, 3 is a collector, 4 and 7 are wheels, 5 is a receiving reactor, 6 is a motor, 8 and 9 are speed sensors, and 100 is the control apparatus of electric vehicle. Although this embodiment describes about an electric vehicle that is equipped with a single control apparatus and a single motor, the present invention also applies to a case where the electric vehicle is equipped with multiple control apparatuses and multiple motors and also where multiple electric vehicles are coupled with each other.

DC power supplied through the power line 1 and track 2 is received by the collector 3 and wheel 4, and then supplied to the control apparatus 100 via the receiving reactor 5. In the control apparatus, DC voltage is converted to variable-frequency variablevoltage AC voltage and supplied to the motor 6. Then, by driving the wheel 7 by the motor 6, the electric vehicle is driven. The speed sensor 8 outputs the rotating speed wr of the motor 6, and the speed sensor 9 senses the speed of the wheel 4 and outputs the vehicle speed wt, which is the rotating speed of the t motor 6 converted from the vehicle speed, both to the control apparatus 100.

00 5 The control apparatus comprises a filter capacitor 101, inverter 102 as a converter, adhesion force (cN estimating section 103, control selector 104, selector switch 105, adder 106, subtracter 107, coefficient multiplier 108, vector controller 109, pulse width modulation (hereinafter abbreviated as PWM) controller 110, adhered state control section 200, slipped state control section 300, and searching state control section 400.

The filter capacitor 101, constituting a receiving filter together with the receiving reactor eliminates noise component contained in the voltage between the power line 1 and track 2 and also prevents noise current generated in the inverter 102 from running through the power line 1 and track 2. The inverter 102 converts DC voltage to AC voltage by turning on or off the incorporated power semiconductor switching devices such as IGBT according to the output from the PWM controller 110.

The selector switch 105 selects one out of the first creep speed reference wcrl outputted from the adhered state control section 200, second creep speed reference wcr2 outputted from the slipped state control 6 section 300 and third creep speed reference o)cr3 outputted from the searching state control section 400 based on the selection signal Si of the control selector 104 and outputs the fourth creep speed 00 5 reference wcr4. The adder 106 adds the fourth creep speed reference wcr4 and vehicle speed wt outputted (cN from the speed sensor 9, and outputs a reference speed wref. The subtracter 107 subtracts the rotating speed wr outputted from the speed sensor 8 from the reference speed wref, and the coefficient multiplier 108 multiplies the output from the subtracter by a control gain Kp and outputs the second torque reference T2.

The vector controller 109 operates the voltage reference V* so that the second torque reference T2 equals to the torque of the motor 6 on condition that the first torque reference T1 is the upper limit of the motor 6. The PWM controller 110 performs PWM based on the voltage reference The adhesion force estimating section subtracts the toque necessary for accelerating the motor 6 and wheel 4 from the torque outputted from the motor 6 and estimates the adhesion torque between the wheel and rail, converted in terms of the motor shaft. To be concrete, the estimated adhesion torque Tis calculated from the second torque reference T2 and rotating speed (r using the expression T 1 (T2-sJwwr) (1) 1 Tobs 7 In the expression Tob is a time constant for

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determining estimated response, Jw is the moment of inertia of the motor 6 and wheel 4, converted in terms of the motor 6 shaft, and s is a differential operator.

00 5 Description of the control selector 104 will be given later.

c, The adhered state control section 200 comprises a coefficient multiplier 201, subtracter 202, adder 203, and control 204. The coefficient multiplier 201 multiplies the first torque reference T1 instructed to the control apparatus by operator's maneuver or automatic maneuvering system by an inverse of the gain Kp of the coefficient multiplier 108, and the adder 203 adds the output from the coefficient multiplier 201 and output from the control 204 and outputs the first creep speed reference wcrl. The subtracter 202 calculates the difference between the first torque reference T1 and second torque reference T2, and outputs it to the control 204. The control 204 performs a proportional integration control based on the difference between the first torque reference T1 and second torque reference T2.

The slipped state control section 300 comprises a decrease ratio setter 301 and integrator 302. A ratio of decreasing the second creep speed reference cocr2 within a unit time is set in the decrease ratio setter 301, and the ratio is inputted to the integrator 302 so 8 as to decrease the second creep speed reference wcr2.

