Control apparatus for electric vehicle

• US 6,255,798 B1
• Filed: 10/23/1996
• Issued: 07/03/2001
• Est. Priority Date: 10/30/1995
• Status: Expired due to Fees

• Current Assignee: Hitachi Car Engineering Company Limited (Hitachi, Ltd.), Hitachi, Ltd.
• Original Assignee: Hitachi Car Engineering Company Limited (Hitachi, Ltd.), Hitachi, Ltd.
• Inventors: Takamoto, Yuusuke, Yamada, Hiroyuki, Masaki, Ryoso, Ohtsu, Eiichi, Obara, Sanshiro
• Primary Examiner(s): MARTIN, DAVID S
• Application Number:
  US08/736,346
• Time in Patent Office: 1,714 Days
• Field of Search: 318/727-818, 318/700-724, 318/432, 318/434
• US Class Current: 318/802
• CPC Class Codes: B60L 15/025 using field orientation; Vector control; Direct Torque Control [DTC]
• CPC Class Codes: B60L 50/51 characterised by AC-motors
• CPC Class Codes: H02P 21/00 Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility

Abstract

A more compact and light-weight drive unit is required for an electric vehicle in order to improve its mileage per charge, acceleration performance and overall efficiency. A control apparatus which generates drive signals to drive power devices in the power converter includes: a current reference generator calculates from a torque reference value a d-axis exciting current reference value on the basis of which the ac motor generates a magnetic flux, and a q-axis torque current reference value, the d-axis and the q-axis being orthogonal to each other; a current control circuit generates ac voltage reference values Vu*, Vv* and Vw* from the d-axis exciting current reference value and the q-axis torque current reference value; and a drive signal generator generates drive signals to drive power devices from the ac voltage reference values. Both the current reference generator and the current control circuit are processed digitally by the same arithmetic unit.

Claims

1. A control apparatus for controlling an electric vehicle having:

ac motor for driving the electric vehicle;

a power converter for supplying power to said ac motor, said power being generated on the basis of an output signal obtained responsive to a drive condition of the vehicle and a speed of the motor;

a control unit for generating a drive signal to actuate power devices in said power converter; and

a torque reference generating means for generating a torque reference value for said motor to generate from the output signal obtained responsive to the drive condition of the vehicle and the speed of the motor, said control apparatus comprising;

current reference generating means for calculating in response to said torque reference value a d-axis exciting current reference value according to which a magnetic flux of said motor is to be generated, and a q-axis torque current reference value, said d-axis and said q-axis being orthogonal to each other; and

current control means for generating ac voltage reference values Vu*, Vv* and Vw* from said d-axis exciting current reference value and said q-axis torque current reference value; and

wherein

said current reference generating means and said current control means are processed digitally by one and the same arithmetic unit.

2. A control apparatus for controlling an electric vehicle according to claim 1, wherein said current reference generating means operates at a frequency dependent on behavior characteristics of an operator, and wherein said current control means, which generates the drive signal for the power converter, operates at a faster frequency than said frequency of said current reference generating means.

3. A control apparatus for controlling an electric vehicle according to claim 2 wherein said current reference generating means is processed at a cycle speed which is slower than a process cycle of said current control means, more specifically at a fraction of a cycle of a target response time constant of the ac motor with respect to said torque reference value.

4. A control apparatus for controlling an electric vehicle according to claim 2 wherein said current control means is processed at a cycle speed in synchronism with a drive signal cycle of the power devices, or at a multiplied cycle thereof or at a fraction of the drive signal cycle.

5. A control apparatus for controlling an electric vehicle having:

ac motor for driving the electric vehicle;

a power converter for supplying power to said ac motor, said power being generated on the basis of an output signal obtained responsive to a drive condition of the vehicle and a speed of the motor;

a control unit for generating a drive signal to actuate power devices in said power converter; and

a torque reference generating means for generating a torque reference value for said motor to generate from the output signal obtained responsive to the drive condition of the vehicle and the speed of the motor, said control apparatus comprising;

current reference generating means for calculating in response to said torque reference value a d-axis exciting current reference value according to which a magnetic flux of said motor is to be generated, and a q-axis torque current reference value, said d-axis and said q-axis being orthogonal to each other;

current control means for generating ac voltage reference values Vu*, Vv* and Vw* from said d-axis exciting current reference value and said q-axis torque current reference value;

wherein said current reference generating means and said current control means are processed digitally by one arithmetic unit;

further wherein said current control means comprises;

three-to-two phase converting means for calculating d-axis and q-axis currents for deriving each feedback value from a motor current relative to the d-axis exciting current references value and the q-axis torque current reference value;

d-axis exciting current control means for calculating a d-axis exciting voltage reference value from a difference between said d-axis exciting current reference value and said d-axis exciting current of feedback;

q-axis torque current control means for calculating each q-axis torque voltage reference value from a difference between said q-axis torque current reference value and said q-axis torque current of feedback;

two-to-three phase converting means for converting said d-axis exciting voltage reference value and said q-axis torque voltage reference value into each ac voltage reference value;

d-axis and q-axis voltage compensating means for compensating said d-axis exciting voltage reference value and said a-axis torque voltage reference value;

ac voltage compensating means for compensating said ac voltage reference value; and

wherein phase angle θ

which is necessary for the two-to-three phase converting means and the three-to-two phase converting means is supplied from phase compensating means in which primary angular frequency ω

1 calculated in ω

1 calculating means is integrated to produce θ

.