While an aircraft is mid-flight, a braking start point associated with a stoppable rotor is calculated where the stoppable rotor includes a first and second blade and the stoppable rotor is configured to rotate about a substantially vertical axis. A process to stop the stoppable rotor is started, while the aircraft is mid-flight, when the stoppable rotor reaches the braking start point, where the stoppable rotor is stopped with the first blade pointing forward and the second blade pointing backward.

Provided are a fan control method and a fan control system. The fan control method of the present invention includes the steps of predetermining a reliable operating temperature of a hard disk; creating a storing a corresponding relationship between an average hard disk temperature and a fan speed, and creating and storing a corresponding relationship between a hard disk temperature greater than the reliable operating temperature and a fan speed; reading actual temperatures of the plurality of hard disks; comparing the actual temperatures of the plurality of hard disks with the reliable operating temperature; computing an average temperature of the plurality of hard disks; and outputting a control signal to adjust the fan speed based on the stored corresponding relationship between an average hard disk temperature and a fan speed. Accordingly, the present invention may increase hard disk reliability and decrease power dissipation of a fan and system noise.

Provided are a fan control method and a fan control system. The fan control method of the present invention includes the steps of predetermining a reliable operating temperature of a hard disk; creating a storing a corresponding relationship between an average hard disk temperature and a fan speed, and creating and storing a corresponding relationship between a hard disk temperature greater than the reliable operating temperature and a fan speed; reading actual temperatures of the plurality of hard disks; comparing the actual temperatures of the plurality of hard disks with the reliable operating temperature; computing an average temperature of the plurality of hard disks; and outputting a control signal to adjust the fan speed based on the stored corresponding relationship between an average hard disk temperature and a fan speed. Accordingly, the present invention may increase hard disk reliability and decrease power dissipation of a fan and system noise.

Example computer-implemented methods, apparatuses, and systems are described for implementing split range control using Proportional-Integral (PI) control on a process. In some aspects, a feedback signal from the process is received. A proportional control is performed on the feedback signal to generate a first control output while an integral control is performed on the feedback signal to generate a second control output. A first valve of the process is controlled based on the first control output while a second valve of the process is controlled based on the second control output. The second valve has a valve diameter larger than a valve diameter of the first valve.

A servo control apparatus includes a subtractor configured to calculate a difference between a first command value for controlling a servo motor, and a first detection value from the servo motor; an integral term creation unit configured to create an integral term based on an output of the subtractor; an internal division processing unit configured to internally divide the first command value; a subtractor configured to calculate a difference between an output of the internal division processing unit and the first detection value; a proportional term creation unit configured to create a proportional term based on the subtractor; and a adder configured to add an output of the integral term creation unit and an output of the proportional term creation unit, in which a calculation period calculated by the proportional term creation unit is shorter than a calculation period calculated by the integral term creation unit.

A servo control apparatus includes a subtractor configured to calculate a difference between a first command value for controlling a servo motor, and a first detection value from the servo motor; an integral term creation unit configured to create an integral term based on an output of the subtractor; an internal division processing unit configured to internally divide the first command value; a subtractor configured to calculate a difference between an output of the internal division processing unit and the first detection value; a proportional term creation unit configured to create a proportional term based on the subtractor; and a adder configured to add an output of the integral term creation unit and an output of the proportional term creation unit, in which a calculation period calculated by the proportional term creation unit is shorter than a calculation period calculated by the integral term creation unit.

A method may include: (i) based on an error between a setpoint value and a measured process value, determining an integrated error indicative of a time-based integral of the error; (ii) based on the error, determining a differential error indicative of a time-based derivative of the error; (iii) based on the integrated error and the error, generating a proportional-integral output driving signal; (iv) based on the differential error and the error, generating a proportional-differential output driving signal; (v) determining whether the differential error is stable; (vi) responsive to determining that the differential error is stable, generating a driving signal for controlling a plant based on the proportional-differential output driving signal and independent of the proportional-integral output driving signal; (vii) responsive to determining that the differential error is unstable, generating the driving signal for controlling the plant based on the proportional-differential output driving signal and the proportional-integral output driving signal.

A method may include: (i) based on an error between a setpoint value and a measured process value, determining an integrated error indicative of a time-based integral of the error; (ii) based on the error, determining a differential error indicative of a time-based derivative of the error; (iii) based on the integrated error and the error, generating a proportional-integral output driving signal; (iv) based on the differential error and the error, generating a proportional-differential output driving signal; (v) determining whether the differential error is stable; (vi) responsive to determining that the differential error is stable, generating a driving signal for controlling a plant based on the proportional-differential output driving signal and independent of the proportional-integral output driving signal; (vii) responsive to determining that the differential error is unstable, generating the driving signal for controlling the plant based on the proportional-differential output driving signal and the proportional-integral output driving signal.

A photovoltaic power plant includes a photovoltaic inverter that converts direct current generated by solar cells to alternating current. The output of the photovoltaic inverter is provided to a point of interconnection to a power grid. A meter at the point of interconnection may be read to detect the output of the photovoltaic inverter at the power grid. The photovoltaic power plant includes a plant controller with a state machine. The plant controller is configured to adjust setpoints of the photovoltaic inverter to control the output of the photovoltaic power plant. The plant controller is also configured to soft start and soft stop automatic voltage regulation (AVR) of the photovoltaic power plant to prevent perturbing the AVR.

A photovoltaic power plant includes a photovoltaic inverter that converts direct current generated by solar cells to alternating current. The output of the photovoltaic inverter is provided to a point of interconnection to a power grid. A meter at the point of interconnection may be read to detect the output of the photovoltaic inverter at the power grid. The photovoltaic power plant includes a plant controller with a state machine. The plant controller is configured to adjust setpoints of the photovoltaic inverter to control the output of the photovoltaic power plant. The plant controller is also configured to soft start and soft stop automatic voltage regulation (AVR) of the photovoltaic power plant to prevent perturbing the AVR.