The searching state control section 400 comprises an increase ratio setter 401, decrease ratio setter 402, selector switch 403, integrator 404, and maximum 00 5 adhesion force searching section 405. A ratio of increasing the third creep speed reference wcr3 within (cN a unit time is set in the increase ratio setter 401, and a ratio of decreasing the third creep speed reference wcr3 within a unit time is set in the decrease ratio setter 402. As the selector switch 403 switches input to the integrator 404 based on the output from the maximum adhesion force searching section 405, the third creep speed reference wcr3 to be outputted from the integrator 404 is increased or decreased. Description of the maximum adhesion force searching section 405 will be given later.

Fig. 2 shows the relationship of the second torque reference T2 and adhesion torque Tadm in terms of the creep speed wcr which is the difference between the vehicle speed wt equivalent to the speed of the vehicle and rotating speed The adhesion torque Tadm is the adhesion force working between the wheel 7 and track 2, that is, driving force of the vehicle, converted in terms of the torque on the shaft of the motor 6. The adhesion torque Tadm is zero when the creep speed wcr is zero. As the creep speed wcr increases, the adhesion torque Tadm increases in the beginning. The 9 adhesion torque Tadm reaches the maximum adhesion torque Tmax at the critical speed wcrmax, but if the creep speed wcr exceeds the critical speed ocrmax, the adhesion torque Tadm decreases. The maximum adhesion 00 5 torque Tmax and critical speed ocrmax depend upon the traveling condition.

Control is performed separately in the adhered state, slipped state and searching state based on the

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gradient of the adhesion torque Tadm to the creep speed wcr. The gradient is positive in the adhered state, negative in the slipped state, and near zero in the searching state.

The control selector 104 senses one of the above three states based on the first torque reference TI, fourth creep speed reference wcr4 and estimated adhesion torque and the selector switch 105 switches the control in accordance with the state.

To begin with, the relationship between the fourth creep speed reference ocr4 and actual creep speed ocr is explained. Since the second torque reference T2 is controlled in proportion to the difference between the reference speed (oref and rotating speed wr, it is proportional to the difference between the fourth creep speed reference ocr4 and creep speed wcr. Accordingly, it has the characteristic shown in a dot-and-dashed line in Fig. 2. The second torque reference T2 has the same as the sum of the adhesion torque Tadm and the 1-10 10 torque necessary to accelerate the wheel 7.

In addition, since the inertia of the motor 6, converted in terms of the shaft, corresponding to the vehicle weight is greater than the inertia of the wheel OO 5 7, the torque needed to accelerate the wheel 7 in 0 response to the vehicle acceleration is nearly negligible. The vehicle, therefore, is operated near C the intersection between the adhesion torque Tadm and second torque reference T2 in Fig. 2. Accordingly, as the fourth creep speed reference wcr4 increase, the actual creep speed wcr also increases.

Because of the above reason, the apparatus judges as adhered state when the gradient of the estimated adhesion torque T- to the fourth creep speed reference wcr4 is greater than a preset positive threshold level, or when the second torque reference T2 is greater than the first torque reference TI, judges as slipped state when the gradient is smaller than a preset negative threshold level, and judges as searching state when the gradient is smaller than the positive threshold level and yet greater than the negative threshold level.

Based on this judgment, the control selector 104 outputs a selection signal SI.

Control under the adhered state is explained hereunder. When adhesion between the wheel 7 and track 2 is favorable and so the maximum adhesion torque Tmax is greater than the first torque reference TI, control 11 under the adhered state is performed. In the adhered state, the selector switch 105 selects the first creep speed reference wcrl and outputs is as the fourth creep speed reference wcr4. In the adhered state control 00 5 section 200 that outputs the first creep speed reference ocrl, control is performed so that the first (cN torque reference T1 equals to the second torque reference T2. If the second torque reference T2 is greater than the first torque reference TI, the output from the subtracter 202 becomes negative, the output from the control 204, first creep speed reference ocrl, fourth creep speed reference wcr4, and reference speed (ref decrease, and so the second torque reference T2 decreases and becomes closer to the first torque reference T1.

Similarly, if the second torque reference T2 is smaller than the first torque reference TI, the second torque reference T2 becomes closer to the first torque reference TI. Accordingly, the control is performed so that the first torque reference T1 second torque reference T2 become equal. Since the second torque reference T2 is feed-forward controlled by the output of the coefficient multiplier 201 in case the first torque reference T1 changes suddenly, high response can be realized. In this instance, the gradient of the estimated adhesion torque T- to the fourth creep speed reference wcr4 is greater than the positive threshold 12 level.

