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`US005623104A
`
`United States Patent
`
`[191
`
`5,623,104
`Apr. 22, 1997
`[45] Date of Patent:
`Suga
`
`[11] Patent Number:
`
`[54] APPARATUS FOR TESTING POWER
`PERFORMANCE OF ELECTRIC MOTOR
`FOR ELECTRIC VEHICLE
`
`5,262,717
`
`11/1993 Bolegoh .
`
`FOREIGN PATENT DOCUMENTS
`
`[75]
`
`Inventor: Hiroshi Suga, Toyoake, Japan
`
`[73] Assignee: Toyota Jidosha Kabushiki Kaisha,
`Toyota, Japan
`
`[21] Appl. No.: 593,971
`
`[22]
`
`Filed:
`
`Jan. 30, 1996
`
`[30]
`
`Foreign Application Priority Data
`
`Mar. 10, 1995
`
`[JP]
`
`Japan .................................... 7-051385
`
`Int. Cl.6 ........................................................ G01L 3/00
`[51]
`[52] US. Cl.
`..................................... 73l862.18; 73/862.l7;
`73/117
`
`[58] Field of Search ............................ 73/862.18, 862.17,
`73/862.09, 117, 117.1; 364/551.01
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`8/1975 Knoop et a1.
`........................ 73/862.18
`3,898,875
`.
`3/1981
`73/862.18
`4,257,261
`
`5/1983 Ono ...................................... 73/862.18
`4,382,388
`4,422,040 12/1983 Raider et a1.
`.
`4,442,708
`4/1984 Gable et a1.
`......................... 73/862.18
`4,672,288
`6/1987 Abbondanti.
`4,860,231
`8/1989 Ballard et al.
`4,965,513
`10/1990 Haynes et a1.
`
`.
`.
`
`6/1984
`59-104571
`6/1984
`59—111071
`9/1991
`3—212194
`4—348289 12/1992
`6-66653
`3/1994
`
`Japan .
`Japan .
`Japan .
`Japan .
`Japan .
`
`Primary Examiner—Richard Chilcot
`Assistant Examiner—Ronald Biegel
`Attorney, Agent, or Firm—Oblon, Spivak, McClelland,
`Maier & Neustadt, RC.
`
`[57]
`
`ABSTRACT
`
`A test motor 2 is controlled by a controller 7 in accordance
`with travelling pattern (i.e. vehicle speed) data of an electric
`vehicle. A load motor 3 is controlled by a controller 9 in
`accordance with a load pattern. A host controller 10 gener-
`ates the load pattern based on the vehicle speed pattern and
`factors of the electric vehicle, and synchronously outputs the
`vehicle speed pattern and the load pattern to the controller 7
`and 9, respectively. Data detected by a torque sensor 4 or
`other measuring element are input to the host controller 10
`to generate a two-dimensional map showing the relationship
`between the motor efficiency and motor output, or between
`the motor efficiency and revolution speed. Since the load
`pattern is generated and input in advance without using
`feedback control,
`test results can be obtained with high
`accuracy.
`
`6 Claims, 10 Drawing Sheets .
`
`
`
`
`
`
`
`HOST
`
`TEST
`CONTROLLER
`
`“SENSORl"--
`
`
`LOADR
`TORQUE
`MOTOR
`
`
`
`
` MOTOR
`LOAD PATTERN
`
`GENERATION
` MEASURED
`
`
`MEANS
`DATA
`
`
`
` MAP
`
`GENERATION
`
`MEANS
`
`
`
`11
`
`Page 1 of 15
`
`FORD 1404
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`Page 1 of 15
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`FORD 1404
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`

`

`US. Patent
`
`Apr. 22, 1997
`
`Sheet 1 of 10
`
`5,623,104
`
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`Page 2 of 15
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`Page 2 of 15
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`
`
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`

