Unique apparatuses, methods, and systems of opposing, limiting, and/or preventing undesired or un-commanded compressor rotation are disclosed. One exemplary embodiment is an HVACR system comprising a variable frequency drive configured to drive an electric motor to rotate a screw compressor or scroll compressor. A controller is configured to monitor various aspects of the system and to control the drive. When a condition indicative of potential undesired or un-commanded compressor rotation is identified, the controller commands the variable frequency drive to control the motor to limit and preferably prevent compressor rotation. One technique comprises shorting switches of the drive to a DC bus rail to allow back EMF induced current in the motor windings to be dissipated through winding resistance thus providing a damping force. Another technique comprises controlling the inverter to insert a DC current into the motor to cause the motor to align to and hold a particular position.

A method of controlling an air conditioner including activating a refrigeration cycle by driving an compressor; detecting a high pressure and a low pressure when the refrigeration cycle is activated; adjusting an operating frequency of the compressor based on the detected high pressure or low pressure of the refrigeration cycle; determining a current load of an inside space through a load detecting unit; determining a load level of the inside space by comparing the current load with a reference load; and determining the operating frequency of the compressor based on the determined load level.

A refrigerator and a method for controlling the same are disclosed. The refrigerator may minimize the size and material cost of the control system by controlling the internal temperature and the speed of a compressor using a thermostat used in the conventional low-capacity/low-cost refrigerator without using a system controller equipped with various sensors (internal sensors and/or external sensors) capable of controlling the internal temperature. In addition, since an inverter controller capable of controlling a BLDC compressor estimates the internal/external temperature based on operation information of the compressor, and determines the internal load, it may save energy and reduce vibrations and noise, which are the largest disadvantages of a constant-speed compressor, thereby improving satisfaction of the consumer. In addition, the BLDC compressor may be started and operated stably by applying a differentiated algorithm of the inverter controller.

An abnormality determination device for a transporting refrigeration apparatus includes a determination unit that determines an abnormality of the transporting refrigeration apparatus installed on a container. In pre-trip inspection that is conducted before the container is loaded on a transporting device, a test operation is performed for test operating modes. The pre-trip inspection is conducted multiple times. The abnormality determination device is configured to obtain at least part of time series test data related to a same one of the test operating modes in the pre-trip inspection. The determination unit is configured to determine whether the transporting refrigeration apparatus has an abnormality based on a change trend of the time series test data related to a same one of the test operating modes when the pre-trip inspection is conducted multiple times, and when there is no abnormality, estimate an abnormality occurrence time.

A power conversion apparatus includes: an inverter to drive a motor, using a first carrier signal; an inverter connected in parallel to the inverter, to drive a motor, using a second carrier signal; respective phase lower arm shunt resistors to detect a first current flowing inside the inverter; respective phase lower arm shunt resistors to detect a second current flowing in the inverter; and a control unit to control the inverters. A phase difference is set between the first carrier signal and the second carrier signal to prevent a detection period for the first current in the first carrier signal and a detection period for the second current in the second carrier signal from overlapping each other when the inverters are controlled.

An air conditioner controller and a safety protection circuit for the same are provided. The air conditioner controller includes a central processing unit, a drive unit, a safety locking unit and a protection detection unit, where the central processing unit is configured to output an air conditioner control signal; the air conditioner motor drive unit is configured to receive a drive control signal output from the safety locking unit and the detection protection signal, and output a drive signal to control an operation of an air conditioner motor; the safety locking unit is configured to receive the detection protection signal and the air conditioner control signal, output the drive control signal, and control the air conditioner control signal to be transmitted or cut off based on the detection protection signal output from the protection detection unit.

A compressor driving apparatus and an air conditioner including the same, whereby the compressor driving apparatus includes a capacitor connected to a DC terminal, an inverter, including a plurality of three-phase switching devices, to convert DC power from the capacitor into AC power to drive a compressor motor, an output current detector to detect output current flowing in the motor, and a controller to output a switching control signal for controlling the inverter based on the output current, wherein the controller performs control such that some of the three-phase switching devices in the inverter are turned on or off in a compressor preheating mode.

A determination device includes a refrigerant circuit, an operation determination unit, and a refrigerant determination unit. The refrigerant circuit is made of a compressor, a condenser, an expansion mechanism, and an evaporator that are circularly connected. In a refrigeration cycle operation in accordance with a quantity of heat required by the condensers or the evaporators, the operation determination unit determines whether the refrigeration cycle operation can be normally carried out or not. Upon determination that the refrigeration cycle operation cannot be normally carried out, the refrigerant determination unit determines whether a refrigerant in the refrigerant circuit is regenerable or not, based on a result of the determination. Thus the determination device is provided by which an effort involved with determination as to whether the refrigerant is regenerable or not can be reduced.

A method for determining a level of refrigerant charge in a vapor compression system having a compressor, a condenser, an expansion device and an evaporator operatively connected in serial relationship in a refrigerant flow circuit having a refrigerant, includes receiving information indicative of at least one of a compressor torque or compressor current; and determining whether the refrigerant charge is within a defined tolerance or whether the refrigerant is to be added or recovered in response to the receiving of the information.

A control method and system for a resonant linear compressor applied for controlling the capacity of a cooling system. The method includes: a) reading a reference operation power (P.sub.ref) of the motor of the compressor; b) measuring an operation current (i.sub.MED); c) measuring an operation voltage of a control module of the compressor; d) calculating an input power (P.sub.MED) of the motor as a function of the operation current (i.sub.MED) and of the operation voltage; e) comparing the input power (P.sub.MED) with the reference operation power (P.sub.ref); f) if the reference operation power (P.sub.ref) is higher than the input power (P.sub.MED), then increase an operation voltage of the compressor (UC); g) if the reference operation power (P.sub.ref) is lower than the input power (P.sub.MED), then decrease the operation voltage of the compressor (UC).