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Control in case the adhesion between the wheel 7 and track 2 worsens, for example, due to rain under this state is described hereunder. As shown in Fig. 3, the characteristic changes from A to B. In the characteristic B, because the maximum adhesion torque C Tmax is smaller than the first torque reference T1, the second torque reference T2 needs to be controlled near the maximum adhesion torque Tmax.

Since the second torque reference Ts becomes greater than the adhesion torque Tadm as the characteristic of the adhesion torque Tadm changes from A to B, the rotating speed (r of the wheel 7 increases and the creep speed wcr increases up to near the intersection between the characteristic B and characteristic of the second torque reference T2. In this instance, because the characteristic of the second torque reference T2 has negative gradient to the creep speed wcr, and so the torque of the motor 6 decreases in accordance with the decrease of the creep speed ocr, the creep speed wcr can be prevented from becoming excessive, that is, remarkable slip can be eliminated.

While the vehicle is operated at the intersection between the characteristic B and characteristic of the second torque reference T2, the second torque reference T2 is smaller than the fires torque reference TI, and so the fourth creep speed reference wcr4 increases. In 13 this instance, because the adhesion torque Tadm and

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estimated adhesion torque T- decrease, and so the gradient of the estimated adhesion torque T- to the fourth creep speed reference wcr4 becomes negative, the 00 5 control selector 104 senses the slipped state and the selector switch 105 selects the second creep speed reference ocr3 and outputs it as the fourth creep speed reference ocr4. When the selector 105 switches the control, the integrator 302 is initialized so that the second creep speed reference ocr2 equals to the existing fourth creep speed reference ocr4.

In the slipped state control section that outputs the second creep speed reference wcr2, because the fourth creep speed reference ocr4 is decreased based on the value of the decrease ratio setter 301, the creep speed ocr becomes closer to the critical speed (ocrmax.

This change is shown in Fig. 4.

As the creep speed ocr comes closer to the critical speed wcrmax, the gradient of the estimated adhesion torque T- to the fourth creep speed reference ocr4 increases and becomes closer to zero. Because of this change, the control selector 104 senses the searching state and the selector switch 105 selects the third creep speed reference ocr3 and outputs it as the fourth creep speed reference ocr4. When the selector 105 switches the control, the integrator 404 is initialized so that the third creep speed reference ocr3 equals to 4 the existing fourth creep speed reference ocr4.

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The searching state control section 400 outputs the t" third creep speed reference ocr3. When creep speed wcr is the same value as critical speed wcrmax, the 00 5 estimated adhesion torque T- becomes the maximum. For this reason, the searching state control section 400 (cN controls the fourth creep speed reference wcr4 near the operating point that the adhesion torque Tadm serves as the maximum.

The operation of the maximum adhesion force searching section 405 is described hereunder, using Fig.

The maximum adhesion force searching section 405 includes two states; increase state and decrease state.

Under the increase state, the selector switch 403 inputs the output from the increase ratio setter 401 into the integrator 404 so as to increase the third creep speed reference wcr3. On the other hand, under the decrease state, it inputs the output from the decrease ratio setter 402 into the integrator 402 so as to decrease the third creep speed reference wcr3.

The initial state in case of transition from the adhered state to the searching state is the increase state, and the initial state in case of transition from the slipped state is the decrease state. Under the increase state, when the fourth creep speed reference ocr4 becomes greater than the sum of the critical creep speed reference wcr4max, which will be described later,

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15 and preset searching width ow, the state transits to the decrease state. Under the decrease state, when the fourth creep speed reference (ocr4 becomes smaller than the difference between the critical creep speed 00 5 reference ocr4max and searching width ww, the state transits to the increase state.

cn Next, how the critical creep speed reference wcr4max is calculated is described hereunder. In case of transition from the adhered state or slipped state to the searching state, or in case transition is caused between the increase state and decrease state, the critical creep speed reference ocr4max is initialized to the fourth creep speed reference ocr4 and also the maximum estimated adhesion torque Tadmmax is initialized to the estimated adhesion torque Tadm.

