Electricity: motive power systems – Synchronous motor systems – Armature winding circuits
Patent
1987-04-24
1988-08-02
Smith, Jr., David
Electricity: motive power systems
Synchronous motor systems
Armature winding circuits
318740, H02P 320
Patent
active
047615990
DESCRIPTION:
BRIEF SUMMARY
FIELD OF TECHNOLOGY
The present invention relates to a motor controller for use in an AC servo-motor of a synchronous motor type or the like.
More particularly, the present invention relates to an improved motor controller which is arranged to effect a forward/reverse rotation control so as to rotate the motor at a speed corresponding to a speed instruction by applying to the synchronous motor, a reverse rotation torque corresponding to a magnitude of a signal if the speed adjusting instruction is of an adjusting signal larger than a predetermined level, while applying to said synchronous motor, a forward rotation torque corresponding to a magnitude of a signal, if the speed adjusting instruction is of a signal other than the above adjusting signal.
BACKGROUND ART
Although various kinds of control systems are available for the AC servo-motor of a synchronous motor type depending on end uses, a control system based on a square wave current is advantageous from the viewpoint of cost, in a field where comparatively less accuracy is required.
FIG. 5 shows one example of the AC servo-motor referred to above.
In FIG. 5, there are included a synchronous motor 1 provided with a permanent magnet rotor and three-phase drive windings, a rotor position sensor 2 connected to the synchronous motor 1 for detecting the rotor position, a rotary encoder 3 for detecting the rotating direction and speed of the synchronous motor 1, and a power inverter circuit 4 including power transistors Tr1 to Tr6 for switching current to be fed to the respective drive windings of the synchronous motor 1 and diodes D1 to D6 connected in parallel to the respective transistors Tr1 to Tr6. There are also provided a DC power source 5, and a control section 6 for controlling the energization of the transistors Tr1 to Tr6 of the power inverter circuit 4, constituted by blocks as described hereinbelow.
Specifically, there are provided a distributing section 61 which receives signals from the rotor position sensor 2, a PWM circuit 62 and a forward/reverse decision circuit 63, and which outputs a signal indicating which of the transistors of said power inverter circuit 4 should be turned on. The PWM circuit 62 produces pulse width-modulated (referred to as PWM hereinafter) signals corresponding to a speed adjusting signal to be described later, while the forward/reverse decision circuit 63 outputs signals indicating in which direction of the forward and reverse directions, the torque of the synchronous motor 1 should be produced by the speed adjusting instruction to be described later. There are also provided a base drive circuit 64 for controlling the base current of transistors Tr1, Tr2 and Tr3 connected to a plus side of the DC power source 5, and another base drive circuit 65 for similarly controlling the base current of transistors Tr4, Tr5 and Tr6 connected to a minus side of the DC power source 5, a current detecting circuit 7 for detecting the current flowing through the drive windings of the synchronous motor 1, and a speed amplifier 8 for amplifying the difference between the speed instruction and the output signal of the rotary encoder 3. It is to be noted here that the output of the speed amplifier 8 is compared with the output of the current detecting circuit 7, and is applied to the PWM circuit 62 and the forward/reverse decision circuit 63 as the speed adjusting instruction.
In FIG. 6 showing the functions of the distributing section 61, (a), (b) and (c) represent positional signals which differ in their electrical phase angle by 120.degree. and which are outputted from the rotor position sensor 2; (d) denotes an output of the forward/reverse decision circuit, with a "High" level showing the forward rotation and a "Low" level indicating the reverse rotation; (e) represents an output signal of the PWM circuit 62, and (f) to (k) show output signals of the distributing circuit 61 to be applied to the base drive circuits 64 and 65.
Subsequently, functioning of the AC servo-motor having the constructions as described above will be brie
REFERENCES:
patent: 4227138 (1980-10-01), Espelage et al.
Neki Shigeo
Ohara Kenichi
Shibata Nobuho
Yasunobu Isamu
Matsushita Electric - Industrial Co., Ltd.
Smith Jr. David
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