`

`US. Patent
`
`Apr. 22, 1997
`
`Sheet 2 of 10
`
`5,623,104
`
`START
`
`INPUT VEHICLE SPEED DATA BASED
`ON TRAVELLING PATTERN DATA
`
`CALUCULATE ACCELERATION DATA
`FROM MOMENT TO MOMENT
`
`
`
`
`CALUCULATE TORQUE FOR LOAD MOTOR BASED
`ON RUNNING RESISTANCE, TIRE DIAMETER,
`VEHICLE WEIGHT, GEAR RATIO, ETC.
`
`
`
`
`GENERATE REVOLUTION SPEED
`PATTERN FOR TEST MOTOR
`
`‘
`
`
`
`
`GENERATE TORQUE PATTERN FOR LOAD MOTOR
`SYNCHRONIZED WITH THE REVOLUTION
`SPEED PATTERN FOR TEST MOTOR
`
`
`
`
`3101
`
`S102
`
`S103
`
`S104
`.
`
`S1 05
`
`SYNCHRONOUSLY CONTROL BOTH
`TEST MOTOR AND LOAD MOTOR
`
`.
`
`S106
`
`INPUT AND ANALIZE MEASURED DATA
`
`$107
`
`.31]?-
`
`Fig. 2
`
`Page 3 of 15
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`Page 3 of 15
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`

`

`US. Patent
`
`Apr. 22, 1997
`
`Sheet 3 of 10
`
`5,623,104
`
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`
`Page 4 of 15
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`FORD 1404
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`Page 4 of 15
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`FORD 1404
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`

`

`US. Patent
`
`Apr. 22, 1997
`
`Sheet 4 of 10
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`Page 5 of 15
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`

`

`US. Patent
`
`Apr. 22, 1997
`
`Sheet 5 of 10
`
`5,623,104
`
`TIME
`
`
`
`SPEED
`
`
`
`(B)MOTOR2
`
`D:
`
`O '
`
`— O E ‘
`
`5,
`
`Page 6 of 15
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`FORD 1404
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`Page 6 of 15
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`FORD 1404
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`

`

`US. Patent
`
`Apr. 22, 1997
`
`Sheet 6 of 10
`
`5,623,104
`
`
`
`
`
`
`
`POWERING
`
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`
`0MOTOROUTPUT
`
`REGENERATION
`
`9L
`
`
`
`D
`
`MOTOR EFFICIENCY :
`
`D O O (
`
`5
`
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`Page 7 of 15
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`

`

`US. Patent
`
`Apr. 22, 1997
`
`Sheet 7 of 10
`
`5,623,104
`
`
`
`1%UPHILLGRADIENTINLA#4
`
`
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`
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`
`Page 8 of 15
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`FORD 1404
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`Page 8 of 15
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`FORD 1404
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`

`

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`Page 9 of 15
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`

`

`US. Patent
`
`Apr. 22, 1997
`
`Sheet 9 6f 10
`
`5,623,104
`
`TORQUE [Nm]
`
`MOTOR EFFICIENCY [%]
`I:
`
`'
`
`V
`
`III:IIIIE:
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`
`Fig.9
`
`Page 10 of 15
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`

`

`US. Patent
`
`Apr. 22, 1997
`
`Sheet 10 of 10
`
`5,623,104
`
`
`
`
`
`REVOLUTIONSPEED[rpm]
`
`Fig.10
`
`[um] anoum uoxow
`
`Page 11 of 15
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`