After this, if the estimated adhesion torque Tadm is greater than the maximum estimated adhesion torque Tadmmax, the critical creep speed ocr4max is updated to the creep speed reference ocr4 and the maximum estimated adhesion torque Tadmmax is updated to the estimated adhesion torque Tadm. Accordingly, the maximum of the estimated adhesion torque Tadm under the present state is stored in the maximum estimated adhesion torque Tadmmax and the fourth creep speed reference ocr4 under the same state is stored in the critical creep speed ocr4max.

Next, concrete operation of the fourth creep speed 16 reference ocr4, estimated adhesion torque critical

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creep speed ocr4max, and maximum estimated adhesion torque Tadmmax is explained hereunder, using Fig. 6. In case of transition from the slipped state to the O 5 searching state, the initial state is the decrease state. Given that the fourth creep speed reference under this state is wcr4(t0) and estimated adhesion 0 torque is the critical creep speed acr4max is

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initialized to o(t0) and the maximum estimated adhesion torque Tadmmax is initialized to Since the present state is the decrease state, the decrease ratio setter 402 is selected and so the fourth creep speed reference ocr4 decreases.

In this instance, because the estimated adhesion torque T^ increases, the critical creep speed wcr4max and maximum estimated adhesion torque Tadmmax are updated successively. As the fourth creep speed reference wcr4 continues decreasing and exceeds ocr4(tl), the estimated adhesion torque T^ starts decreasing, forming a peak at In this instance, the critical creep speed ocr4max and maximum estimated adhesion torque Tadmmax are no longer updated but retained at ocr4(tl) and respectively.

When the fourth creep speed reference (cr4 continues decreasing further and reaches ocr4(t2) which is smaller than ocr4(tl) by the searching width ww, the state transits to the increase state because the 17 condition ocr4 o)cr4max ow is met. After the state

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transits to the decrease state, the fourth creep speed reference ocr4 increases and then, because of the same operation as above, the state transits to the decrease OQ 5 state again at ocr4(t3) where the fourth creep speed reference ocr4 is greater than the ocr4(tl) by the searching width ow. By repeating this operation, the fourth creep speed reference ocr4 is controlled within a range of ±ww from ocr4(tl) at which the estimated adhesion torque T- becomes maximum.

Because of the above operation, high traction force can be realized even if the adhered condition worsens.

In addition, because the fourth creep speed reference is varied, the gradient of the estimated adhesion torque T" corresponding to the fourth creep speed reference ocr4 can be sensed, and accordingly the control selector 104 can perform suitable selection even if the adhered condition varies.

In addition, when the adhered state changes to a favorable state and so the second torque reference T2 becomes greater than the first torque reference TI, the control selector 104 transits to the adhered state and control is performed so that the first creep speed reference ocrl equals to the fourth creep speed reference ocr4 and the first torque reference T1 equals to the second torque reference T2. At the time of transition to the adhered state, the control 204 is T- 18 initialized so that the first creep speed reference wcrl equals to the existing fourth creep speed reference wcr4.

Because of the above operation, when the adhered state changes to a favorable state, control is performed so that the first torque reference T1 equals to the torque generated by the motor 6.

As explained above, the control apparatus of the present invention, equipped with a means for calculating the torque reference based on a traction force reference and a means for controlling the torque of the motor that drives the vehicle wheel based on the torque reference, and further equipped with an adhesion force estimating means that estimates the tangential force of the wheel thread and calculates adhesion force, a rotating speed sensing means that senses the rotating speed of the motor, a reference speed calculating means that calculates the reference speed which maximizes the estimated adhesion force within a range not exceeding the traction force reference, and a torque reference calculating means that calculates the torque reference based on the difference between the reference speed and the rotating speed of the motor, can effectively minimizes the wheel slip.

[Embodiment 2] Another embodiment is described hereunder, using Fig. 7. In Fig. 7, the same component as in Fig. 1 is r 19 given the same symbol, about which no further description is given.

t Fig. 7 shows an embodiment applied to an electric diesel engine locomotive. In Fig. 7, 701 is a diesel 00 5 engine, which is an internal combustion engine, 702 is a generator, and 703 is a rectifier. Power is generated (cN by driving the generator 702 using the diesel engine 701 as a drive source, and the power generated by the generator 702 is rectified to direct current by the rectifier 703 and then supplied to the inverter 102.

