Apparatus for driving electric car by inverter-controlled motor through gear mechanism

• US 6,431,297 B1
• Filed: 02/14/2000
• Issued: 08/13/2002
• Est. Priority Date: 02/18/1999
• Status: Expired due to Term

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Nakazawa, Yosuke
• Primary Examiner(s): Johnson, Brian L.
• Assistant Examiner(s): SHRIVER II, JAMES A
• Application Number:
  US09/504,104
• Time in Patent Office: 911 Days
• Field of Search: 180/65.1, 180/65.3, 180/65.4, 180/65.5, 180/65.6, 180/65.8
• US Class Current: 180/65.6
• CPC Class Codes: B60L 15/2054 by controlling transmissions or clutches
• CPC Class Codes: B60L 2200/26 Rail vehicles
• CPC Class Codes: B60L 2210/20 AC to AC converters
• CPC Class Codes: B60L 2220/46 Wheel motors, i.e. motor connected to only one wheel
• CPC Class Codes: B60L 2220/58 with more than three phases
• CPC Class Codes: B60L 50/51 characterised by AC-motors
• CPC Class Codes: B60L 9/22 polyphase motors
• CPC Class Codes: B60L 9/28 polyphase motors
• 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

An apparatus for driving and controlling a car has a large gear directly connected to a wheel shaft of the car, small gears meshing with the large gear, AC motors connected to the small gears, respectively, and inverters whose AC output sides are connected to the AC motors, respectively, and whose DC input sides are connected in series in multiple stages to a high-voltage DC power source. Torque for driving the large gear connected to the wheel shaft is divided and borne by the small gears, so that each small gear receives small torque. This enables each tooth of each gear to have small mechanical strength. As a result, the cross-sectional area of each tooth of each small gear can be reduced to increase the number of teeth of the large gear that meshes with the small gears, to increase a gear ratio defined by the large and small gears. The DC input terminals of the inverters are connected in series to the high-voltage DC power source, and a DC input voltage for each inverter is reduced to a standard inverter level. Consequently, the inverters of the apparatus may be mass-produced standard inverters.

Claims

1. An apparatus for driving and controlling a car, comprising:

a large gear directly connected to a wheel shaft;

small gears meshing with the large gear;

AC motors connected to the small gears, respectively;

standard inverters connected to the AC motors, respectively, for supplying power thereto, DC inputs sides of the inverters being connected in series in multiple stages to a high-voltage DC power source so as to divide a voltage of the DC power source into standard voltage for each of the inverters; and

an inverter controller provided for each of the inverters, for receiving a DC source voltage value detected on a power-source transmission line and an input voltage value detected at the inverter, finding a difference between the input voltage value and a quotient obtained by dividing the DC source voltage value by the number of the inverters, and correcting an output torque command for the inverter according to the difference.

4. The apparatus of claim 1, further comprising:

a short-circuit switch provided for each of the inverters between positive and negative DC input terminals of the inverter, for short-circuiting the inverter if the inverter fails, so that the remaining inverters may continue to operate.

5. The apparatus of claim 4, further comprising:

a power source disconnection switch for disconnecting the DC power source from the DC input sides of the inverters on condition that at least one of the inverters fails so that the remaining inverters continue to operate and that a DC source voltage from the DC power source exceeds the sum of allowable input DC voltages of the operating inverters.

6. The apparatus of claim 1, further comprising:

an inverter controller for preparing an inverter output voltage command according to a composite value of output currents of the inverters so that the inverters may provide pulse patterns according to the same voltage command.

7. The apparatus of claim 1, wherein frames of the AC motors are electrically short-circuited to a power source ground, and further comprising:

an inverter controller for providing a phase difference for a triangular wave that is used to form a PWM pulse pattern of each inverter.

2. An apparatus for driving and controlling a car, comprising:

a large gear directly connected to a wheel shaft;

small gears meshing with the large gear;

AC motors connected to the small gears, respectively;

inverters connected to the AC motors, respectively, for supplying power thereto, DC input sides of the inverters being connected in series in multiple stages to a DC power source of high-voltage so as to divide a voltage of the DC power source into a standard voltage for each of the inverters; and

an inverter controller provided for each of the inverters, for calculating an output effective power value according to an input DC voltage value and an input DC current value both detected at the inverter, calculating an effective power command value according to a motor angular frequency and a torque command value, calculating a difference between the output effective power value and the effective power command value, and correcting the torque command value according to the difference.

3. An apparatus for driving and controlling a car, comprising:

a single large gear directly connected to a wheel shaft;

a single small gear meshing with the large gear;

a single 3-by-n phase AC motor wherein n is an integer equal to or larger than 2, connected to the small gear;

n inverters for supplying power to the AC motor, DC input sides of the inverters being connected in series in n stages to a high-voltager DC power source; and

an inverter controller provided for each of the inverters, for receiving a DC source voltage value detected at the DC power-source and an input voltage value detected at the inverter, finding a difference between the input voltage value and a quotient obtained by dividing the DC source voltage value by n, and correcting an output torque command for the inverter according to the difference.

8. The apparatus of claim 3 further comprising:

a short-circuit switch provided for each of the inverters between positive and negative DC input terminals of the inverter, for short-circuiting the inverter if the inverter fails, so that the remaining inverters may continue to operate.

9. The apparatus of claim 3, wherein the AC motor is a permanent-magnet synchronous motor, further comprising:

an inverter controller for controlling, if at least one of the inverters fails, the remaining inverters to pass a current in a direction to a motor induced voltage so as to prevent the AC motor from producing a short-circuit torque current.