Fanuc Corporation

Other

Masakazu Niwa

Yasusuke Iwashita

Kenta Yamamoto

Koujirou Sakai

Takahiro Akiyama

Tadashi Okita

Shinichi Horikoshi

Takashi Harada

Junpei Maruyama

Tomohisa Tsutsumi

Geng Li

A motor control apparatus includes a PWM rectifier which converts AC power on a three-phase AC input power supply side into DC power or which converts DC power on a DC output side into AC power, a smoothing capacitor which is connected to a DC link on the DC output side of the PWM rectifier, a DC voltage detection unit which detects a DC voltage of the smoothing capacitor, an LCL filter which is connected to the AC input power supply side of the PWM rectifier, a power disconnection unit which is connected to an AC power supply side of the LCL filter, and a control unit which applies, when power is disconnected by the power disconnection unit, electric current to the LCL filter by controlling the PWM rectifier, and lowers the DC voltage to a desired value by discharging energy stored in the smoothing capacitor.

Motor control apparatus having function of discharging energy remaining in DC link

A power supply converter controller in an injection molding machine continuously operates a power supply converter in a continuous operation interval, operates the power supply converter in a step-up interval to increase a voltage of an electric storage unit up to a step-up voltage, and intermittently operates the power supply converter in an intermittent operation interval.

Control apparatus of injection molding machine

A PWM rectifier includes a main circuit unit carrying out AC-DC power conversion by PWM-control, a PWM control unit PWM-controlling the main circuit unit, a DC voltage detection unit detecting a DC voltage across a smoothing capacitor connected to the DC-side of the main circuit unit, a DC voltage storage unit storing respective DC voltages at the start and end times of an initial boost period during which the smoothing capacitor having been charged to an AC voltage peak value is further charged to a higher voltage, an input power calculation unit calculating input power flowing in from the AC-side based on an AC voltage and current, an integral power calculation unit calculating integral power from the input power over the initial boost period, and a capacitance calculation unit calculating the capacitance of the smoothing capacitor based on the respective DC voltages and the integral power.

PWM rectifier including capacitance calculation unit

A PWM rectifier includes a main circuit unit which performs a power conversion on the basis of a PWM control signal, a DC voltage loop control unit which generates a current command, a current command restriction unit which sets, when an absolute value of the current command exceeds a limit value, the limit value as a final current command, and otherwise sets the current command as the final current command, a DC voltage loop saturation determination unit which determines a saturation state when the final current command is set to the limit value and otherwise determines as a non-saturation state, a DC voltage command calculation unit which changes the DC voltage command into a value obtained by adding an offset to a minimum or maximum value of the DC voltage value, and a PWM control signal generation unit which generates the PWM control signal from the final current command.

PWM rectifier for motor drive connected to electric storage device

A motor control apparatus includes a rectifier for rectifying AC power to output DC power; an inverter for performing power interconversion of DC power of a DC link and AC power being driving power or regenerative power of a motor by being connected to the DC link being a DC output side of the rectifier; and at least two resistance discharge units each for performing resistance discharge of DC power of the DC link, the resistance discharge units each being connected to the DC link, in which each resistance discharge unit starts a resistance discharge operation for performing resistance discharge of DC power of the DC link at a DC voltage value in the DC link exceeding a first threshold value and stops the resistance discharge operation at a DC voltage value in the DC link smaller than a second threshold value below the first threshold value.

Motor control apparatus including at least two resistance discharge units

A motor control device includes a rectifier, an inverter connected to the rectifier via the DC link, a power failure detecting unit detecting power failure, a voltage detecting unit detecting a DC voltage at the DC link, an electric storage unit storing DC power, a charging unit that can make charging by boosting to a voltage higher than the DC voltage, a discharging unit discharging DC power, a resistance discharge device that performs resistance discharging of DC power at the DC link when the DC voltage after power failure is equal to or higher than a predetermined start level and that does not perform resistance discharging when the DC voltage is equal to or lower than a predetermined stop level, and a discharging operation determining unit operating the discharging unit when the DC voltage at the DC link after power failure is equal to or lower than a predetermined threshold.

Motor control device including electric storage device and resistance discharge device

A motor driving device includes a rectifier, an inverter connected to a DC link on a DC side of the rectifier, a power failure detecting unit for detecting a power failure on the alternating side of the rectifier, an electric storage device connected to the DC link, a charging unit that possesses a voltage boosting function of charging the electric storage device by direct current power at the DC link, a discharging unit that causes direct current power stored in the electric storage device to be discharged to the DC link, and a control unit that causes the charging unit to operate when the power failure detecting unit does not detect a power failure, or before start of motor drive, and causes the discharging unit and the inverter to operate when the power failure detecting unit detects a power failure.

Motor driving device including electric storage device

A motor drive PWM rectifier includes a control section which generates the PWM signal in accordance with either a three-phase modulation scheme or a two-phase modulation scheme in which a PWM voltage command for one phase selected from among three phases each constituting the PWM voltage command in the three-phase modulation scheme is set and held at a level equivalent to a maximum value or minimum value of the PWM carrier and in which a PWM voltage command for the other two phases created by also applying an offset, required to achieve the setting, to the other two phases, a detecting section which detects three-phase AC current and outputs a detected current value, and a selecting section which selects the two-phase modulation scheme when the detected current value is larger than a first threshold value but smaller than a second threshold value, and otherwise selects the three-phase modulation scheme.

Motor drive PWM rectifier having modulation scheme selector

A motor drive device () of the present invention includes a converter unit () and an inverter unit (). The converter unit () includes: power supply voltage monitoring unit () for detecting a power failure; DC link voltage detecting means (); capacitor total capacity calculating means () which calculates total capacity of DC link smoothing capacitors () and calculates a DC link low-voltage alarm detection level for an instantaneous power failure; DC link low-voltage alarm detection level setting means () which varies the DC link low-voltage alarm detection level for an instantaneous power failure as necessary; and alarm generating means () which monitors the DC link voltage and generates an alarm to protect the converter unit. In the case where a power failure is detected, the DC link low-voltage alarm detection level is increased in accordance with the total capacity of the DC link smoothing capacitors ().

Motor drive device having function of varying DC link low-voltage alarm detection level

A motor drive apparatus includes a rectifier which converts AC power to DC power and DC power to AC power, an inverter which converts the DC power output by the rectifier to AC power and supplies the AC power to a motor, and which converts regenerative power from the motor to DC power and returns the DC power to the rectifier, a DC voltage detection unit which detects a DC output voltage of the rectifier, an AC voltage detection unit which detects an AC output voltage of the rectifier, a frequency calculation unit which calculates the frequency of the AC voltage; a storage unit which stores as a reference value the DC voltage at the start of the regenerative operation, and a power failure detection unit which determines the presence or absence of a power failure by using the DC voltage, the reference value, and the AC voltage frequency.

Motor drive apparatus having power failure detection unit for determining presence or absence of power failure

When the output of motor reaches or exceeds a predetermined value during acceleration of the motor, the control target value of the DC link voltage which is the voltage of a power storage device is gradually lowered in corresponding relationship to the motor output. When the motor enters a constant speed control mode, the DC link control target value is maintained at a constant level. When the motor enters a deceleration control mode, the DC link control target value is gradually raised in corresponding relationship to the motor output, and regenerative power is recovered by the power storage device and reused in the next control cycle.

Motor driving apparatus

During motor acceleration control period that starts at time T, if power supply output or supply current exceeds a predetermined level at time T, PWM control in a PWM converter is turned off until a deceleration control period of Tto Tends. As a result, DC link voltage (voltage of a power storage device) at the start of the deceleration control at time Tdrops to provide space for storing regenerative power; since the PWM control in the PWM converter is off during the deceleration control period, the regenerative power can be stored into the power storage device and reused in the next control cycle.

A motor driving device that accurately achieves power failure detection according to a power failure tolerance with a relatively simple configuration. A counter input computing unit determines, as a counter input value, a value that is inversely proportional to the power failure tolerance determined from a voltage amplitude value and supplies the counter input value to a counter. The counter accumulates the input value at predetermined intervals and outputs an output value. A comparator determines that power failure occurs if the output of the counterexceeds a threshold value.

Motor driving device having power failure detection function

Disclosed is a PWM rectifier in which switching losses in a semiconductor device are reduced without degrading the response of a control system. In a PWM overmodulation region, the modulation scheme is set to a three-phase modulation scheme. In other regions, a switchover condition such as the amplitude of an input current is acquired and compared with a switchover level. If the switchover condition equals or exceeds the switchover level, the modulation scheme is switched over to a modified two-phase modulation scheme which reduces the number of switching operations to two thirds for the same PWM frequency.

PWM rectifier

An excitation current processor of a current controller processes the excitation current corresponding to the magnetic flux instruction from the magnetic flux instruction processor. It multiplies this excitation current with a boost coefficient to obtain an excitation current instruction. Here, the boost coefficient is determined based on the difference obtained by subtracting the magnetic flux estimation value processed by the magnetic flux processor based on the excitation current feedback from the voltage conversion device from the magnetic flux instruction input from the magnetic flux instruction processor. Further, the boost coefficient can be found from the function of time from the start of the rise of the magnetic flux.

Growing community of inventors

Yamanashi, Japan

Masakazu Niwa