An inverter is disposed at a position on the upstream side relative to a compression mechanism along the flow of a refrigerant and the position cooled by the refrigerant. A motor is disposed at a position heated by the refrigerant compressed by the compression mechanism. A control device changes an upper limit value of a driving current supplied to the motor on the basis of at least one of first information relating to the temperature of the motor or second information relating to the temperature of the inverter.

Disclosed are an overload protection apparatus and method, and a storage medium, a compressor and an electric appliance. The apparatus includes: a first overload protection mechanism and a second overload protection mechanism, wherein the first overload protection mechanism is arranged to perform overload protection on the pressure of a compressor to be protected, and/or the second overload protection mechanism is arranged to perform overload protection on at least one of the temperature and the current of the compressor to be protected.

An operation controlling apparatus of a reciprocating compressor includes: a detector configured to detect a torque output by a motor of the reciprocating compressor, a rotation speed of the motor, a counter electromotive voltage of the motor, and a current applied to the motor; a controller configured to determine a mode switching time point for switching an operation mode of the reciprocating compressor based on the torque, the rotation speed, the counter electromotive voltage, and the current of the motor, and output a control signal for changing a wire ratio of the motor corresponding to the operation mode; and a driver configured to change the wire ratio of the motor based on the control signal and operate the reciprocating compressor in the operation mode among at least two operation modes.

A compressed air system for a motor vehicle with an air supply system includes an electric drive motor, which can be controlled for variable speed, an air compressor coupled to be driven by the electric drive motor, an electric power supply for supplying electric power to the electric drive motor, at least one air reservoir connected with the air compressor to receive air from the air compressor, an air utilization system connected to the air reservoir to receive air from the air reservoir, and a controller to control the speed of the electric drive motor. The controller controls the electric drive motor to determine its speed depending upon at least one of the following signals: a signal representing the activation status of an accelerator pedal of the vehicle, a signal representing the speed of the vehicle, a signal representing the temperature of the power supply, a signal representing the temperature of the electric drive motor, a signal representing the wetness level of the air compressed by the air compressor, a signal representing the load of the air compressor, a signal representing the running time of the air compressor, or a signal representing the status of the electric power supply.

A method for operating a speed-controlled fluid pump includes: providing an electrical control current for the fluid pump; providing a maximum value for the electrical control current, which maximum value corresponds to a maximum permissible pressure at an outlet side of the fluid pump; providing a threshold value for the control current, the threshold value corresponding to a further maximum permissible pressure at the outlet side of the fluid pump and is predefined in dependence upon at least one boundary condition, the threshold value being less than the maximum value for the electrical control current; and controlling the fluid pump with not more than the threshold value for the control current, if it has been determined that the at least one boundary condition holds, so as to limit the pressure at the outlet side of the fluid pump to a value provided for the at least one boundary condition.

There is provided a wobble plate piston water pump for use in a pressure washer and driven by a driving source, the water pump includes a pump body, a wobble plate, four or more pistons and a water passage defined by a water inlet and a water outlet. The driving source being electric powered and having a power consumption of less than or equal to a 15 ampere draw at 120 volts or 220 volts or the driving source being gas powered and having an engine displacement of less than or equal to 250 cubic centimetres.

An air compressor includes: a motor; a compression mechanism that is driven by the motor and that is configured to generate compressed air; a tank that is configured to store the generated compressed air; a load acquisition part that is configured to acquire a load applied to the compression mechanism; and a control part that is configured to control a rotation of the motor. The control part is configured to perform control for changing a TN characteristic of the motor in response to the load of the compression mechanism acquired by the load acquisition part.

A controller that controls an electric compressor, which is mounted to a vehicle and configures a two-stage compression refrigeration cycle device, has a deceleration section, an operation stop section, and a restart section. The deceleration section reduces a rotational speed of an electric motor by controlling an AC current which is output to the electric motor, when a two-stage compression mode, in which an intermediate-pressure refrigerant flows into the electric compressor from an intermediate-pressure port, is performed and an operation stop request to stop the electric compressor is made. The operation stop section stops the electric motor after the deceleration section reduces the rotational speed of the electric motor. The restart section restarts the electric compressor when the operation stop request is canceled after the operation stop section stops the electric compressor.

A motor drive control device has a control circuit that generates a drive control signal for controlling a rotational speed of a motor based on a speed command signal indicating a target rotational speed of the motor, and a motor driving unit that drives the motor based on the drive control signal. The control circuit performs speed feedback control for generating the drive control signal so that the rotational speed of the motor coincides with the target rotational speed when the target rotational speed is lower than a rotational speed threshold value, and generates the drive control signal based on a relationship between current flowing through the motor and a reference current value when the target rotational speed is higher than the rotational speed threshold value.

There is provided a wobble plate piston water pump for use in a pressure washer and driven by a driving source, the water pump includes a pump body, a wobble plate, four or more pistons and a water passage defined by a water inlet and a water outlet. The driving source being electric powered and having a power consumption of less than or equal to a 15 ampere draw at 120 volts or 220 volts or the driving source being gas powered and having an engine displacement of less than or equal to 250 cubic centimetres.