Apparatus for controlling brushless motors in response to switching transistor temperature
AssigneeZexel Corporation
InventorShinichi Ohi
Life of this patent
Estimating the term…
Abstract
A control apparatus for controlling a rotational speed of a brushless direct current motor in accordance with a duty cycle of a pulse signal for controlling by the use of switching transistors exciting current flowing pulsewise through exciting coils of the motor. The apparatus has a detector for detecting the temperature of the transistors and the frequency of the pulse signal is determined in response to the detector so as not to overheat the transistors. Thus, smooth rotation can be obtained in a way that ensures that the transistors will not heat excessively.
Claims18
A control apparatus for controlling a brushless direct current motor comprising:
- a position sensor for detecting a rotational position of a rotor of the motor;
- switching circuit means for selectively supplying exciting current to a plurality of coils located on the stator side of the motor;
- setting means for producing a first signal for setting a preselected set rotational speed of the motor;
- detecting means for producing a second signal related to a temperature of a switching transistor or transistors of said switching circuit means;
- generating means responsive to the first and second signals for generating a pulse signal, the duty cycle of the pulse signal being established by the first signal to control the speed of said motor, said generating means comprising determining means responsive to the second signal for establishing the frequency of said pulse signal so that the frequency changes as the temperature of the switching transistor(s) changes to reduce power consumption and prevent overheating of said switching transistors;
- and,
- control means responsive to said position sensor and pulse signal for controlling said switching circuit means to supply the exciting current necessary for rotating the motor to the coils in a pulse pattern according to the pulse signal generated by said generating means.
A control apparatus for controlling a rotational speed of a brushless direct current motor in accordance with a duty cycle of a control pulse signal for controlling by the use of switching transistors exciting current flowing pulsewise through exciting coils provided on a stator of the motor, said apparatus comprising;
- detecting means for detecting a temperature of at least one of the switching transistors;
- and
- determining means responsive to the detecting means for varying the control pulse signal frequency so as not to overheat the switching transistors.
A control apparatus for controlling a brushless direct current motor comprising:
- a position sensor for detecting a rotational position of a rotor of the motor;
- switching circuit means for selectively supplying exciting current to a plurality of coils located on the stator side of the motor;
- setting means for setting a preselected set rotational speed of the motor;
- detecting means for electrically detecting a temperature of a switching transistor or transistors of said switching circuit means;
- generating means responsive to said setting means and said detecting means for generating a pulse signal, the duty cycle of the pulse signal being controlled by the setting of said setting means, and said generating means comprising determining means for controlling the frequency of the pulse signal in response to a result of the detection by said detecting means such that the frequency changes as the temperature of the switching transistor(s) changes to maintain the power consumption and related temperature of said transistor(s) at a safe level;
- and
- control means responsive to said position sensor and the pulse signal for controlling said switching circuit means to supply the exciting current necessary for rotating the motor to the coils in a pulse pattern according to the pulse signal generated by said generating means.
Dependencies are inferred from the claim text.