`1
`APPARATUS FOR TESTING POWER
`PERFORMANCE OF ELECTRIC MOTOR
`FOR ELECTRIC VEHICLE
`
`BACKGROUND OF THE INVENTION
`
`This invention relates to an apparatus for testing electric
`motor performance, and more particularly to an apparatus
`for testing the power performance of an electric motor for an
`electric vehicle.
`
`Generally, when evaluating the performance of an electric
`motor (hereinafter referred to as a test motor) on a test
`bench, performance testing is carried out under two different
`evaluation circumstances,
`i.e. evaluation under constant
`conditions (with constant revolution and constant torque)
`and evaluation under acceleration/deceleration operations.
`Test driving with acceleration/deceleration operations fur-
`ther includes a simple driving pattern and a mode simulating
`for actual travel of a vehicle. Under the simulation mode, the
`motor revolution is controlled so that the vehicle speed
`indicates a predetermined running pattern (for example,
`LA#4 mode based on actual driving in Los Angeles, Calif),
`while generating a resistance corresponding to’an actual
`running resistance using a load motor.
`Controlling of the running resistance is carried out by
`computing a load on the vehicle based on the revolution of
`the test motor (i.e. vehicle speed) and outputting the com-
`puted load value to the load motor. The load motor has a
`computing unit for calculating the running resistance in its
`control system.
`Conventionally, several techniques are known for calcu-
`lating running resistance. One technique is to calculate a
`load from a load map which is preset in response to a vehicle
`speeden this case, the test bench should be provided with
`an element having an inertia equivalent to the vehicle inertia
`(e.g. a flywheel) and resistance equivalent to the vehicle
`speed is applied to the test apparatus as a load.
`Alternatively, load may be calculated based on a feedback
`speed/acceleration of the load motor, vehicle weight, air
`resistance factor, etc. When carrying out a performance test
`on a test bench using this technique, feedback speed and
`acceleration of the load motor must be accurately measured
`to provide an appropriate load in accordance with the
`measurement result.
`
`Japan Laid Open (Kokai) H3-212194 discloses a structure
`of outputting a speed command (torque command) to the test
`motor in accordance with a travelling schedule of the
`vehicle, while outputting to the load motor a resistance
`(torque) corresponding to travelling conditions at the feed—
`back speed and acceleration. Each of the operations are
`controlled by a microcomputer.
`However, in the former technique using a flywheel, the
`mechanical strength of the test bench must be reinforced in
`order to mount the flywheel, which causes the test apparatus
`to become larger as well as more expensive.
`On the other hand, in calculating a load based on the
`feedback speed and acceleration of the load motor (in the
`latter technique), it is difficult to detect an acceleration with
`high accuracy due to the influence of discrete errors in
`digital systems and the influence of noise in analogue
`systems. The detection error in acceleration may provide an
`unrealistic load value and prevent
`the providing of an
`appropriate running resistance.
`Furthermore, presence of time delay is inevitable during
`the measurement of the fedback speed and acceleration, and
`it adversely affects reproduction of the measured value. In
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`5,623,104
`
`2
`
`order to reduce the time delay, the accuracy of the micro-
`computer must be improved, which results in increased cost.
`
`SUMMARY OF THE INVENTION
`
`This invention was conceived in view of the above-
`
`mentioned problems and it is an object of the invention to
`provide an apparatus for testing the power performance of
`an electric motor which realizes highly accurate and effec-
`tive testing of a test motor.
`In order to achieve the object, a test apparatus of the
`invention carries out a power performance test of an electric
`motor for an electric vehicle by driving an electric motor to
`be mounted on an electric vehicle and a load motor con—
`nected to the electric motor. The test apparatus comprises
`electric motor control means for controlling the electric
`motor in accordance with a predetermined travelling pattern
`of the electric vehicle, load motor control means for con-
`trolling the load motor in accordance with a predetermined
`load pattern, and main control means for synchronously
`controlling an operation timing of the electric motor control
`means and the load motor control means.
`
`In this structure, the main controller synchronously con-
`trols the electric motor control means and load motor control
`means in accordance with a predetermined speed pattern and
`a predetermined load pattern, respectively, rather than using
`a conventional feedback control to determine a torque for
`the load motor. Accordingly, control delay arising from a
`feedback delay is obviated, and also, errors in torque com—
`mand values caused by detection error in acceleration can be
`avoided. Consequently, accurate test results of the power
`performance of the motor are obtained.
`The apparatus for testing the performance of the electric
`motor further comprises means for generating the load
`pattern based on the travelling pattern and various factors of
`the electric vehicle. By simply setting the travelling pattern
`and the values of the electric vehicle factors, the load pattern
`is automatically generated and performance tests under
