A variable frequency motor drive comprises a converter including a rectifier having an input for connection to an AC power source and converting the AC power to DC power. A DC bus is connected to the rectifier circuit. At least one bus capacitor is across the DC bus. An inverter receives DC power from the DC bus and converts the DC power to AC power to drive a motor. A controller is operatively connected to the converter. The controller comprises a speed control controlling the inverter responsive to a speed command to maintain a desired motor speed. A speed foldback control measures DC bus ripple voltage and regulates the speed command responsive to the measured DC bus ripple voltage.

Systems and techniques detecting a reverse current are disclosed. An apparatus comprises a switching circuit coupled to a load and a reference node. The switching circuit may be capable of conducting a reverse current from the reference node to the load when a voltage at the load is lower than a voltage at the reference node. A voltage source has a first terminal coupled to the load, a second terminal configured to follow a voltage at the load, and produces a voltage proportional to a voltage drop across the switching circuit. A comparator circuit is coupled to compare a voltage at the second terminal of the voltage source to the voltage at the reference node and configured to indicate when the reverse current has a magnitude greater than a predetermined threshold.

Charging control techniques for a vehicle including an engine that drives an alternator configured to charge a battery of the vehicle comprise modeling a fuel consumption of the alternator for each load level across a range of alternator loads using an engine torque model and a set of operating parameters of the engine, determining an energy output from the alternator for each load level across the range of alternator loads, calculating a cost-to-charge metric based on the modeled alternator fuel consumption and the determined alternator energy output for each duty cycle across a range of duty cycles of the alternator, determining an optimal cost-to-charge from the calculated cost-to-charge metrics, determining a target cost-to-charge metric based on a state of charge of the battery, and operating the alternator accordingly at an optimal duty cycle based on the metrics and current engine operating conditions.

A power conversion device includes first and second inverters connectable to at least one of first and second coil groups, a first separation relay circuit connected to the first inverter, a second separation relay circuit connected to the second inverter, a third separation relay circuit connected between the first separation relay circuit and the first coil group, a fourth separation relay circuit connected between the second separation relay circuit and the second coil group, and n connection lines to, for each phase, connect n nodes between the first and third separation relay circuits and n nodes between the second and fourth separation relay circuits, where n is an integer of 3 or more.

A power conversion device includes: a rectifying unit rectifying an AC voltage output from an AC power supply; a booster circuit boosting an output voltage of the rectifying unit; a control unit causing the booster circuit to perform synchronous rectification; and a smoothing capacitor smoothing an output voltage of the booster circuit. The booster circuit is constituted by connecting a plurality of chopper circuits in parallel to each other, the chopper circuits each including an upper arm switching element and a lower arm switching element connected in series to a reactor connected to the rectifying unit, and the control unit generates a drive pulse causing the upper arm switching element to be turned on when a reverse current flows through the upper arm switching element.

A controller for an electric motor system is provided. The electric motor system includes a DC power supply, a power converter, a smoothing capacitor, a three-phase AC motor, and a current sensor. The controller includes an electronic control unit. The electronic control unit is configured to control the power converter such that an inter-terminal voltage of the smoothing capacitor matches a first reference value. The first reference value is a value which is determined as the inter-terminal voltage of the smoothing capacitor when a phase current is equal to a second reference value. The electronic control unit is configured to correct a detection value of the current sensor so as to decrease a difference between the detection value and the second reference value when the inter-terminal voltage matches the first reference value and the detection value does not match the second reference value.

A configurable motor system includes a housing having an electrical power input and an interface receptacle, an electric motor received in the housing, an output shaft rotationally driven by the electric motor, a motor control circuit received in the housing and configured to control power delivery from the electrical power input to the electric motor and a modular interface in communication with the motor control circuit through the interface receptacle. The modular interface is configured to receive one or more user inputs and to direct the motor control circuit to control power delivery to the electric motor based on the user input and based on pre-programmed instructions corresponding to a tool to which the motor system is attached.

A configurable motor system includes a housing having an electrical power input and an interface receptacle, an electric motor received in the housing, an output shaft rotationally driven by the electric motor, a motor control circuit received in the housing and configured to control power delivery from the electrical power input to the electric motor and a modular interface in communication with the motor control circuit through the interface receptacle. The modular interface is configured to receive one or more user inputs and to direct the motor control circuit to control power delivery to the electric motor based on the user input and based on pre-programmed instructions corresponding to a tool to which the motor system is attached.

The invention relates to an operating state circuit for actuating an inverter (3), which supplies an n-phase electrical machine (5) with an n-phase supply voltage via phase connections (4a, 4b, 4c), wherein n1, comprising an evaluation device (6) which is connected to the phase connections (4a, 4b, 4c) of the inverter (3) and which is configured to detect output voltages of the inverter (3) to the phase connections (4a, 4b, 4c) and to determine a speed of the electrical machine (5) on the basis of the detected output voltages, and an actuating device (7) which is coupled to the evaluation device (6) and which is configured to switch to an idle state or an active short-circuit in dependence on the determined speed of the inverter (3).

The power conversion device includes a power-supply shunt resistance provided between an inverter and the negative-voltage side of a DC power supply, respective-phase lower-arm shunt resistances provided between the power-supply shunt resistance and respective-phase lower-arm switching elements, a first overcurrent detection unit performing overcurrent detection on a current that flows through the power-supply shunt resistance on the basis of a power-supply shunt-resistance voltage, and a second overcurrent detection unit performing overcurrent detection on each current that flows through the respective-phase lower-arm shunt resistances on the basis of respective-phase lower-arm voltages, wherein overcurrent detection is performed on each phase current using either one of the overcurrent detection result of the first overcurrent detection unit and the overcurrent detection result of the second overcurrent detection unit.