The construction of the embodiment shown in Fig. 7 differs from the embodiment 1 only in the means of supplying direct current to the inverter, and so, in case slip is caused on the wheel, it can be effectively minimized by performing the same control as for the above-mentioned embodiment i.

[Embodiment 3] Another embodiment is described hereunder, using Fig. 8. Fig. 8 shows an embodiment where the control apparatus of the present invention is installed on each of multiple unit vehicles coupled to each other. The same component as in Fig. 1 is given the same symbol but with suffix for the first one of the coupled vehicles, suffix for the second one, suffix for the third one, and suffix for the fourth one, about which no further description is given. Although description below covers an embodiment where four more vehicles are coupled, it is needless to say that the invention applies to any embodiment where two or more vehicles are coupled. Each vehicle may be an electric vehicle as explained in the embodiment 1 or electric 00 5 diesel locomotive as explained in the embodiment 2.

In Fig. 8, 801 is a vehicle speed calculating unit, (cN 802 is a terminal unit, 803 is an information transmission line, and each 804a, 804b, 804c and 804d is a terminal unit on each vehicle. In this embodiment, a means for supplying direct current to the control apparatuses 100a, 100b, 100c and 100d is the same as in the embodiment 1 and embodiment 2, and so it is omitted from Fig. 8. The information transmission line can be any cable such as coaxial cable or optical transmission means such as optical fiber cable.

Signal from the speed sensor 8a, 8b, 8c and 8d on each vehicle is inputted to the control apparatus 100a, 100b, 100c and 100d on each vehicle, and the rotating speed era, (rb, wrc and wrd of the wheel of the vehicle driven by each control apparatus is transmitted to the terminal unit 802 with which the vehicle speed calculator 801 is connected from the terminal unit 804a, 804b, 804c and 804d of each vehicle via the information transmission line 803. The terminal unit 802 sends the rotating speed era, (rb, wrc and wrd of the wheel of each vehicle to the vehicle speed calculating unit 801.

The vehicle speed calculating unit 801 calculates the 21 vehicle speed wt through a processing (to be described

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later) and transmits it to the control apparatus 100a, 100b, 100c and 100d on each vehicle via the terminal unit 802, information transmission line 803 and oo 5 terminal unit 804 of each vehicle. The control apparatus 100a, 100b, 100c and 100d on each vehicle controls the motor 6a, 6b, 6c and 6d based on the transmitted vehicle speed wt. In this embodiment, it is sufficient if the vehicle speed calculating unit 801 is installed at least on a vehicle that is attended and maneuvered by operator.

Next, the processing by the vehicle speed calculating unit 801 is described hereunder, using Fig. 9. In Fig. 9, 901 and 903 are minimum value calculating sections, and 902 is a low pass filter. The minimum value calculating section 901 is inputted of the rotating speed era, (rb, wrc and wrd of the wheel of each vehicle from the terminal unit 802, and outputs the first minimum value wminl. The low pass filter 902 shuts out the high-frequency component of the first minimum value wminl and calculates the second minimum value wmin2. The minimum value calculating section 903 outputs either the first minimum value wminl or second minimum value wmin2, whichever smaller, as the vehicle speed wt to the terminal unit 802.

The operation of the vehicle speed calculating unit 801 is described hereunder. When neither of the wheels

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22 is slipping, the rotating speed era, orb, orc and ord

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of the wheel of each vehicle is the same or nearly the same and equals to or nearly equals to the actual vehicle speed. Since the wheel of each vehicle contains a tolerance of the wheel diameter at the time of manufacture, which is for example ±6 mm for a wheel diameter of 800 mm, that is, within the rotating speed of the vehicle wheel has a deviation within ±1% even if the wheel is not slipping. An expression "the rotating speed is nearly the same or nearly equals to" hereinafter in this Specification means the rotating speed is within a deviation of In this instance, the first minimum value ominl is any of the rotating speed eora, orb, corc and ord of the wheel of each vehicle, it equals to or nearly equals to the actual vehicle speed. Since the first minimum value cominl does not involve any such sudden increase as in case of slip, the second minimum value omin2 also equals to or nearly equals to the actual vehicle speed.

Accordingly, the vehicle speed ot, which is either the first minimum value ominl or second minimum value omin2, equals to or nearly equals to the actual vehicle speed.

