Electric motor control device
View Patent ↗An electric motor control device includes a current vector controller that follows a target command value for controlling an electric current of the motor by separating the current into a d-axis current and q-axis current orthogonal to each other. The motor control device further includes a driver for driving the motor, a phase-angle generator a phase-angle command generator for generating a phase-angle command β* based on difference Δv* between an absolute value |v*| of a voltage command supplied from the current vector controller to the driver and a given reference value V lmt , a d-axis current command generator for generating d-axis current command id* based on a sine value of the phase-angle command β*, and a q-axis current limiter for setting a limit value of q-axis current command iq* based on a cosine value of the phase-angle command β*. This structure allows canceling a voltage saturation, and driving the motor stably with high output around a voltage saturation region even if a target command value exceeding an output limit of the motor is input.
1. An electric motor control device equipped with a current vector controller that follows a target command value for controlling an electric current of a motor by separating the current into a d-axis current and a q-axis current orthogonal to each other, the electric motor control device comprising:
a driver for driving the motor;
a phase-angle command generator for generating a phase-angle command based on a difference between an absolute value of a voltage command supplied from the current vector controller to the driver and a given reference value;
a d-axis current command generator for generating a command of the d-axis current based on a sine value of the phase-angle command; and
a q-axis current limiter for setting a limit value of a command of the q-axis current based on a cosine value of the phase-angle command.
2. The electric motor control device of claim 1 , wherein the d-axis current command generator outputs the command of the d-axis current, where the command takes a value found by combining a d-axis current vector and q-axis current vector together, and a upper limit value of the combined value, namely a maximum current value, is multiplied by the sine value of the phase-angle command, and then a sign of a product of the multiplication is changed to an opposite one, this resultant value is output as the command of the d-axis current,
wherein the q-axis current limiter sets a limit value of the command of the q-axis current, where the limit value takes a value found by multiplying the cosine value of the phase-angle command by the maximum current value.
3. The electric motor control device of claim 2 further comprising a d-axis current limiter for limiting the command of the d-axis current to a given limit value smaller than the maximum current value.
4. The electric motor control device of claim 1 further comprising a filter for smoothing a target command value supplied from outside or the command of the q-axis current.
5. The electric motor control device of claim 1 , wherein the phase-angle command generator generates the phase-angle command using a q-axis component of the voltage command instead of using the absolute value of the voltage command supplied to the driver.
6. The electric motor control device of claim 5 , wherein the given reference value of the phase-angle command generator is corrected by using a d-axis component of the voltage command supplied to the driver.
7. The electric motor control device of claim 3 , wherein the d-axis current limiter sets the given limit value at 0 (zero).
8. The electric motor control device of claim 4 , wherein the d-axis current limiter sets the given limit value at 0 (zero).
9. The electric motor control device of claim 5 , wherein the d-axis current limiter sets the given limit value at 0 (zero).
10. The electric motor control device of claim 6 , wherein the d-axis current limiter sets the given limit value at 0 (zero).