Driving system for electric vehicle

• US 6,236,172 B1
• Filed: 06/29/1999
• Issued: 05/22/2001
• Est. Priority Date: 05/29/1996
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Obara, Sanshiro, Shibukawa, Suetaro, Katada, Hiroshi, Naito, Shotaro, Matsudaira, Nobunori
• Primary Examiner(s): Ro, Bentsu
• Application Number:
  US09/599,099
• Time in Patent Office: 693 Days
• Field of Search: 318/138, 318/139, 318/254, 318/439, 318/459, 318/500, 318/700, 318/720-724, 388/928.1
• US Class Current: 318/139
• CPC Class Codes: B60L 15/08 using pulses
• CPC Class Codes: B60L 2220/14 Synchronous machines
• CPC Class Codes: B60L 3/00 Electric devices on electrically-propelled vehicles for safety purposes; Monitoring operating variables, e.g. speed, deceleration or energy consumption methods or circuit arrangements for monitoring or controlling batteries or fuel cells B60L58/00
• CPC Class Codes: B60L 3/003 relating to inverters
• CPC Class Codes: B60L 50/51 characterised by AC-motors
• CPC Class Codes: B60L 58/15 Preventing overcharging
• 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

Abstract

A method and apparatus for driving an electric vehicle having a synchronous traction motor. A peak value of induced electromotive force of the synchronous motor at a maximum allowable rotating speed is set to a value which is lower than an allowable voltage of the smoothing capacitor of the inverter and lower than a maximum allowable voltage of the power switching elements composing the inverter. The synchronous motor is thus constructed so that a peak value V_0max of the maximum induced electromotive force at the maximum allowable rotating speed N₂ of the synchronous motor satisfies a relation of V_0max≦V_Cmax where V_Cmax is an allowable voltage of the smoothing capacitor.

Claims

1. Apparatus for driving an electric vehicle, comprising:

a permanent-magnet type synchronous traction motors

a battery;

an inverter for converting DC electric power from the battery into AC electric power which is supplied to the synchronous motor;

a smoothing capacitor connected in parallel to the inverter for smoothing the AC electric power; and

a PSM control unit for performing ON-OFF control of a plurality of power switching elements composing said inverter based on a torque reference and a motor current;

wherein an induced electromotive force of said synchronous motor is set so that a peak value V_0max of the maximum induced electromotive force at a maximum allowable rotating speed N₂ of said synchronous motor satisfies the condition V_0max≦

V_Cmax, V_Cmax being an allowable voltage of said smoothing capacitor; and

wherein V₀ obtained by the following equation satisfies said condition of V_0max;

2. A driving system for an electric vehicle according to claim 1, wherein said permanent-magnet type synchronous motor comprises a rotor having permanent magnets and a stator having windings (N_u, N_v, N_w) for U-, V-, W-phases, and the rotor and the stator of said synchronous motor are constructed so that:

3. A method for an electric vehicle propelled by a permanent-magnet type synchronous motor and having a battery, an inverter for converting DC electric power from the battery into AC electric power which is supplied to the synchronous motor, a smoothing capacitor connected in parallel to the inverter for smoothing the AC electric power, a PSM control unit for performing ON-OFF control of a plurality of power switching elements composing said inverter based on a torque reference and a motor current, said method comprising:

setting an induced electromotive force of said synchronous motor so that a peak value V_0max of the maximum induced electromotive force at a maximum allowable rotating speed N₂ of said synchronous motor satisfies the condition V_0max≦

V_Cmax, V_Cmax being an allowable voltage of said smoothing capacitor; and

wherein V₀ obtained by the following equation satisfies said condition of V_0max;

4. Method according to claim 3, wherein said permanent-magnet type synchronous motor comprises a rotor having permanent magnets and stator having windings (N_u, N_v, N_w) for U-, V-, W-phases, and the rotor and the stator of said synchronous motor are constructed so that: