Patent application number | Description | Published |
20090028720 | Vacuum pump - A vacuum pump capable of accurately detecting a rotor temperature based on a change in permeability of a magnetic material. Two targets are fixed to a nut opposed to a gap sensor. The nut is made of pure iron, and a surface of the nut opposed to the gap sensor serves as a target. The target has a Curie temperature greater than a temperature monitoring range, and each of the targets has a Curie temperature falling within the temperature monitoring range. When the targets become opposed to the gap sensor in turn according to rotation of a rotor, three types of signals are output from the gap sensor. The difference-signal generation means generates a difference signal of each the targets, on the basis of a signal of the target. The difference signal is compared with a reference signal V | 01-29-2009 |
20100303644 | VACUUM PUMP - A condensation sensor is provided within a power supply device that is provided integratedly with a vacuum pump main unit. When the condensation sensor detects condensation within the power supply device, a CPU closes a cooling water valve. This stops the flow of cooling water that flows through the interior of the power supply device, through a cooling water duct. | 12-02-2010 |
20130147296 | MAGNETIC LEVITATION TYPE VACUUM PUMP AND MAGNETIC LEVITATION DEVICE - A magnetic levitation type vacuum pump includes an electromagnet magnetically levitating a rotor by a magnetic force, an electromagnet driving circuit supplying an electromagnet current including a magnetic levitation control current component and a carrier wave current component having a frequency band higher than the magnetic levitation control current component to the electromagnet coil, a levitated position detecting circuit detecting the carrier wave current component and generating a levitated position signal of the rotor, a magnetic levitation control circuit inputting a current command of the magnetic levitation control current component to the electromagnet driving circuit based on the levitated position signal. The electromagnet coil has a primary coil and a secondary coil connected in parallel with the primary coil. An interrupting circuit connected in series with the secondary coil for the carrier wave current component passing therethrough and interrupting the magnetic levitation control current component is further included. | 06-13-2013 |
20140112801 | MOTOR DRIVING DEVICE AND VACUUM PUMP - A motor driving device comprises: an inverter having a plurality of switching elements for driving a motor; an arithmetic section for calculating a rotational speed and a magnetic pole electric angle of a motor rotor based on information about a motor phase voltage and information about a motor phase current; a delay correcting section for correcting a phase delay of the magnetic pole electric angle calculated by the arithmetic section so as to generate corrected magnetic pole electric angle; a driving command generating section for generating a sinusoidal wave driving command based on a difference between the rotational speed and a target rotational speed and the corrected magnetic pole electric angle; and a PWM signal generating section for generating a PWM control signal for controlling on/off of the plurality of switching elements based on the sinusoidal wave driving command. | 04-24-2014 |
20140203742 | MOTOR DRIVING DEVICE AND VACUUM PUMP - A motor driving device comprises an inverter, a first arithmetic section, a driving command generating section and a PWM signal generating section. The first arithmetic section calculates a rotational speed and a magnetic pole electrical angle of a motor rotor based on information about a motor phase voltage and information about a motor phase current. The first arithmetic section includes a counter electromotive voltage arithmetic section, a converting section, a second arithmetic section, a third arithmetic section, and a fourth arithmetic section. The first arithmetic section outputs a sum of the magnetic pole phase error and the integrated value as the magnetic pole electrical angle. | 07-24-2014 |
20140210385 | MOTOR DRIVING DEVICE AND VACUUM PUMP - A motor driving device comprises a first arithmetic section calculating a rotational speed and a magnetic pole electrical angle of a motor rotor, a current command setting section setting a d-axis current command and a q-axis current command in a rotating coordinate dq system based on a difference between the rotational speed and a target rotational speed, a driving command generating section generating a sinusoidal wave driving command based on the d-axis current command, the q-axis current command, the rotational speed and the magnetic pole electrical angle and a PWM signal generating section. When the rotational speed has a positive value indicating a positive rotational state, the current command setting section sets the q-axis current command of acceleration driving, and when the rotational speed has a negative value indicating a reverse rotational state, the current command setting section sets the q-axis current command of deceleration driving. | 07-31-2014 |
20140212312 | MAGNETIC BEARING DEVICE AND VACUUM PUMP - A magnetic bearing device comprises a controller configured to obtain magnetic levitation information of the rotor shaft by AD sampling of current detection signals from the plurality of current sensors and a sum signal obtained by adding the pair of current detection signals relating to the pair of electromagnets, and perform PWM control of the excitation amplifiers based on the magnetic levitation information. The controller performs PWM control so that a length of one of an on-duty period and an off-duty period of the PWM carrier signal is always longer than a predetermined time period based on an attenuation characteristic of a spike noise produced in the electromagnetic current, and performs the AD sampling after the predetermined time period passes from starting timing of one of the on-duty period and the off-duty period. | 07-31-2014 |
20140219841 | MAGNETIC BEARING DEVICE AND VACUUM PUMP - A predetermined timing is a timing at which the sampling timing is in a vicinity of a maximum peak position of the carrier wave signal and a timing at which the sampling timing is in a vicinity of a minimum peak position. The demodulation arithmetic section outputs, as the demodulation calculated result, a value d3 calculated with d3=(d1−d2)/2 when a data value of the digital signal sampled in the vicinity of the maximum peak position is denoted by d1 and a data value of the digital signal sampled in the vicinity of the minimum peak position is denoted by d2. | 08-07-2014 |
20140271237 | VACUUM PUMP - An estimating section detects a signal including counter electromotive voltage information of the motor, and estimating a magnetic pole electric angle and a rotational speed of the motor. A driving current controller repeats generation and cut-off of the driving current supplied from a power supply to the motor via the inverter circuit or regenerated from the motor to the power supply in a low-speed period between a stopped state and a predetermined rotational speed in an accelerating operation at a motor starting time or a decelerating operation at a motor stopping time. The estimating section detects the signal at the cut-off time so as to estimate the magnetic pole electric angle and the rotational speed in the low-speed period. | 09-18-2014 |
20150050170 | MAGNETIC BEARING DEVICE AND VACUUM PUMP - A magnetic bearing device comprises a first carrier generation section generating a first carrier signal; a second carrier generation section generating a second carrier signal whose phase differs by (π/2+θ) radian from the phase of the first carrier signal; a first demodulation section performing demodulation by sampling the first modulated signal at sampling timing shifted by a phase θ from timing at which the first carrier signal becomes a peak; a second demodulation section performing demodulation by sampling the second modulated signal at sampling timing shifted by a phase (−θ) from timing at which the second carrier signal becomes a peak; and a controller controlling current in each of the first radial electromagnet and the second radial electromagnet, based on a result of the demodulation by each of the first demodulation section and the second demodulation section. | 02-19-2015 |