Abstract: A screw compressor (100), comprising a screw rotor (110) and a spool valve (120). The screw rotor (110) comprises a suction head end (111) and an exhaust tail end (112). Gas is sucked in from the suction head end (111) and compressed gas is discharged from the exhaust tail end (112). The spool valve (120) comprises a working side (125) for sealing a compression chamber of the screw rotor (110). The working side (125) comprises a spool valve head end (121) and a spool valve tail end (122) and can do a reciprocating motion along the axis direction of the screw rotor (110). When the spool valve (120) moves to a suction capacity adjusting position (240), the spool valve head end (121) is located at the inner side of the suction head end (111) of the screw rotor (110), and a suction capacity adjusting distance (D2) is formed between the spool valve head end (121) and the suction head end (111) so that the suction capacity of the screw compressor is adjusted.

Abstract: A screw compressor (100), comprising a screw rotor (110) and a spool valve (120). The screw rotor (110) comprises a suction head end (111) and an exhaust tail end (112). Gas is sucked in from the suction head end (111) and compressed gas is discharged from the exhaust tail end (112). The spool valve (120) comprises a working side (125) for sealing a compression chamber of the screw rotor (110). The working side (125) comprises a spool valve head end (121) and a spool valve tail end (122) and can do a reciprocating motion along the axis direction of the screw rotor (110). When the spool valve (120) moves to a suction capacity adjusting position (240), the spool valve head end (121) is located at the inner side of the suction head end (111) of the screw rotor (110), and a suction capacity adjusting distance (D2) is formed between the spool valve head end (121) and the suction head end (111) so that the suction capacity of the screw compressor is adjusted.

Abstract: The present application provides a control system and method for a permanent magnet synchronous traction and transmission system. A The control system comprises a sampling unit and a controller; the sampling unit collecting an operation excitation current and an operation torque current, a input capacitor voltage and a rotor frequency; the controller acquires a target torque instruction issued to the traction and transmission system, calculates a target excitation current value and a target torque current value, and generates an excitation current regulation value and a torque current regulation value; a regulation unit is configured to generate a torque current regulation value according to the target torque current value and an operation torque current value and generate a target modulation ratio and a modulation frequency according to the excitation current regulation value and the torque current regulation value output from the regulation unit and finally output a PWM modulation wave control signal.

Abstract: The present application provides a control system and method for a permanent magnet synchronous traction and transmission system. A The control system comprises a sampling unit and a controller; the sampling unit collecting an operation excitation current and an operation torque current, a input capacitor voltage and a rotor frequency; the controller acquires a target torque instruction issued to the traction and transmission system, calculates a target excitation current value and a target torque current value, and generates an excitation current regulation value and a torque current regulation value; a regulation unit is configured to generate a torque current regulation value according to the target torque current value and an operation torque current value and generate a target modulation ratio and a modulation frequency according to the excitation current regulation value and the torque current regulation value output from the regulation unit and finally output a PWM modulation wave control signal.