A method of operating an electric motor is disclosed. The method includes: determining a d-axis resistance of an electric motor and a Q-axis resistance of the electric motor as a function of a bulk current; determining a d-axis inductance of the electric motor and a Q-axis inductance of the electric motor as a function of the bulk current; generating an estimated flux of the electric motor based on the d-axis resistance of the electric motor, the Q-axis resistance of the electric motor, the d-axis inductance of the electric motor, and the Q-axis inductance of the electric motor; generating an estimated angle of the electric motor based on the estimated flux of the electric motor; and, based on the estimated angle of the electric motor, controlling switching of an inverter that powers the electric motor.

The present invention provides for a control system for a compressor assembly of an heating, ventilation, and air conditioning (HVAC) system. A control assembly comprises a controller for varying the capacity of a compressor unit of the compressor assembly. The controller determines a first pressure of the compressor unit based on a first operating state of the compressor unit.

A refrigeration system having a refrigeration unit (22) for providing temperature conditioned air to a temperature controlled space, an engine (26) and an electric generation device (24) driven by the engine, is provided with a battery system (28) for supplying electric power. A method of operating the transport refrigeration includes, during a high cooling demand mode, operating the engine (26) to drive the electric generation device (24) for supplying electric power and simultaneously employing the battery system (28) for supplying electric power to jointly power the plurality of power demand loads (50, 42, 46, 48) of the refrigerant unit.

The purpose of the present invention is to install an economizer having a sufficient internal volume in a compact turbo refrigeration apparatus specifically using a low-pressure refrigerant, and reduce refrigerant pressure loss and enhance efficiency in the turbo refrigeration apparatus. The turbo refrigeration apparatus according to the present invention comprises: a turbo compressor which compresses a refrigerant; a condenser which condenses the compressed refrigerant; a control valve which causes the condensed refrigerant to expand; an evaporator which causes the expanded refrigerant to evaporate; and an economizer which is installed in such a manner as to be sandwiched between the condenser and the evaporator, and separates the refrigerant expanded by the control valve into gas and liquid. The economizer is installed adjacent to a curved wall, having a drum shell shape, of the condenser and/or the evaporator, the curved wall being shared with the structural wall of the economizer. The economizer has a height (H) greater than the maximum width (W) thereof when viewed in the longitudinal direction thereof.

A synchronous motor control device includes a voltage detector, a current detector, an inverter main circuit, and an inverter control unit. The inverter control unit includes: a phase current reproduction unit that reproduces a direct current into phase currents flowing to a permanent magnet synchronous motor; a current coordinate transformation unit that transforms the reproduced phase current into current on a control coordinate axis of a rotating coordinate system; a current control unit that calculates a voltage command value of the permanent magnet synchronous motor in such a manner that the current on the control coordinate axis equals a specific value; and a limiter unit that limits the value of the voltage command value.

Motor drive device (30) includes brushless DC motor (5) that drives a load and speed controller (8) that decides a PWM ON ratio for performing PWM control on brushless DC motor (5). The motor drive device further includes PWM ON ratio increasing-reducing unit (9) that increases/reduces the PWM ON ratio in accordance with a driving speed of brushless DC motor (5) and drive unit (10) that performs PWM control for driving brushless DC motor (5) in accordance with the PWM ON ratio decided by PWM ON ratio increasing-reducing unit (9). PWM ON ratio increasing-reducing unit (9) sets the PWM ON ratio to a ratio equal to or lower than the PWM ON ratio decided by speed controller (8) in an interval in which the driving speed of brushless DC motor (5) is lower than a predetermined speed, and sets the PWM ON ratio to a ratio equal to or higher than the PWM ON ratio decided by speed controller (8) in an interval in which the driving speed is higher than the predetermined speed.

Provided is a refrigerator. The refrigerator may include a power supply unit configured to power the refrigerator using commercial power, a battery coupled to the power supply unit and configured to supply auxiliary power to the refrigerator, a power detection unit coupled to the power supply unit and the battery and configured to detect whether power is being supplied from the power supply unit, a driving unit to provide cold air, and a controller configured to control an operational mode of the driving unit based on the detection at the power detection unit. When the power supply unit is supplying power, the driving unit may be controlled to operate in a normal operation mode, and when the power supply unit is not supplying power, the driving unit may be controlled to operate in a power failure operation mode and to control the power to be supplied from the battery.

Provided is a refrigerator. The refrigerator may include a power supply unit configured to power the refrigerator using commercial power, a battery coupled to the power supply unit and configured to supply auxiliary power to the refrigerator, a power detection unit coupled to the power supply unit and the battery and configured to detect whether power is being supplied from the power supply unit, a driving unit to provide cold air, and a controller configured to control an operational mode of the driving unit based on the detection at the power detection unit. When the power supply unit is supplying power, the driving unit may be controlled to operate in a normal operation mode, and when the power supply unit is not supplying power, the driving unit may be controlled to operate in a power failure operation mode and to control the power to be supplied from the battery.

A variable capacity compressor (100), a cooler (200) including same, and a method and system for controlling a variable capacity compressor are disclosed. An electronic control (50), a thermostat (30) and a power source (10) are disclosed, the power source including a neutral terminal and a phase terminal, the thermostat including a first terminal and a second terminal, and the electronic control including a phase feed input and a neutral feed input, the neutral terminal of the power source electrically connected to the neutral feed input of the electronic control and the phase terminal of the power source electrically connected to the first terminal of the thermostat, the second terminal of the thermostat connected electrically to the phase feed input of the electronic control, the thermostat configured to feed and un-feed selectively the electronic control, the electronic control activating and deactivating selectively the compressor and controlling its cooling capacity.

A variable refrigerant package air conditioner is shown that is easy to install in new construction with a unique base that causes collected mixture that overflows to drain outside the building. A control system is shown that has motors and compressor that are pulse width modulated so the air conditioner is infinitely variable while maintaining the highest possible power factor. Dehumidification of outside air occurs as it is mixed with inside air. By gradually approaching a temperature set point and even reheating after dehumidification, moisture is removed from the room.