Motor speed controller

A speed controller used in a control loop of a motor, comprising:

• a first comparator configured to comparing a measured speed of the motor with a first predetermined speed value, and output a first signal in response to the measured speed equaling or exceeding the first predetermined speed value, or output a second signal in response to the received speed being equal to or less than the predetermined speed value;
• a second comparator configured to comparing an instruction speed of the motor with a second predetermined speed value, and output a third signal in response to the instruction speed equaling or exceeding the second predetermined speed value, or output a fourth signal in response to the instruction speed being equal to or less than the second predetermined speed value;
• a processing device comprising:
• a first input configured to receive a speed difference between the instruction speed and the measured speed;
• a second input configured to receive the first signal or the second signal from the first comparator;
• a third input configured to receive the third signal or the fourth signal from the second comparator;
• and
• an output configured to output a first proportional value in response to receiving the first signal and the third signal, output a second proportional value in response to receiving the first signal and the fourth signal, output a third proportional value in response to receiving the second signal and the third signal, or output a fourth proportional value in response to receiving the second signal and the fourth signal, wherein each of the second, third, and fourth proportional values is less than the first proportional value;
• and
• an arithmetic logical unit (ALU) comprising:
• a first input configured to receive one of the first, second, third, and fourth proportional values;
• and
• an output configured to output an instruction current to the control loop by calculating the received proportional value according to a predetermined calculation rule.