Method and system for motor speed control

A system for remotely controlling the speed of the motor, the system including:

• a central control unit, a motor control unit and a network connecting the control units, wherein:
• the central control unit includes:
• a variable frequency transmitter, arranged to send a timing signal over the network which represents the desired speed of the motor;
• and
• the motor control unit includes:
• the motor;
• and
• an analogous phase locked loop connected to a network and arranged to receive a timing signal from that network and to control the speed of the motor according to that timing signal,
• wherein the analogous phase locked loop is arranged to generate an error signal which is the difference between the timing signal received from the network and an output signal of a counter which is incremented according to the speed of the motor, and to adjust the speed of the motor according to the error signal.

A method of remotely controlling the speed of a motor, the motor forming part of an analogous phase-locked loop, the method including the steps of:

• sending, over a network, a timing signal which represents desired speed of the motor to the analogous phase-locked loop;
• detecting the speed of the motor as a local oscillator signal;
• receiving said timing signal;
• comparing the phase of said timing signal and said oscillator signal to generate an error signal;
• and
• adjusting the speed of the motor according to the error signal.