摘要:
An inverter that supplies a desired primary voltage (v1) to an induction motor, a current detector that detects a primary current (i1) from the inverter to the induction motor, a voltage designation value calculating unit that generates a voltage designation value (v1*) for generating the voltage v1, an idling-time speed estimating unit that calculates an estimate value (ωr#) of the rotation speed when the induction motor is idling, and a sequence circuit that commands the operations of these units are provided. The idling-time speed estimating unit switches a method for deriving the estimate value on the basis of a current value in the case where a short circuit is generated between windings when the induction motor is idling.
摘要:
The present invention provides a variable-speed controlling device for use with an induction motor, which includes a means for compensating for the discrepancy between a secondary magnetic flux instruction value and a secondary magnetic flux actually occurring in an induction motor, realizes a satisfactory control by generating the secondary magnetic flux according to the instruction value, and can generate desired torque and improve a motor efficiency. The variable-speed controlling device according to the present invention, for use with an induction motor, includes a voltage instruction value calculating unit, an integrating unit, a power converting circuit, a current detecting unit, an induced voltage calculating unit, a position discrepancy amount calculating unit, and a compensating unit.
摘要:
A variable-speed control apparatus computes the leakage inductance of an AC motor, correctly compensates the leakage inductance, and controls the variable speed of the AC motor. The variable-speed control apparatus has an AC signal generation circuit for generating an AC signal, and obtains a leakage inductance calculation value of the AC motor based on the AC signal and the measured actual current value. The differential value of the summation of a current command value and the AC signal is multiplied by the leakage inductance calculation value to generate a signal for use in compensating the voltage drop caused by the leakage inductance, and added to a voltage command value to cancel the deviation between the actual current value and the M-axis current command value and to obtain the second voltage command value. The second voltage command value is converted into a 3-phase voltage command value and used in controlling the AC motor, and the voltage drop caused by the leakage inductance can be compensated.
摘要:
A polishing pad is used when a surface of a glass workpiece is polished for manufacturing a glass substrate of information recording medium. The polishing pad has a nap layer. The nap layer includes an inner layer that contains a plurality of closed cells, and an outer layer. A plurality of pores are formed on the surface of the outer layer. The sizes of the pores are minute compared to those of the closed cells.
摘要:
An inverter that supplies a desired primary voltage (v1) to an induction motor, a current detector that detects a primary current (i1) from the inverter to the induction motor, a voltage designation value calculating unit that generates a voltage designation value (v1*) for generating the voltage v1, an idling-time speed estimating unit that calculates an estimate value (ωr#) of the rotation speed when the induction motor is idling, and a sequence circuit that commands the operations of these units are provided. The idling-time speed estimating unit switches a method for deriving the estimate value on the basis of a current value in the case where a short circuit is generated between windings when the induction motor is idling.
摘要:
A polishing pad used for precise polishing of the surface of a lapped glass workpiece when a glass substrate for use in data recording media is manufactured from a glass workpiece. The polishing pad comprises a base and a polishing portion laminated on the base and contacting the surface of the glass workpiece at the time of polishing. The polishing portion is formed of a foam made of a synthetic resin having a 100% modulus of 11.8 MPa or less. A type of parameter representing the surface roughness of the polishing portion, namely, the maximum height (Rmax), is 70 μm or less.
摘要:
Biaxially oriented polyester films including polyester polymer, a carbodiimide hydrolysis stabilizer, and a UV absorber are described. The polyester films have a carboxyl end group concentration of 5-20 equivalents per ton, and a haze value of 2% or less. The films exhibit superior transparency and possess stable light transmission characteristics. Methods of making the films and articles produced from the films are also described.
摘要:
Biaxially oriented polyester films including polyester polymer, a carbodiimide hydrolysis stabilizer, and a UV absorber are described. The polyester films have a carboxyl end group concentration of 5-20 equivalents per ton, and a haze value of 2% or less. The films exhibit superior transparency and possess stable light transmission characteristics. Methods of making the films and articles produced from the films are also described.
摘要:
In a speed control device including a speed instruction generating unit, an addition computing unit, a speed control unit, a current controlling unit, an inertia estimating unit, an inertia setting unit, a switching unit and a constant setting unit, when it is possible to perform accelerating or decelerating operation of the electric motor to estimate the inertia moments of the electric motor and a driving target thereof, an operation is carried out to derive an inertia moment estimation value. The proportional gain of the speed control unit is set through the switching unit and the constant setting unit on the basis of the inertia moment estimation value. When it is impossible to perform the above operation, the proportional gain of the speed control unit is set through the switching unit and the constant setting unit on the basis of the inertia moment manual set value.
摘要:
Disclosed are methods and apparatus for quickly measuring a primary resistance value of an AC motor without using high precision detectors and detecting malfunctions such as breaking of wire in the AC motor or in a power converting mechanism, open phase, and three-phase unbalance. A voltage drop attributable to the primary resistance of the AC motor can be estimated by using an estimated resistance value R.sub.1.sup.#, which is estimated in turn by an integral or proportional-plus-integral operation on the deviation between a detected magnetizing current value I.sub.M and a reference magnetizing current value I.sub.M *, in place of an actual primary resistance value R.sub.1. The time for the estimated resistance value R.sub.1.sup.# to reach the true primary resistance value is reduced with a varying reference magnetizing current value I.sub.M **. Variations of the estimated primary resistance values R.sub.1.sup.# s between the phases are corrected with a mean estimated primary resistance value R.sub.1M.sup.# according to a reference phase value .phi.*. Malfunctions such as open phase and breaking of wire are detected by comparing estimated primary resistance values obtained according to the reference phase value .phi.*.