Motor controller

1. A motor controller comprising:

a current detection section that detects a current flowing between a power source and an inverter circuit generating a voltage applied to a coil of a motor;

an overload determination value output section that outputs an overload determination value used to determine whether or not the motor is overloaded;

an overload determination section that determines the motor to be overloaded in a case in which a current value detected by the current detection section is equal to or greater than the overload determination value; and

a rotation speed control section that controls to reduce the motor rotation speed to a specific speed in a case in which the overload determination section has determined the motor to be overloaded;

a thermistor that has one terminal to which a voltage is applied across a resistor, has another terminal connected to ground, and has a resistance value that changes with temperature; and

a connection section that connects together the one terminal of the thermistor and an output terminal of the overload determination value output section, so as to divide the overload determination value voltage with increasing temperature.

2. The motor controller of claim 1 , further comprising a resistor connected in parallel with the thermistor.

3. The motor controller of claim 2 , wherein:

the thermistor has characteristics of a resistance value that decreases with increasing temperature; and

the connection section is a resistor with one terminal connected to the one terminal of the thermistor, and another terminal connected to the overload determination value output section.

4. The motor controller of claim 2 , wherein:

the thermistor has characteristics of a resistance value that decreases with increasing temperature; and

the connection section is a temperature variable resistor that has characteristics of a resistance value that decreases with increasing temperature, that is connected to the one terminal of the thermistor and to an output terminal of the overload determination value output section, and that decreases the voltage of the overload determination value output from the output terminal of the overload determination value output section with increasing temperature.

5. The motor controller of claim 4 , further comprising a resistor connected in parallel with the temperature variable resistor.

6. The motor controller of claim 5 , wherein the temperature variable resistor is a thermistor.

7. The motor controller of claim 4 , wherein the temperature variable resistor is a thermistor.

8. The motor controller of claim 2 , further comprising:

an overcurrent determination value output section that outputs an overcurrent determination value exceeding the overload determination value; and

an overcurrent determination section that determines the motor to be in an overcurrent state in a case in which a current value detected by the current detection section is equal to or greater than the overcurrent determination value; and

wherein the rotation speed control section stops rotation of the motor for a specific duration in a case in which the overcurrent determination section has determined the motor to be in an overcurrent state.

9. The motor controller of claim 1 , wherein:

the thermistor has characteristics of a resistance value that decreases with increasing temperature; and

the connection section is a resistor with one terminal connected to the one terminal of the thermistor, and another terminal connected to the overload determination value output section.

10. The motor controller of claim 9 , further comprising:

an overcurrent determination value output section that outputs an overcurrent determination value exceeding the overload determination value; and

an overcurrent determination section that determines the motor to be in an overcurrent state in a case in which a current value detected by the current detection section is equal to or greater than the overcurrent determination value; and

wherein the rotation speed control section stops rotation of the motor for a specific duration in a case in which the overcurrent determination section has determined the motor to be in an overcurrent state.

11. The motor controller of claim 1 , wherein:

the thermistor has characteristics of a resistance value that decreases with increasing temperature; and

the connection section is a temperature variable resistor that has characteristics of a resistance value that decreases with increasing temperature, that is connected to the one terminal of the thermistor and to an output terminal of the overload determination value output section, and that decreases the voltage of the overload determination value output from the output terminal of the overload determination value output section with increasing temperature.

12. The motor controller of claim 11 , further comprising a resistor connected in parallel with the temperature variable resistor.

13. The motor controller of claim 12 , wherein the temperature variable resistor is a thermistor.

14. The motor controller of claim 12 , further comprising:

an overcurrent determination value output section that outputs an overcurrent determination value exceeding the overload determination value; and

an overcurrent determination section that determines the motor to be in an overcurrent state in a case in which a current value detected by the current detection section is equal to or greater than the overcurrent determination value; and

wherein the rotation speed control section stops rotation of the motor for a specific duration in a case in which the overcurrent determination section has determined the motor to be in an overcurrent state.

15. The motor controller of claim 11 , wherein the temperature variable resistor is a thermistor.

16. The motor controller of claim 15 , further comprising:

an overcurrent determination value output section that outputs an overcurrent determination value exceeding the overload determination value; and

an overcurrent determination section that determines the motor to be in an overcurrent state in a case in which a current value detected by the current detection section is equal to or greater than the overcurrent determination value; and

wherein the rotation speed control section stops rotation of the motor for a specific duration in a case in which the overcurrent determination section has determined the motor to be in an overcurrent state.

17. The motor controller of claim 11 , further comprising:

an overcurrent determination value output section that outputs an overcurrent determination value exceeding the overload determination value; and

an overcurrent determination section that determines the motor to be in an overcurrent state in a case in which a current value detected by the current detection section is equal to or greater than the overcurrent determination value; and

wherein the rotation speed control section stops rotation of the motor for a specific duration in a case in which the overcurrent determination section has determined the motor to be in an overcurrent state.

18. The motor controller of claim 1 , further comprising:

an overcurrent determination value output section that outputs an overcurrent determination value exceeding the overload determination value; and

an overcurrent determination section that determines the motor to be in an overcurrent state in a case in which a current value detected by the current detection section is equal to or greater than the overcurrent determination value; and

wherein the rotation speed control section stops rotation of the motor for a specific duration in a case in which the overcurrent determination section has determined the motor to be in an overcurrent state.

19. The motor controller of claim 1 , further comprising:

an overcurrent determination value output section that outputs an overcurrent determination value exceeding the overload determination value; and

an overcurrent determination section that determines the motor to be in an overcurrent state in a case in which a current value detected by the current detection section is equal to or greater than the overcurrent determination value; and

wherein the rotation speed control section stops rotation of the motor for a specific duration in a case in which the overcurrent determination section has determined the motor to be in an overcurrent state.