Next, an occasion where slip is caused on some of the vehicles is described hereunder. In this instance, since the rotating speed of the wheel of the vehicle causing slip becomes greater than the rotating speed of the wheel of the vehicle causing no slip, the minim 23 value calculating section 901 outputs the rotating speed of the wheel of the vehicle causing no slip as the first minimum value (ominl. After this, the vehicle speed ot is controlled equal to or nearly equal to the 00 5 actual vehicle speed through the same operation as explained above under a non-slipped state.

In case slip is caused on all the vehicles, the first minimum value ominl outputted from the minimum

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value calculating section 901 is the rotating speed of the slipped wheel, and so is greater than the actual vehicle speed. In this case, the first minimum value ominl increases suddenly as compared to a normal state causing no wheel slip. On the other hand, the second minimum value wmin2 is prevented from sudden increase because of the function of the low pass filter.

Accordingly, its value is held closer to the actual vehicle speed and so is smaller than the first minimum value ominl, the second minimum value omin2 is outputted as the vehicle speed ot and hence the vehicle speed ot becomes nearly equal to the actual vehicle speed. In addition, as soon as the wheel slip is minimized by the operation of the control apparatus 100a, 100b, 100c and 100d of each vehicle, the first minimum value ominl becomes equal to the actual vehicle speed again. In this instance, since the first minimum value ominl becomes smaller than the second minimum value omin2, the vehicle speed (t equals to the first 24 (,i minimum value wminl and also equals to or nearly equals

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to the actual vehicle speed.

According to this embodiment, as explained above, slip of the wheels can be effectively minimized without 00 5 installing a speed sensor for sensing the vehicle speed separately on each control apparatus 100a, 100b, 100c (cN and 100d.

Although an independent vehicle speed calculator 801 is provided in this embodiment, it is permissible that each control apparatus 100a, 100b, 100c and 100d is equipped with a vehicle speed calculator and the rotating speed data is transmitted to each other via the information transmission line 803 so as to find out the vehicle speed wt. Even in this case, a control apparatus of electric vehicle that can effectively minimize the wheel slip can be realized without installing the speed sensor 9 for sensing the vehicle speed. In addition, since multiple vehicle speed calculators are employed, redundancy against failure can enhance and reliability can improve.

In addition, although the vehicle speed is calculated based on the signal of the wheel speed sensor inputted into the control apparatus in this embodiment, it is also permissible that a speed sensor 1001 mounted on a wheel which does not generate traction force is connected with the information transmission line 803 via a terminal unit 1002 and the 25 vehicle speed is transmitted to each control apparatus 100a, 100b, 100c and 100d of each vehicle. In this case, since the speed sensor 1001 does not generate any traction force, it causes no slip and hence can sense OO 5 the vehicle speed. With this, a control apparatus of electric vehicle that can effectively minimize the wheel slip can be realized. Besides, the speed sensor 1001 can be in common use to an apparatus requiring vehicle speed such as an automatic train stop system.

As explained above, in this embodiment, each of the multiple vehicles is equipped with the control apparatus, the control apparatus of each vehicle is connected with others via the information transmission means, any one of the vehicles is equipped with the vehicle speed calculating means that is inputted of the rotating speed outputted from the controller of each vehicle and calculates the vehicle speed, and the control apparatus of each vehicle increases or decreases the creep speed reference within a range including a level at which the estimated adhesion force becomes maximum, and calculates the reference speed as a sum of the creep speed reference and vehicle speed.

Thus, the wheel slip is effectively minimized.

Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any form of suggestion that that prior art forms part of the common general knowledge in Australia.

Claims

1. A control apparatus of electric vehicle for controlling the motor that drives the wheel of an electric vehicle based on a traction force reference; Swhich is equipped with 00 an adhesive force estimating section that estimates CI the tangential force of the wheel thread and calculates estimated adhesion force, a rotating speed sensing section that senses the rotating speed of the motor, a vehicle speed sensing section that senses the vehicle speed which is the speed of the electric vehicle, a reference speed calculating section that calculates reference speed from a creep speed reference and the vehicle speed, a calculating section that calculates the gradient of the estimated adhesion force to a creep speed reference, a creep speed reference calculating section that calculates the creep speed reference based on the gradient, and a torque reference calculating section that calculates torque reference based on the reference speed and rotating speed; and controls the torque of the motor based on the torque reference.

