The present disclosure is constructed on the prior art inverter architecture, a pulse code width modulation (PCWM). This is an open loop motor control system without sensing its rotor position. The present disclosure employs a closed loop method to track the optimum efficiency motor operating point directly. A bench load test is conducted to gather information for an AI type control, which includes both load angle vs. voltage command charts and power factor vs. voltage command charts, with load levels as parameters for certain frequency command ranges. This way, the optimum efficiency motor operating points are generated a priori. The AI type control is mechanized to track the optimum efficiency motor operating points.

A motor control circuit with power factor correction capabilities that optimizes the voltage and current load applied to an electric motor for different motor speeds and torque levels. The preferred motor control circuit includes a power factor correction circuit and a step down conversion circuit through which current passes before it reaches the motor. A microprocessor preferably monitors the current supplied to the motor and the motor's speed. If the microprocessor determines that the current supplied to the motor is too high, it can reduce the level of current by either using a pulse width modulation (PWM) digital-to-analog control circuit to instruct the power factor correction circuit to reduce current or it can use a PWM digital control circuit to instruct the step down conversion circuit to reduce current. An output voltage limiter circuit can be used to detect the voltage of current supplied to the motor and turn off current to the motor if the voltage is above a predetermined level.

A converter device includes a rectifier circuit to rectify an AC voltage output from an AC power supply, a booster circuit including a plurality of reactors, a plurality of switching elements, and a plurality of backflow prevention elements to boost an output voltage of the rectifier circuit, a smoothing capacitor to smooth an output voltage of the booster circuit, a bus-current detection circuit to detect a value of a current that flows between the rectifier circuit and the booster circuit, a first filter circuit having a first filter time constant, a second filter circuit having a second filter time constant shorter than the first filter time constant, and a control unit to control an operation of the switching elements as a current value detected by the bus-current detection circuit is input to the control unit via the first filter circuit and the second filter circuit.

A motor control system includes a plurality of inverters each configured to be connected to a corresponding one of a plurality of motors, a plurality of current samplers coupled to the plurality of inverters, respectively, and each configured to sample a phase current of a corresponding one of the plurality of motors to generate a phase current signal for the corresponding one of the plurality of motors, and an operation controller including an analog-digital (AD) sampling circuit. The operation controller is configured to synchronously generate a plurality of triangular carrier signals each corresponding to one of the plurality of motors, and sample the phase current signals of the plurality of motors in a time sharing manner through the AD sampling circuit in rising half cycles or falling half cycles of the plurality of triangular carrier signals, respectively. The half cycles of the triangular carrier signals for sampling the phase current signals of the plurality of motors are staggered in time from each other.

A method of performing scalar-based control of a motor connected to a power converter via at least one passive electrical reactance component, wherein the method includes: estimating a motor current at terminals of the motor to thereby obtain an estimated motor current, and controlling the power converter based on the estimated motor current.

In a method for detecting a motor phase fault of a motor arrangement, the motor phases of which are connected to a drive circuit having a DC voltage intermediate circuit and an inverter. A motor phase voltage at at least one of the motor phases with respect to a reference potential is captured while the inverter is switched off; and a voltage profile of the captured motor phase voltage is used to determine whether there is a motor phase fault on one of the motor phases of the motor arrangement.

A drive circuit for driving an electronically commutated motor contains a DC voltage intermediate circuit, and an inverter which is connected to the latter and has a bridge circuit containing a plurality of circuit breakers, to which the motor phases of a motor configuration containing the motor can be connected. For detecting an insulation fault in the motor configuration, a positive or negative circuit breaker of the inverter is switched on, while all other circuit breakers of the inverter are switched off before all circuit breakers of the inverter are switched off. A motor phase voltage of a selected motor phase of the motor phases with respect to a reference potential is then captured, while all circuit breakers of the inverter remain switched off in order to determine whether there is an insulation fault on the motor phase on a basis of a voltage profile of the motor phase voltage.

A device for power factor correction can include a converter housing having an inner surface; a first converter substrate mounted on the inner surface of the converter housing; a second converter substrate mounted on another surface of first converter housing opposite to the inner surface; and a housing cover covering the first converter substrate and coupled to an upper surface of the converter housing, in which the second converter substrate includes a first surface having a first region including a source pad, and a second region including a drain pad spaced apart from the source pad, the source pad including a source pad extension portion extending into the second region; and a second surface including a heat dissipation pad for communicating heat from the source and drain pads to an outside of the device, in which the first region of the second converter substrate overlaps with the another surface of first converter housing, and the second region of the second converter substrate faces the housing cover without overlapping with the first converter substrate.

A power converter includes: a rectifying and boosting unit that rectifies first alternating-current power supplied from a commercial power supply and boosts a voltage of the first alternating-current power; a capacitor connected to an output end of the rectifying and boosting unit; an inverter to convert power output from the rectifying and boosting unit and the capacitor into second alternating-current power, and output the second alternating-current power to a device; and a control unit that reduces a current flowing through the capacitor by controlling the rectifying and boosting unit and by controlling the inverter such that the inverter outputs, to the device, the second alternating-current power containing a ripple dependent on a ripple of power flowing from the rectifying and boosting unit into the capacitor. The control unit controls in accordance with a load state.

A converter device includes a rectifier circuit to rectify an AC voltage output from an AC power supply, a booster circuit including a plurality of reactors, a plurality of switching elements, and a plurality of backflow prevention elements to boost an output voltage of the rectifier circuit, a smoothing capacitor to smooth an output voltage of the booster circuit, a bus-current detection circuit to detect a value of a current that flows between the rectifier circuit and the booster circuit, a first filter circuit having a first filter time constant, a second filter circuit having a second filter time constant shorter than the first filter time constant, and a control unit to control an operation of the switching elements as a current value detected by the bus-current detection circuit is input to the control unit via the first filter circuit and the second filter circuit.