Abstract: The control for an AC inverter includes a low voltage microcontroller referenced to ground potential and a waveform generator coupled to the microcontroller through a serial data link including optical isolation devices. The waveform generator floats at the negative bus potential of the DC source for the inverter. The waveform generator produces switching signals for the inverter under control of the microcomputer. The waveform generator, serial communications circuitry and other support circuits are all part of a single application specific integrated circuit.

Abstract: The inverter includes a low voltage microcontroller referenced to ground potential and a waveform generator coupled to the microcontroller through a serial data link including optical isolation devices. The waveform generator floats at the negative bus potential of the DC source for the inverter. The waveform generator produces switching signals for the inverter under control of the microcomputer. The waveform generator, serial communications circuitry and other support circuits are all part of a single application specific integrated circuit. Registers store control parameters from the microcontroller, and counters, a look up table and a state machine derive pulse width modulated switching commands to achieve motor control for a 60.degree. sector of motor field rotation and repeat the derivation of similar switching commands for each subsequent sector. A pulse director applies the pulses to the correct motor phases for a given sector.

Abstract: A DC braking system for an inverter-driven induction motor, (e.g., three-phase). When a braking command occurs, the normal gating sequence of the inverter stops. Mode 1 of the braking procedure starts. In Mode 1, two semiconductor phase switches of the group connected with one of the DC buses and the semiconductor switch of the third phase that is connected with the other DC bus are latched in a conducting state. The motor essentially receives DC current, which increases until it actuates a current limit device, clearing the latch. Then all six switches are turned off. That drives the motor current through the back-biased parallel diodes. The negative DC bus voltage is available to suppress motor current despite large motor speed voltages. The apparatus repeats the Mode 1 procedure for a predetermined time interval, after which Mode 2 of the braking procedure starts. In Mode 2, just as in Mode 1, two switches of one bus and one switch of another bus conduct until an overcurrent limit is reached.

Abstract: A field-oriented controller for a 3 phase induction motor is powered by a dc power source through a static inverter. Current reference signals are compared with current feedback to produce error signals. They are amplified by a proportional plus integral amplifier, whose output goes to a threshold comparator having negligible hysteresis. Flip-flops, through which the threshold comparators' gating signal outputs are fed, are clocked at a fixed frequency to introduce pseudo-randomness into the gating times. This reduces apparent acoustic noise of the motor. Asymmetrical anti-overlap delays for the gating signals are made long enough to serve also as the principal means for limiting the maximum frequency of gating. Locking circuitry overrides the proportional integral error signal in one phase at a time, and holds the inverter's gating in one switching state throughout the approximate middle 60.degree. interval of each phase. During each such 60.degree.

Abstract: A low cost, linear, low impedance tachometer/generator includes a stator and a rotor. The rotor includes a plurality of magnetic poles which alternate between first and second polarities, and the stator includes a plurality of first and second annular sets of planar laminated poles which are spaced apart, with the first set of poles having a first polarity and the second set of poles having a second polarity. An annular coil is disposed between the first and second sets of poles. The first set of poles is axially spaced apart and circumferentially offset one pole pitch about the axis of rotation from the second set of poles to effect simultaneous periodic alignment of the first set of poles on the stator with the plurality of poles on the rotor of the second polarity and the second set of poles on the stator with the plurality of poles on the rotor of the first polarity.

Abstract: A saturation condition regulator system for a power transistor which achieves the regulation objectives of a Baker clamp but without dumping excess base drive current into the transistor output circuit. The base drive current of the transistor is sensed and used through an active feedback circuit to produce an error signal which modulates the base drive current through a linearly operating FET. The collector base voltage of the power transistor is independently monitored to develop a second error signal which is also used to regulate base drive current. The current-sensitive circuit operates as a limiter. In addition, a fail-safe timing circuit is disclosed which automatically resets to a turn OFF condition in the event the transistor does not turn ON within a predetermined time after the input signal transition.