2. A control apparatus of electric vehicle 27 according to Claim 1, wherein, when the gradient is greater than a preset positive threshold level or the torque reference is greater than the traction force reference, the creep speed reference OO 5 calculating section outputs a creep speed reference so that the traction force reference equals to the traction force generated by the motor, or when the O gradient is smaller than a preset negative threshold level, the section decreases the creep speed reference, or when the gradient is smaller than the positive threshold level and yet greater than thenegative threshold level, or when the torque reference is smaller than the traction force reference, the section controls the creep speed reference within a preset range including a creep speed reference at which the estimated adhesion force becomes maximum.

3. A control apparatus of vehicle equipped with a means for calculating a torque reference based on a traction force reference and a means for controlling the torque of the motor that drives the vehicle wheel based on the torque reference; which is equipped with an adhesion force estimating section that estimates the tangential force of the wheel thread and calculates adhesion force, a rotating speed sensing section that senses the rotating speed of the motor, a reference speed calculating section that 28 calculates a reference speed which maximizes the Sestimated adhesion force within a range not exceeding the traction force reference, and a torque reference calculating section that OO 5 calculates a torque reference based on the deviation 0 between the reference speed and the rotating speed of the motor. C

4. A control apparatus of vehicle according to Claim 3, which is equipped with a vehicle speed sensing section that senses or calculates the vehicle speed of the vehicle, increase or decrease the creep speed reference within a range including a level at which the estimated adhesion force becomes maximum, and calculates a reference speed as a sum of the creep speed reference and the vehicle speed sensed or calculated by the vehicle speed sensing section.

A vehicle equipped with a motor that drives the wheel traveling on a track and a control apparatus that drives the motor at a specified speed; of which control apparatus is equipped with a converter which is inputted of AC voltage and converts to variable-frequency variable-voltage DC voltage to drive the motor, a means for calculating a torque reference based on a traction force reference, and a means for controlling the torque of the motor that drives the vehicle wheel based on the torque -29 reference; and further equipped with an adhesion force estimating section that estimates the tangential force of the wheel thread and calculates adhesion force, OO 5 a rotating speed sensing section that senses the rotating speed of the motor, a reference speed calculating section that C calculates a reference speed which maximizes the estimated adhesion force within a range not exceeding the traction force reference, and a torque reference calculating section that calculates a torque reference based on the deviation between the reference speed and the rotating speed of the motor.

6. A vehicle according to Claim 5; wherein the vehicle is coupled with multiple unit vehicles equipped with the control apparatus; the control apparatuses installed on the multiple unit vehicles are connected with each other via an information transmission means; any one of the unit vehicles is equipped with a vehicle speed calculating unit that is inputted of the rotating speed outputted from a controller installed on each unit vehicle and calculates and outputs the vehicle speed; and the control apparatus installed on each unit vehicle increases or decreases the creep speed reference within a range including a level at which the estimated adhesion force becomes maximum, and calculates a reference speed as a sum of the creep U speed reference and vehicle speed.

7. A vehicle according to Claim 5, wherein the motor is driven by the power which is supplied from a 00 5 power line through a collector and then converted into variable-frequency variable-voltage DC voltage by the (cN converter.

8. A vehicle according to Claim 6, wherein the motor is driven by the power which is supplied from a power line through a collector and then converted into variable-frequency variable-voltage DC voltage by the converter.

9. A vehicle according to Claim 5, wherein the motor is driven by the power which is supplied from a generator, using an internal combustion engine as drive source, and then converted into variable-frequency variable-voltage DC voltage by the converter.

A vehicle according to Claim 6, wherein the motor is driven by the power which is supplied from a generator, using an internal combustion engine as drive source, and then converted into variable-frequency variable-voltage DC voltage by the converter. -31-

11. Control apparatus for an electric vehicle substantially as hereinbefore described with reference to the drawings and/or Examples.

12. A vehicle substantially as hereinbefore described with reference to the drawings and/or Examples.

13. The steps, features, compositions and compounds disclosed herein or referred to or indicated in the specification and/or claims of this application, individually or collectively, and any and all combinations of any two or more of said steps or features. DATED this SEVENTH day of DECEMBER 2004 Hitachi, Ltd. by DAVIES COLLISON CAVE Patent Attorneys for the applicant(s) 5108