`various travelling conditions are easily realized without
`complicated process for generating the load pattern.
`The apparatus for testing the performance of the electric
`motor further comprises detection means for detecting at
`least torque, revolution speed, driving electric current and
`driving voltage, and map generation means for generating a
`two-dimensional map showing the relationship between the
`output torque of the electric motor and the motor efiiciency
`based on the detected values.
`
`The map generation means may generate a two-dimen—
`sional map showing the relationship .between the revolution
`speed of the electric motor and the motor efficiency based on
`the detected values.
`
`By generating a two—dimensional map containing a physi-
`cal value of the efficiency,
`the tendency of the motor
`performance is easily understood.
`Other objects and advantages will be apparent from the
`detailed description of the embodiment with reference to the
`drawings.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is a schematic diagram of a test apparatus in
`accordance with the invention.
`
`FIG. 2 is a flowchart showing operations of the test
`apparatus of FIG. 1.
`FIG. 3 illustrates a travelling pattern of LA#4 used in the
`embodiment.
`
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`FIG. 4 illustrates a torque pattern used in the embodiment
`which corresponds to the travelling pattern of FIG. 3.
`FIG. 5 illustrates a revolution speed and a torque which
`are output from the host computer 10 to the test motor and
`load motor, respectively.
`FIG. 6 shows evaluation results for a 0% uphill gradient
`obtained by the test apparatus in accordance with the
`embodiment, mapped on a two-dimensional map of motor
`efliciency vs. motor output.
`FIG. 7 shows evaluation results for a 1% uphill gradient
`obtained by the test apparatus in accordance with the
`embodiment.
`
`FIG. 8 shows another display example of evaluation
`results mapped on a graph with torque vs. revolution speed.
`FIG. 9 shows still another display example of evaluation
`results showing torque, revolution speed and motor effi-
`ciency.
`FIG. 10 shows evaluation results obtained by a conven-
`tional test apparatus.
`
`10
`
`15
`
`20
`
`and outputs a two-dimensional map of the relationship
`between the revolution speed and the efficiency (or between
`the motor output and the efiicieney) .
`The operation of the test apparatus will now be described
`with reference to the flowchart of FIG. 2.
`
`Vehicle speed pattern data is input to the host controller 10
`using traveling mode data (8101). In the embodiment, LA#4
`mode shown in FIG. 3 is used. The host controller 10
`calculates an acceleration data from moment to moment
`
`based on the vehicle speed pattern data (8102). More
`particularly, the acceleration data is obtained by time- dif-
`ferentiating the travelling pattern in FIG. 3. After calculating
`the acceleration pattern in 8102,
`the host controller 10
`calculates a torque, which is to be Supplied to the load motor
`3, based on the running resistance, tire diameter, vehicle
`weight, and gear ratio of the vehicle on which the test motor
`is mounted (8103). The torque is calculated using the
`following equation:
`
`Output torque =running resistance+acceleration/deceleration resis-
`tance
`
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENT
`
`FIG. 1 shows a system structure in accordance with one
`embodiment of the invention. A test motor 2 and a load
`motor 3, which are mechanically connected to each other
`through a coupling shaft, are set on a test bench 1. A torque
`sensor 4 is provided on the coupling shaft to detect an output
`torque of the test motor 2. An inverter 6 is connected to the
`test motor 2 and an invertor 8 is connected to the load motor
`3. Switching operation of the invertor 6 is controlled by a
`controller 7 which serves as an electric motor controlling
`means, while switching operation of the invertor 8 is con-
`trolled by a controller 9 which serves as a load motor control
`means. The inverters 6 and 8 are connected to a DC power
`source 11 and convert
`the direct current
`to alternating
`current to drive the respective motors 2 and 3. The control-
`lers 7 and 8 are connected via a dedicated data bus 12 to a
`host controller 10 which serves as a high order main
`controlling means to generally control the two motors. The
`host controller 10 comprises a motor interface unit, a mea-
`surement control unit, and a display analysis unit which
`functions as a map generation unit 10b as will be described
`below. The host controller 10 outputs a high-speed sync
`signal at an electrically constant time period from the motor
`interface unit and supplies it via the dedicated data bus 12 to
`the controllers 7 and 9 for a synchronizing operation com-
`mand. Since the controllers 7 and 9 generate their own
`control signal based on the sync signal, the synchronism of
`the motors 2 and 3 are assured. The high-speed sync signal
`provides an operation command at a shorter time period than
`the mechanical time constant of both the motors 2 and 3,
`which allows various driving patterns ranging from a simple
`pattern to a complicated operation pattern.
`The host controller 10 further includes a load pattern
`generation unit 10a for calculating a load pattern from the
`various vehicle factors in the travelling mode, details of
`which will be described below.
`
`A measure unit 13 is provided to detect various param-
`eters such as a revolution speed, electric current and voltage
