초록 ▼

In a brushless DC motor system, an RMS value of an input current of a voltage-fed inverter (702) is detected by a current transformer (705) and an RMS value detector circuit (706). A rotation speed of a brushless DC motor (703) is detected based on a cycle of a position signal outputted by a positio

In a brushless DC motor system, an RMS value of an input current of a voltage-fed inverter (702) is detected by a current transformer (705) and an RMS value detector circuit (706). A rotation speed of a brushless DC motor (703) is detected based on a cycle of a position signal outputted by a position sensor circuit (704). Then, in response to the RMS value of the input current and the rotation speed, the phase of the inverter output voltage relative to the phase of the motor counter-electromotive voltage is set to a phase at which the motor efficiency comes generally to a peak, and a switching command to the voltage-fed inverter (702) is generated. With this constitution, when the applied voltage waveform is controlled only by the voltage-fed inverter in response to the rotor-position detection signal, the motor attains high-efficiency operation without involving any increase in cost and yet regardless of load conditions.

대표청구항 ▼

[ We claim:] [1.] A method for controlling a brushless DC motor comprising the steps of:detecting a rotation speed and a rotor position of a brushless DC motor driven by a voltage-fed inverter;detecting an input current of the voltage-fed inverter; andsetting a switching command to the voltage-fed i

[ We claim:] [1.] A method for controlling a brushless DC motor comprising the steps of:detecting a rotation speed and a rotor position of a brushless DC motor driven by a voltage-fed inverter;detecting an input current of the voltage-fed inverter; andsetting a switching command to the voltage-fed inverter such that the phase of the inverter output voltage relative to the phase of the motor counter-electromotive voltage is set to a specified phase at which motor efficiency comes generally to a peak, in response to the detected rotation speed and the detected input current. [14.] A motor system comprising:a rotor;a stator having armature coils connected in a three-phase star configuration;a resistor circuit connected in three-phase star configuration in parallel to said armature coils;an inverter for switching a voltage pattern to be applied to said armature coils; andcontrol means for controlling an output of said inverter so that a specified efficiency is obtained, based on a neutral-point voltage of said armature coils, said control means including a level decision means for determining a relationship between a signal representing a voltage difference between neutral points of said armature coils and said resistor circuit and a target value. The motor system according to claim 14, wherein the specified efficiency is a peak efficiency. The motor system according to claim 14, further comprising:rotor-position sensor means for detecting a relative rotor position between said rotor and said stator, and thereby outputting a position signal,wherein said control means further includes phase correction means for adjusting a time interval from the position signal to a switching of the voltage pattern so that the level of the voltage difference signal becomes the target value, based on a decision result of said level decision means. The motor system according to claim 15, further comprising:rotor-position sensor means for detecting a relative rotor position between said rotor and said stator, and thereby outputting a position signal,wherein said control means further includes; phase correction means for adjusting a time interval from the position signal to a switching of the voltage pattern so that the level of the voltage difference signal becomes the target value, based on a decision result of said level decision means. The motor system according to claim 14, wherein said level decision means determines a relationship between a level of an integral signal derived by integrating the signal representing the voltage difference between the neutral point of said armature coils and the neutral point of said resistor circuit and the target value and said control means further including phase correction means (T1,T2,41,42) for adjusting a time interval from the position signal to a switching of the voltage pattern so that the level of the integral signal becomes the target value, based on a decision result of the level decision means. The motor system according to claim 15, wherein said level decision means determines a relationship between a level of an integral signal derived by integrating the signal representing the voltage difference between the neutral point of said armature coils and the neutral point of said resistor circuit and the target value at which a peak efficiency is obtained and said control means further including phase correction means (T1,T2,41,42) for adjusting a time interval from the position signal to a switching of the voltage pattern so that the level of the integral signal becomes the target value, based on a decision result of the level decision means.