Abstract: An apparatus and method for controlling sinusoidal currents in inductive loads during zero-crossing to reduce distortion. The apparatus and method utilizes first and second PWM signals during a single PWM cycle to apply opposite voltage signals to obtain a net desired voltage across the inductive load. The voltage applied to the load is compared with a threshold and, when the applied voltage is greater than the threshold, normal PWM signals are applied to the load, and when the applied voltage is less than the threshold, an adjusted voltage formed of first and second PWM signals is applied to the load.

Abstract: A control system for an electric motor used to provide mechanical power to a power steering system in a vehicle. The motor is of the two-phase type with an independent winding for each phase, or of the three-phase type with two independent stator windings. Two inverters are provided, one for each winding. Each inverter provides AC current to run the motor. If a fault is detected in an inverter or its stator winding, current is terminated to that inverter, and the motor is run using the other winding. In addition, if the vehicle battery is installed with incorrect polarity, components within the inverters can be destroyed. The invention detects the incorrect polarity, and blocks current to the inverters.

Abstract: An apparatus and method for controlling sinusoidal currents in inductive loads during zero-crossing to reduce distortion. The apparatus and method utilizes first and second PWM signals during a single PWM cycle to apply opposite voltage signals to obtain a net desired voltage across the inductive load. The voltage applied to the load is compared with a threshold and, when the applied voltage is greater than the threshold, normal PWM signals are applied to the load, and when the applied voltage is less than the threshold, an adjusted voltage formed of first and second PWM signals is applied to the load.

Abstract: A control system for a brushless DC motor, preferably used in a power steering system in a vehicle. Presently delivered torque is computed without measuring currents in the motor. A demanded torque signal is received, and a torque error signal is produced. The torque error signal is modified by an inertial torque component, if the motor is accelerating. In response to the modified error signal, the control system first attempts to increase motor torque by increasing motor voltage, if that is possible, without increasing magnetic field which is parallel with the magnetic field of the rotor. If that is not possible, then motor voltage is held fixed, and the magnetic field just mentioned is increased.

Abstract: An improved stator for an electric motor. In one form of the invention, each stator slot in a stator contains only coils of a single phase. Thus, if a short occurs in that coil, no other phase is present in the slot for the short to connect with. In another form of the invention, pre-formed coils are constructed, having hollow cores. Each coil is inserted over a stator tooth, and then additional structure is added to form a rim from which the teeth extend, somewhat like spokes on a wheel.

Abstract: A control system for an electric motor. Field Oriented Control, FOC, uses a digital control system, and attempts to maintain the rotating stator magnetic field ninety degrees ahead of the rotor field, in order to maximize torque. However, if a three-phase motor is used, which is very common, large amounts of computation are required, to convert from a three-phase coordinate system to an orthogonal coordinate system. The invention replaces the three-phase motor with a two-phase motor, which has been found to impose certain additional costs, but also provides benefits.

Abstract: A fault-handling system for a 2-phase motor. When an electric motor is used for power assist in a steering system in a vehicle, malfunctions can cause loss of assist, and detectable vibration. The invention utilizes a 2-phase motor in such an application, and implements alternate modes of operation when certain malfunctions occur, thereby maintaining the assist function in situations wherein the function would otherwise be lost or reduced.

Abstract: An electric motor having reduced cogging torque. Motors have stator teeth separated by a slot, or space, which is filled with air and/or copper. The magnetic field present in the space is reduced, compared to that present in the iron cores. Thus, when the rotor rotates, it sees a changing magnetic field as it passes a tooth face, then a slot, and then a neighboring tooth face. This change can produce a force or cogging torque in the motor. The invention changes the geometry of the tooth face and slot to reduce variation of reluctance and increase overall flux of the stator.

Abstract: System for reducing electronic noise in a radio in a vehicle. Pulse Width Modulated, PWM, motors used in a vehicle receive pulses of electric current. These pulses have a Fourier spectrum of harmonics which can be picked up by a radio in the vehicle, causing the radio to produce unwanted noise. The invention reduces the noise by continually varying the base frequency of the PWM pulses, to thereby vary the spectrum of the noise. This varying spectrum is more difficult for humans to detect.