Motor control apparatus, motor control circuit, and method thereof

1. A motor control apparatus for controlling a motor based on an output from a sensor comprising:

a storage unit storing a value according to an excitation power supply to excite the sensor;

a first PWM (Pulse Width Modulation) output unit outputting a PWM output signal having a pulse width modulated to have a duty ratio corresponding to a value stored to the storage unit;

a second PWM output unit for amplitude adjustment for modulating a pulse width to have a duty ratio corresponding to an amplitude of the excitation power supply;

and

a filter input with the PWM output signal from the PWM output unit,

wherein the sensor is supplied with the excitation power supply based on an output from the filter.

2. The motor control apparatus according to claim 1 ,

wherein the amplitude of the excitation power supply is adjusted by the PWM output unit for amplitude adjustment.

3. The motor control apparatus according to claim 1 , further comprising:

a driving signal generation unit generating a driving signal to drive the motor; and

a counter provided in the driving signal generation unit operating in accordance with a clock signal and,

wherein the PWM output unit outputs the PWM signal according to a counter value of the counter.

4. The motor control apparatus according to claim 3 , further comprising:

a register storing a value to be compared with the counter value of the counter,

wherein the motor control apparatus changes a duty ratio of the PWM output signal depending on a comparison result between the counter value and the value stored to the register.

5. A motor control method for controlling a motor based on an output from a sensor comprising:

storing a value based on an excitation power supply for exciting the sensor;

outputting a first PWM (Pulse Width Modulation) output signal having a duty ratio corresponding to the stored value;

outputting a PWM output signal for amplitude adjustment for adjusting an amplitude of the excitation power supply; and

generating an excitation power supply for exciting the sensor according to the PWM output signal.

6. The motor control method according to claim 5 , further comprising:

generating the excitation power supply of the sensor according to the PWM output signal for amplitude adjustment and the PWM output signal.

7. The motor control method according to claim 5 , further comprising:

generating a driving signal for driving the motor based on a counter value of a counter; and

generating the PWM output signal based on the counter value of the counter.

8. The motor control method according to claim 7 , further comprising:

comparing a value stored to the a register with the counter value of the counter; and

changing a duty ratio of the PWM output signal depending on a result of the comparison.

9. A motor control circuit for controlling a motor based on an output from a sensor comprising:

an excitation power supply generation unit generating an excitation power supply for exciting the sensor; and

a feedback control unit generating a control signal in response to a sensor output signal outputted from the sensor according to an excitation power supply from the excitation power supply generation unit,

wherein the motor control circuit controls an amplitude of the excitation power supply to be supplied to the sensor according to the control signal, and

wherein a second control signal is generated to change the amplitude of the excitation power supply.

10. The motor control circuit according to claim 9 , wherein in case the feedback control detects that the sensor output signal does not reach a specified amplitude, the feedback control unit outputs the second control signal to the excitation power supply generation unit to change the amplitude of the excitation power supply.

11. The motor control circuit according to claim 10 , wherein the excitation power supply generation unit comprises a level shift circuit and changes the amplitude of the excitation power supply according to the control signal.

12. The motor control circuit according to claim 9 , wherein the excitation power supply generation unit further comprises:

a first PWM (Pulse Width Modulation) output circuit generating an excitation power supply based on data from a waveform table;

a second PWM output circuit provided separately from the first PWM output circuit for outputting a PWM signal according to the control signal from the feedback control unit; and

a circuit changing the amplitude by combining outputs from the first and the second PWM output circuits.

13. The motor control circuit according to claim 12 , wherein the first PWM output circuit is comprised of a PWM output circuit for motor mounted to a driving signal generation unit for generating a driving signal for driving a motor.

14. The motor control circuit according to claim 13 , further comprising:

an unit outputting a carry signal having a specified bits of a counter mounted to the PWM output circuit for motor;

a comparator comparing a value from the waveform table with an output value of the counter and outputting a result of the comparison; and

a circuit generating a PWM signal from the carry signal and the comparison result.

15. The motor control circuit according to claim 12 , wherein the circuit for changing the amplitude is comprised of an EX-NOR circuit.

16. The motor control circuit according to claim 9 , wherein the sensor is comprised of a resolver for outputting information of a rotation angle of the motor as the sensor output signal by being supplied with an excitation power supply.

17. The motor control circuit according to claim 9 , wherein the feedback control unit comprises:

an expected amplitude value storing circuit for storing an expected amplitude value of the sensor output signal outputted from the sensor;

wherein the expected amplitude value storing circuit compares the expected amplitude value with a maximum amplitude value of the sensor output signal outputted from the sensor, and controls the excitation power supply generation unit to change the amplitude of the excitation power supply corresponding to the difference between the expected amplitude value and the sensor output signal outputted by the sensor.

18. The motor control circuit according to claim 17 ,

wherein the excitation power supply generation unit comprises a level shift circuit, and

wherein the expected amplitude value storing circuit controls the level shift circuit to change the amplitude of the excitation power supply corresponding to the difference between the expected amplitude value and the sensor output signal outputted by the sensor.