A system for detecting a decrease in or loss of an input phase to a motor. A power rectifier rectifies and combines three input voltages to produce an output voltage to power the motor. A PFC circuit manages the power flowing to the motor. A sensing circuit located between the power rectifier and the PFC senses a voltage level of the power rectifier's output voltage. Alternatively, a sensing rectifier is connected before the power rectifier, and the sensing circuit senses the voltage level of the sensing rectifier's output voltage. A microprocessor compares the sensed voltage level to a threshold voltage level which is indicative of the decrease in or loss of one of the three input voltages, and if the former drops below the latter, then the microprocessor sends a signal to either shut off the motor or cause the PFC circuit to reduce the power flowing to the motor.

According to the disclosure, the electric motor is electrically commutated with the aid of circuitry, in which the phase current experiences a zero crossing at certain time points per motor phase. Owing to the inductive load portion, the time of said zero crossing of a phase current occurs at different times to the time of the zero crossing that would arise with purely ohmic loads. Without a faulty load condition, the time of said zero crossing is within an expected value range (e.g., expected time window) which can be determined by the circuitry, the ambient conditions and by diverse motor parameters. According to the method, during occurrence of the high-side and/or low-side phase connection predetermined in the circuitry, it is determined whether and when the current through the switched-on high-side of low-side switch becomes greater or smaller than a predeterminable threshold, in a particular case in the vicinity of the zero crossing, wherein said time measurement can extend in the case of a PWM control, if required, over one or more PWM cycles.

In view of the problem that an existing technique can detect a failure in an arm circuit for each phase and continue motor drive by only a normal phase, but a brake torque is generated due to a closed circuit of the faulty phase, an inverter apparatus for polyphase AC motor drive is provided that includes: a first power supply switching device in a power supply line to an inverter circuit; a second power supply switching device for each phase in the arm circuit of the inverter circuit, and a motor relay switching device in an output path from each phase, wherein the parasitic diodes of the first power supply switching device and second power supply switching device have directional characteristics different from each other, which prevent generation of a closed circuit.

A ground fault immune power and data delivery system for downhole sensors is connected to a downhole motor via a three-phase power cable. An AC power supply and sensor data module are electrically connected to one of two conductors (phases) at a time selected from the three conductors (phases) to provide power and data signals to the downhole sensors. If a ground fault is detected on one of the two connected phases, an isolation module isolates the grounded phase and switches to the ungrounded connected phase to continue transmitting power and data signals. A frequency of AC power supply, data communication frequencies and a switching frequency of a drive controlling the downhole motor are orthogonal to each other in order to mitigate interference. Surface-to-downhole communication can occur by adjusting voltage, frequency and/or phase of AC power supply controlled by a processor.

[Problem]_0 An object of the present invention is to provide an electric power steering apparatus that has a 3-shunt control function to perform a 3-shunt PWM-control for raising a reliability of the apparatus and for improving a stability, and a 1-shunt control function to perform a 1-shunt PWM-control so as to continue an assist control when the 3-shunt control function is damaged.

[Means for Solving the Problem] The electric power steering apparatus according to the present invention, having: a 3-shunt control function to perform a 3-shunt PWM-control with a first 3-phase detected current values based on down-stream 3-shunt; a 1-shunt control function to perform a 1-shunt PWM-control with a second 3-phase detected current values based on down-stream 1-shunt; and a switching function to switch from the 3-shunt control function to the 1-shunt function when a failure of current detection circuit system in relation to the first 3-phase detected current values is detected.

A robot system includes: a robot; a three-phase inverter having a high side switch and a low side switch connected in series; a power line electrically connecting a connection point between the high side switch and the low side switch to a stator winding of a motor; a short circuit path that electrically connects at least two lines of the power line; a brake switch arranged in the short circuit path to change the short circuit path to an open state or a closed state; a break detector that detects a disconnection of the power line; and an operation part that operates the brake switch from the open state to the closed state, when the break detector detects the disconnection.

An apparatus for detecting a motor failure may include: a first motor failure detector configured to apply a reference voltage for failure detection to a motor, and then detect a changed voltage; a first motor power switch and a second motor power switch configured to switch both terminal voltages applied to drive the motor; a gate amplifier configured to apply a gate signal for controlling the turn on/off of the first and second motor power switches; and a controller configured to diagnose a failure of the motor controlled in one way, on the basis of voltages detected by the first and second motor power switches and the first motor failure detector, respectively.

An electric motor controller for controlling an electric motor and methods of determining a loss of phase condition for at least one phase of three-phase input power provided to an electric motor controller are provided. The controller is configured to obtain phase sample data representing an input power electrical characteristic for at least one phase of three-phase power received by the controller and receive direct current (DC) bus data representing a measured DC bus electrical characteristic. The controller is also configured to calculate a ratio between the phase sample data and the DC bus data, and determine that a loss of phase condition exists for a phase of the three-phase power when the ratio exceeds a predetermined threshold.

An inverter control device for controlling a rotating electric machine drive device that drives an alternating current rotating electric machine and includes an inverter and a DC link capacitor, the inverter being connected to a DC power supply via a contactor, being connected to the rotating electric machine, and performing power conversion between direct current and three-phase alternating current, the DC link capacitor smoothing a DC link voltage, which is a DC-side voltage of the inverter, and the inverter control device performing switching control on switching elements that form the inverter.

A method for operating an electric machine assembly is provided. The electric machine assembly includes an electric machine having a first set of windings and a second set of windings. The method includes: operating the electric machine in a partial phase mode, wherein operating the electric machine in the partial phase mode comprises: powering a first set of windings to provide a net zero current in the first set of windings while maintaining one phase of the first set of windings in a non-conducting condition; and powering a second set of windings to provide a net zero current in the second set of windings while maintaining one phase of the second set of windings in a non-conducting condition.