Abstract: This method for controlling an asynchronous electrical motor (32) of a compressor system (10), comprises:—connecting (100) a capacitor bank (50) of the compressor system (10) in parallel with a first electrical motor (32) of the compressor system, this connection comprising connecting capacitors (52, 54, 56) of the capacitor bank (50) to windings of the stator of the first motor (32), by operating a switch unit (60) of the capacitor bank connected to an internal power bus (12);—starting (102) the first asynchronous electrical motor (32), by providing an input electrical current to the windings of the first motor (32) from the internal power bus (12);—disconnecting (108) the capacitor bank (50) from said first motor (32) once said motor (32) has started, this disconnection comprising disconnecting said capacitors (52, 54, 56) from the windings of the motor (32).

Abstract: This method for controlling asynchronous electrical motors of a compressor system, comprises: —receiving an order to start a first asynchronous electrical motor and a second asynchronous electrical motor of a compressor system; —unloading said first and second motors, by operating respectively a first load control unit of the first motor and a second load control unit of the second motor, in order to reduce the mechanical load associated to said motors; —starting the first motor and, only once the first motor is running at nominal speed, starting the second motor, —loading both the first and second electrical motor only once the second motor has started and is running at nominal speed, by operating the first load control unit and the second load control unit, in order to increase the mechanical load associated to said motors.

Abstract: A compressor unit (2) for use in a refrigeration circuit, comprises at least two compressors (8, 10); and a common variable frequency drive (6), configured to be connected to a three phase grid voltage supply (4); each compressor (8, 10) having an inlet port (12) configured to be in refrigerant communication, via a suction line, with an outlet of an evaporator; an outlet port (14) configured to be in refrigerant communication, via a pressure line, to an inlet of a condenser; a compressor motor (18), particularly an alternating current induction motor, with a three phase supply line (32-1, 32-2); a power modulation means (24) for controlling the power of the compressor (8, 10) according to its load needs; wherein each compressor (8, 10) is switchable, independently from the respective other compressor(s) (8, 10), to be connected, during start-up and acceleration of the respective compressor (8, 10), to the common variable frequency drive (6), and to be connected, during rated-speed operation of the respective

Abstract: This method for controlling asynchronous electrical motors of a compressor system, comprises: —receiving an order to start a first asynchronous electrical motor and a second asynchronous electrical motor of a compressor system; —unloading said first and second motors, by operating respectively a first load control unit of the first motor and a second load control unit of the second motor, in order to reduce the mechanical load associated to said motors; —starting the first motor and, only once the first motor is running at nominal speed, starting the second motor, —loading both the first and second electrical motor only once the second motor has started and is running at nominal speed, by operating the first load control unit and the second load control unit, in order to increase the mechanical load associated to said motors.

Abstract: This method for controlling an asynchronous electrical motor (32) of a compressor system (10), comprises:—connecting (100) a capacitor bank (50) of the compressor system (10) in parallel with a first electrical motor (32) of the compressor system, this connection comprising connecting capacitors (52, 54, 56) of the capacitor bank (50) to windings of the stator of the first motor (32), by operating a switch unit (60) of the capacitor bank connected to an internal power bus (12);—starting (102) the first asynchronous electrical motor (32), by providing an input electrical current to the windings of the first motor (32) from the internal power bus (12);—disconnecting (108) the capacitor bank (50) from said first motor (32) once said motor (32) has started, this disconnection comprising disconnecting said capacitors (52, 54, 56) from the windings of the motor (32).

Abstract: A compressor unit (2) for use in a refrigeration circuit, comprises at least two compressors (8, 10); and a common variable frequency drive (6), configured to be connected to a three phase grid voltage supply (4); each compressor (8, 10) having an inlet port (12) configured to be in refrigerant communication, via a suction line, with an outlet of an evaporator; an outlet port (14) configured to be in refrigerant communication, via a pressure line, to an inlet of a condenser; a compressor motor (18), particularly an alternating current induction motor, with a three phase supply line (32-1, 32-2); a power modulation means (24) for controlling the power of the compressor (8, 10) according to its load needs; wherein each compressor (8, 10) is switchable, independently from the respective other compressor(s) (8, 10), to be connected, during start-up and acceleration of the respective compressor (8, 10), to the common variable frequency drive (6), and to be connected, during rated-speed operation of the respective

Abstract: The invention relates to an electrical subsystem to power a vehicle refrigeration system. The electrical subsystem includes an AC drive electrically coupled to a high voltage DC bus. The AC drive provides “refrigeration compressor AC power” responsive to a cooling demand. The electrical subsystem also includes a “low voltage DC bus”. The low voltage DC bus powers a plurality of low voltage refrigeration components including refrigeration fans. A microcontroller sets the compressor AC voltage and the compressor AC frequency. A method of preventing vehicle refrigeration system compressor stall includes the step of limiting the electrical AC power to the compressor such that the AC voltage does not droop causing a compressor stall. Also, an electrical subsystem for powering a compressor in a vehicle refrigeration system includes “V/f” operating information for the compressor, and a microcontroller commands the AC voltage and the AC frequency to the compressor.