Electricity: motive power systems – Synchronous motor systems – Field winding circuits
Reexamination Certificate
1999-02-19
2001-03-27
Masih, Karen (Department: 2837)
Electricity: motive power systems
Synchronous motor systems
Field winding circuits
C318S700000, C318S717000, C318S432000, C318S430000, C318S433000, C318S434000
Reexamination Certificate
active
06208109
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a synchronous motor driving method, compressor driving method, device for the methods, and brushless DC motor driving device. More particularly, the present invention relates to a synchronous motor driving method for driving a synchronous motor such as a brushless DC motor or the like using an inverter and a device for the method, and a compressor driving method for driving a compressor using the synchronous motor which is driven by such method or device and a device for the method, and a brushless DC motor driving device for driving a brushless DC motor using an inverter.
BACKGROUND ART
In the past, a torque controlling technique (refer to the Patent Publication Gazett Tokukaihei 6-42789) is known which controls an input voltage or an input current of an inverter motor so that vibration following the change in rotation speed within one rotation of a compressor having one cylinder is decreased.
Further, a brushless DC motor is devotedly employed as a driving source which is easier in torque controlling than an AC motor due to a position detection mechanism which is previously provided to the brushless DC motor.
Among brushless DC motors, when a surface magnet arrangement brushless DC motor, in which a rotor has permanent magnets which are provided at a surface of the rotor, is employed and torque is controlled, a method for controlling a d-axis current to be 0 which gives no influence to motor torque generation, that is the method for controlling a phase of current to be the same phase as a phase of a generation voltage due to a motor speed (the phase of current equals to 0), is known as a driving method which is free from lowering in efficiency, and is widely employed because of simplification in control.
On the other hand, an embedded magnet arrangement brushless DC motor, in which a rotor has permanent magnets which are embedded in an interior of the rotor, can simultaneously output two generation torques, that is a magnetic torque and a reluctance torque. Therefore, the embedded magnet arrangement brushless DC motor has a characteristic effect such that driving with higher efficiency than the surface magnet arrangement brushless DC motor is realized by determining distribution of the two torques to be adequate in response to a load torque so that the current is determined to have a minimum value and the total torque is determined to have a maximum value (hereinafter, referred to as “maximum torque control”). The embedded magnet arrangement brushless DC motor has developed in application to an air-conditioner or the like in recent years which is required energy saving especially.
Further, a maximum torque control method for controlling an embedded magnet arrangement brushless DC motor is recited in “a controlling method which is adequate to an embedded magnetic arrangement PM motor (Umekomi-jishaku-kouzou-PM-mota ni tekishita seigyphou)”, Motimoyo et al., Denki-gakkai Handoutai Denryoku Kenkyuukai Shiryou SPC-92 5. It is known that the maximum torque control is -realized by controlling d-, and q-axis currents based upon a relational equation which is determined based upon electrical constants of a motor.
But, when the maximum torque control and the torque control are combined with one another, the following disadvantages arise.
(1) Modeling errors due to a motor temperature and magnetic saturation-are generated so that a maximum torque condition is not satisfied constantly. And, for solving problems (specifically, changes in winding resistance and the speed electromotive force constant following an increase in temperature, and changes in d-, and q-axis inductance values and the speed electromotive force constant due to magnetic saturations due to modeling errors of a motor, changes in various parameters due to temperature and magnetic saturation should be actually measured and are considered in operations. This is extremely difficult in actual application.
(2) When the maximum torque control is combined with torque control which cancels harmonic components up to higher harmonics which gives little influence in vibration, electric power is consumed beyond the necessary amount so that driving with high efficiency is not realized.
(3) A peak current is increased by the torque control so that the peak current is over the limit value of an inverter current. Therefore, an operation point should be shifted from an operation point of the maximum torque control so that efficiency is decreased accordingly.
DISCLOSURE OF THE INVENTION
The present invention was made in view of the above problems.
It is an object of the present invention to offer a synchronous motor driving method, compressor driving method, and device for the methods, for realizing torque control which drives a cyclic intermittent load in a maximum efficiency condition, has a practical arrangement, and decreases low speed vibration.
It is another object of the present invention to offer a brushless DC motor driving device for enlarging a driving range and for improving efficiency.
A synchronous motor driving method of a first embodiment according to the present invention is a method for superposing a varying amount upon an amplitude and a phase of a current waveform or voltage waveform when torque control is performed for suppressing speed change within one rotation by a synchronous motor controlled with an inverter which motor drives a load having a cyclic torque change.
A synchronous motor driving method of a second embodiment according to the present invention is a method for controlling a varying amount in phase based upon varying amount in amplitude which is controlled based upon an output of a torque control section.
A synchronous motor driving method of a third embodiment according to the present invention is a method for controlling a varying amount in amplitude based upon a varying amount in phase which is controlled based upon an output of a torque control section.
A synchronous motor driving method of a fourth embodiment according to the present invention is a method for controlling a varying amount in amplitude based upon an output of a torque control section, and for controlling a varying amount in phase based upon a detection amount which is related to efficiency.
A synchronous motor driving method of a fifth embodiment according to the present invention is a method for controlling a varying amount in phase based upon an output of a torque control section, and for controlling a varying amount in amplitude based upon a detection amount which is related to efficiency.
A synchronous motor driving method of a sixth embodiment according to the present invention is a method which employs an amount corresponding to a fundamental wave and lower harmonics as the varying amount.
A synchronous motor driving method of a seventh embodiment according to the present invention is a method which employs an amount corresponding to a fundamental wave as the varying amount.
A synchronous motor driving method of an eighth embodiment according to the present invention is a method for superposing a third harmonic upon the varying amount in amplitude.
A synchronous motor driving method of a ninth embodiment according to the present invention further includes a method for detecting a magnetic pole position of a rotor of the synchronous motor by integrating a difference between a first center point voltage and a second center point voltage, the first center point voltage being obtained by resistances, each having one end which is connected to an output terminal of each phase of the inverter and another end which is connected to one another, and the second center point voltage being obtained by connecting one end of a stator winding of each phase of the synchronous motor to one another.
A compressor driving method of a tenth embodiment according to the present invention is a method for driving a one cylinder compressor using a synchronous motor which is driven by the synchronous motor driving method of one of the first to ninth embodiments.
A synchronous motor driving device of an e
Kitano Nobuki
Kosaka Manabu
Sanga Yoshihito
Yamai Hiroyuki
Masih Karen
Smith , Gambrell & Russell, LLP
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