Abstract: A drivetrain (48) for an electric passenger vehicle (10) includes a battery (40) for energizing a single-phase A.C. traction motor (18) which drives a ground engaging wheel (12) through a multispeed transaxle (20). The motor is characterized by an external ferrite permanent magnet rotor (26) drivingly engaging an input shaft (32) of the transaxle. The motor is controlled by an inverter circuit (44) and a control circuit (46) which generates switch command signals to reciprocally actuate power transistors (56) and (62) within the inverter circuit as a function of operator demand, rotor position and rotor speed. The control circuit includes a motor positioning circuit (442) which toggles the motor current when the rotor speed falls below a predetermined level to dither the rotor about a park position for a predetermined period. A prestart rotor positioner (224) is provided to mechanically lock the rotor in its park position to ensure the availability of a high electrical starting torque.

Abstract: A drivetrain (48) for an electric passenger vehicle (10) includes a battery (40) for energizing a single-phase A.C. traction motor (18) which drives a ground engaging wheel (12) through a multi-speed transaxle (20). The motor is characterized by an external ferrite permanent magnet rotor (26) drivingly engaging an input shaft (32) of the transaxle. The motor is controlled by an inverter circuit (44) and a control circuit (46) which generates switch command signals to reciprocally actuate power transistors (56 and 62) within the inverter circuit as a function of operator demand, rotor position and rotor speed. The control circuit includes a motor positioning circuit (442) which toggles the motor current when the rotor speed falls below a predetermined level to dither the rotor about a park position for a predetermined period. A pre-start rotor positioner (224) is provided to mechanically lock the rotor in its park position to ensure the availability of a high electrical starting torque.

Abstract: A drivetrain for use with an electrically powered vehicle. The drivetrain has a source of electric power and an electric motor, including a rotor and a stator. A flag means rotates in a timed relationship with the rotor. A sensor means is mounted in a predetermined angular relationship with the stator and senses the presence of the flag means as the rotor turns. The sensor generates a signal representative of rotor position. An adjustment means selectively alters the angular relationship between the sensor means and the stator as a function of motor speed to effect a desired load angle and back EMF. Circuit means are provided to selectively energize the motor, in response to signals from the sensor means, as a function of rotor position.

Abstract: A method and system for providing assured start-up of a multi-pole permanent magnet electric motor from an at rest position. A vane is mounted on the rotational axis of the motor for rotation therewith. The vane includes a plurality of radially projecting portions each of which is maintained in a fixed angular relationship with a different one of the poles of the motor. A first and second pair of sensors are mounted in a fixed angular relationship with the stator of the motor, the second pair of sensors being spaced further apart than the first pair. The sensors generate a signal when one of the protecting portions of the vane passes through them. A control circuit receives input selectively from either the first sensor pair, under normal motor operation, or from the second pair of sensors when the motor is starting. The control circuit controls the direction of current flow through the motor in response to signals from the selected pair of sensors.

Abstract: An inverter (34) which provides power to an A.C. machine (28) is controlled by a circuit (36) employing PWM control strategy whereby A.C. power is supplied to the machine at a preselectable frequency and preselectable voltage. This is accomplished by the technique of waveform notching in which the shapes of the notches are varied to determine the average energy content of the overall waveform. Through this arrangement, the operational efficiency of the A.C. machine is optimized. The control circuit includes a micro-computer which calculates optimized machine control data signals from various parametric inputs and during steady state load conditions, seeks a best V/HZ ratio to minimize battery current drawn (system losses) from a D.C. power source (32). In the preferred embodiment, the present invention is incorporated within an electric vehicle (10) employing a 144 VDC battery pack and a three-phase induction motor (18).

Abstract: An inverter (34) which provides power to an A. C. machine (28) is controlled by a circuit (36) employing PWM control strategy whereby A. C. power is supplied to the machine at a preselectable frequency and preselectable voltage. This is accomplished by the technique of waveform notching in which the shapes of the notches are varied to determine the average energy content of the overall waveform. Through this arrangement, the operational efficiency of the A. C. machine is optimized. The control circuit includes a microcomputer and memory element which receive various parametric inputs and calculate optimized machine control data signals therefrom. The control data is asynchronously loaded into the inverter through an intermediate buffer (38). A base drive and overlap protection circuit is included to insure that both transistors of a complimentary pair are not conducting at the same time.