Control device of rotation detector
A control device of a rotation detector inputs an AC signal to an excitation coil and detects a rotation angle on the basis of a signal obtained by a detection coil. The control device includes: a controller that can output a plurality of excitation signals having a predetermined voltage; and a signal generation unit that generates the AC signal on the basis of the plurality of excitation signals output from the controller. In addition, the control device includes a voltage dividing circuit that is interposed between the controller and the signal generation unit and decreases the predetermined voltage of the plurality of excitation signals by a resistor to transmit the voltage to the signal generation unit.
1. A control device of a rotation detector that inputs an AC signal to an excitation coil on a stator and detects a rotation angle on the basis of a signal obtained by a detection coil on a rotor, the control device of a rotation detector comprising:
a controller that can output a plurality of excitation signals having a predetermined voltage, wherein each of the plurality of excitation signals is a pulse width modulation (PWM) signal;
a signal generation unit that generates the AC signal on the basis of the plurality of excitation signals output from the controller; and
a voltage dividing circuit that is interposed between the controller and the signal generation unit and decreases the predetermined voltage of the plurality of excitation signals by a resistor to transmit the voltage to the signal generation unit,
wherein the controller includes a first port and a second port that output the plurality of excitation signals,
the voltage dividing circuit includes a first conducting wire having a first resistor interposed and extending from the first port, a second conducting wire having a second resistor interposed and that has a resistance value different from that of the first resistor, extending from the second port, and merging with the first conducting wire, and a third conducting wire connecting a junction of the first conducting wire and the second conducting wire and the signal generation unit,
the resistance value of the first resistor is twice the resistance value of the second resistor,
the resistance value of the first resistor is set in a manner that the voltage after a voltage drop in the first resistor is one-third of the predetermined voltage in a state where only the first port is outputting the PWM signal, and
the voltage of the PWM signal passing through the third conducting wire is changed in multiple stages at equal intervals.
2. The control device of a rotation detector according to claim 1 , wherein
the rotation detector is an inductive type resolver that inputs the AC signal of a predetermined amplitude to the excitation coil and detects the rotation angle on the basis of an amplitude-modulated signal obtained by the detection coil.
3. The control device of a rotation detector according to claim 1 , wherein
the rotation detector is a modulation wave type resolver that inputs an amplitude-modulated AC signal to the excitation coil and detects the rotation angle on the basis of a phase-modulated signal obtained by the detection coil.
4. The control device of a rotation detector according to claim 1 , wherein
the voltage of the PWM signal passing through the third conducting wire is changed in four stages at equal intervals.