`of the test motor 2. The detection signals from the measure
`unit 13 as well as a detection signal from a torque sensor 4
`are supplied to the host controller 10. The display analysis
`unit of the host controller 10 calculates an efliciency of the
`test motor 2 based on the detection signals, and generates
`
`The running resistance is obtained by either of the fol—
`lowing methods.
`
`25
`
`(A) Mapping Method
`
`Running resistance values corresponding to each of a
`number of vehicle speeds are input
`in advance, and a
`running resistance at a given vehicle speed is obtained by
`linear interpolation.
`'
`
`(B) Calculation Method I
`
`Running resistance values corresponding to each of a
`number of vehicle speeds are input in advance, and the
`constants in the following equation are determined to obtain
`an approximation curve.
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`Running resistance=A+BV+CV2
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`where A, B and C represent constants and V represents
`vehicle speed.
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`(C) Calculation Method 11
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`Traveling resistance is calculated in accordance with the
`following equation.
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`Traveling resistance=1/z * CD * S * p(V/3.6)2+ng
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`where V is vehicle speed, CD is air resistance coefficient, S
`is projected front area of vehicle, p is air density, p is rolling
`resistance coefficient, W is vehicle weight, and g is the
`acceleration of gravity.
`The present invention is characterized in that the host
`controller 10 generates a torque in advance which is to be
`provided. to the load motor 3, and either method among
`(A)—(C) can be used to obtain the traveling resistance.
`Acceleration/deceleration resistance may be calculated
`from the following equation.
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`Acceleration/deceleration resistance=ng * dV/dt
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`After calculating the torque to be sent to the load motor
`3, the host controller 10 generates a revolution speed pattern
`which is to be supplied to the test motor 2 (8104). The
`revolution speed pattern is generated based on the vehicle
`speed pattern data input in the step 8101. As has been
`described,
`in the embodiment,
`the vehicle speed pattern
`shown in FIG. 3 is generated based on LA#4 mode. Then, a
`torque pattern which synchronizes with the vehicle speed
`pattern of the test motor 2, is generated for the load motor
`3 (8105). The torque may be calculated by either of the
`above-mentioned methods (A) to (C), and an example of the
`generated torque pattern is illustrated in the lower half of
`FIG. 4. In FIG. 4, the upper half is a vehicle speed pattern
`for the test motor 2 represented by a revolution speed (the
`pattern itself is therefore the same as that of FIG. 3), while
`the lower half is a torque pattern for the load motor 3 which
`is synchronized with the vehicle speed pattern. The synchro-
`nized vehicle speed pattern and torque pattern are output via
`the data bus 12 to the test motor 2 and load motor 3,
`respectively (8106). FIG. 5 shows an example of the vehicle
`speed pattern and torque pattern output from the host
`controller 10. FIG. 5(A) is a vehicle speed pattern output to
`the test motor 2 (actually to the controller 7), and FIG. 5(B)
`is a torque pattern output to the load motor 3 (actually to the
`controller 9). Both patterns are synchronized with each
`other, and therefore, control delay in feedback is dissolved.
`In step 8107, various data are detected by the torque
`sensor 4 and other measurement unit 13 while controlling
`the test motor 2 and load motor 3 in the synchronized '
`manner. The detected data are input to the display analysis
`30
`unit of the host controller 10 for data analysis (8107).
`Analysis includes a calculation of the efficiency of the test
`motor 2 and a mapping of the relationship between the
`efiiCiency and motor output or between the efliciency and the
`motor revolution speed or motor electric current (or voltage)
`on a two-dimensional map. The efficiency is obtained using
`the following equation.
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`35
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`Eflicieucy=2(T*M/Z(I*V)
`
`where T represents torque, N is revolution speed, I is
`electrical current, and V is voltage.
`FIG. 6 shows an example of the relationship between the
`calculated efiiciency and motor output mapped on a two-
`dirnensional map. The horizontal axis represents a motor
`output (kW) and the vertical axis represents an efficiency
`(%). Although it is not shown in the figure, each data point
`on the map bears a number indicating the order in which the
`data is obtained, and is expressed as time-sequence data on
`two—dirnensional map. Since the vehicle speed for the test
`motor 2 and torque for the load motor 3 are calculated in
`advance and are output in a synchronized manner, control
`delay is substantially eliminated. Furthermore,
`reduced
`accuracy in the acceleration detection is avoided and highly
`accurate data can be obtained in a short time period as well
`as easy detection of the center of gravity of the motor output.
`Generally, motor is designed so that a periphery of the center
`of gravity is optimally designed. By obtaining the evaluation
`results as shown in FIG. 6, the scope of the optimal design
`is easily set.
