Drive control apparatus for electric car

1. A drive control apparatus for an electric car wherein a three-phase AC voltage is generated by a VVVF inverter, and a linear induction motor is driven by the three-phase AC voltage, the drive control apparatus comprising:

current detection means for outputting instantaneous value information of a three-phase AC current which flows from the VVVF inverter to the linear induction motor on the basis of the three-phase AC voltage;

three-phase/two-phase conversion means for converting the instantaneous value information of the three-phase AC current into two-phase current information and outputting the two-phase current information;

axle rotational-frequency information output means for outputting axle rotational-frequency information which represents a rotational frequency of an axle of the electric car;

wheel-diameter correction information output means including wheel-diameter information calculation means for calculating wheel-diameter calculation information representing a wheel diameter of the electric car on the basis of the two-phase current information, and configured so as to be capable of outputting the wheel-diameter calculation information as wheel-diameter correction information;

synchronizing-frequency calculation means for calculating synchronizing frequency information representing a synchronizing frequency of the linear induction motor on the basis of the axle rotational-frequency information and the wheel-diameter correction information; and

vector calculation control means for outputting a control command for the VVVF inverter, on the basis of a torque command, the two-phase current information and the synchronizing frequency information.

2. The drive control apparatus for an electric car as defined in claim 1 , wherein the wheel-diameter correction information output means further includes selection output means, and the selection output means receives in addition to the wheel-diameter calculation information, a wheel-diameter data output from wheel-diameter data means disposed in a driver's cabin, and it selects either of a state where the wheel-diameter data output is outputted as the wheel-diameter correction information, and a state where the wheel-diameter calculation information is outputted as the wheel-diameter correction information.

3. The drive control apparatus for an electric car as defined in claim 2 , wherein the selection output means selects the state where the wheel-diameter data output is outputted as the wheel-diameter correction information, in a case where the wheel-diameter data output has been normally received, whereas it selects the state where the wheel-diameter calculation information is outputted as the wheel-diameter correction information, in a case where the wheel-diameter data output is not normally received.

4. The drive control apparatus for an electric car as defined in claim 3 , wherein the selection output means further receives wheel-diameter default information, and it selects the state where the wheel-diameter calculation information is outputted as the wheel-diameter correction information, when a predetermined requirement has been met in the case where the wheel-diameter data output is not normally received, whereas it selects a state where the wheel-diameter default information is outputted as the wheel-diameter correction information, when the predetermined requirement is not met.