`FIG. 10 shows an example of test results obtained by a
`conventional test apparatus, for comparison, where the hori-
`zontal axis represents motor revolution speed (rpm) and the
`vertical axis represents motor torque (Nm). Dots in the chart
`are measuring points, and motor efficiency is calculated at
`each of the measuring points. In such a conventional test
`apparatus, it is difiicult to know a tendency of the motor
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`efficiency or causality of energy loss. Comparing this plot
`with the evaluation results shown in FIG. 6, the advanta-
`geous effect of the test apparatus of the invention will be
`apparent.
`Although the evaluation result of FIG. 6 is on the assump—
`tion of a 0% uphill gradient in LA#4, the test apparatus of
`the present invention can easily be applied to any traveling
`pattern because vehicle speed pattern and torque pattern are
`calculated and provided to the host controller in advance.
`For example, FIG. 7 shows an evaluation result of a 1%
`uphill gradient in LA#4. This test result can be obtained by
`simply correcting the torque pattern given to the load motor
`for a 0% uphill gradient.
`FIG. 8 illustrates more evaluation results showing a motor
`efficiency distribution for each given time, with revolution
`speed as a horizontal axis and output torque as a vertical
`axis. Although a three-dimensional graphic is generally used
`for expressing the relationship among the revolution speed,
`torque and efficiency, FIG. 8 two-dimensionally expresses
`the relationship by plotting the efficiency with different
`colors for each levels. The region “a” is plotted in red, the
`region “b” is plotted in orange, the region “c” is plotted in
`yellow, and the region “d” is plotted in yellow-green. The
`efficiency is decreased in the order of red, orange, yellow
`and yellow-green. Thus, the efficiency distribution of the
`motor is graphically expressed as isobaric lines and is easily
`and visually analyzed. If abnormal color distribution appears
`on the graph, it is determined that there is something wrong
`with the motor and the motor can be quickly checked and
`redesigned. Similar to FIG. 6, each data point may bear a
`number showing the order of the measurement.
`FIG. 9 shows another graph showing the evaluation
`results. The horizontal axis represents time and the vertical
`axis represents revolution speed, torque, and efficiency. In
`this graph, the relationships between revolution speed and
`time, between output torque and time, and between efii—
`ciency and time are incorporated in the same two—dimen-
`sional area, and the revolution speed, output torque and
`motor efliciency are associated with each other on a time
`basis. Therefore, it is easily and quickly determined which
`driving pattern leads to the reduced efliciency.
`Three preferred examples of displaying the evaluation
`results have been shown above. However, since one of the
`features of the invention 'is to create the two-dimensional
`map containing a physical amount of motor efliciency, other
`display methods are also included in the scope of the present
`invention as long as they show the relationship between
`motor efficiency and other parameters such as torque or
`revolution speed.
`What is claimed is:
`1. An apparatus for testing the power performance of an
`electric motor for an electric vehicle by driving the electric
`motor to be mounted on the electric vehicle and a load motor
`connected to the electric motor, comprising:
`electric motor control means for controlling the electric
`motor in accordance with a predetermined travelling
`pattern of the electric vehicle said traveling pattern
`having at least one acceleration or deceleration portion;
`load motor control means for controlling the load motor
`in accordance with a predetermined load pattern; and
`main control means for synchronously controlling the
`operation timing of the electric motor control means
`and the load motor control means.
`
`2. The apparatus according to claim 1, further comprising
`means for generating the load pattern based on the travelling
`pattern and factors of the electric vehicle.
`3. The‘ apparatus according to claim 2, wherein said load
`pattern is an addition of a running resistance and an accel-
`eration/deceleration resistance of the electric vehicle.
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`4. The apparatus according to claim 3, wherein the
`acceleration/deceleration resistance is calculated based on
`the acceleration obtained by time-differentiating a vehicle
`speed of the travelling pattern.
`5. The apparatus according to claim 1, further comprising:
`
`6. The apparatus according to claim 1, further comprising:
`
`detection means for detecting at least a torque, revolution
`speed, driving electric current, and driving voltage of
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`5
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`the electric motor; and
`
`detection means for detecting at least a torque, revolution
`speed, driving electric current, and driving voltage of
`the electric motor; and
`
`map generation means for generating a two-dimensional
`map showing the relationship between the output and 10
`efficiency of the electric motor based on the detected
`values.
`
`map generation means for generating a two-dimensional
`map showing the relationship between the revolution
`speed and efiiciency of the electric motor based on the
`
`detected values.
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`*
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