This power conversion device converts AC power to DC power and is provided with: a rectifier unit including a thyristor; a capacitor provided at a stage subsequent to the rectifier unit; and a control unit for controlling the firing of the thyristor. The control unit fires the thyristor after a predetermined time from when a zero-cross point where the voltage of the AC power is zero has been reached, thereby supplying power to the capacitor, said predetermined time being determined in accordance with a predetermined frequency of the AC power. The control unit also sets the predetermined time short every time when firing the thyristor and, when the frequency of the AC power has deviated from the predetermined frequency, performs control so as not to fire the thyristor after the predetermined time determined in accordance with the predetermined frequency.

This power conversion device converts AC power to DC power and is provided with: a rectifier unit including a thyristor; a capacitor provided at a stage subsequent to the rectifier unit; and a control unit for controlling the firing of the thyristor. The control unit fires the thyristor after a predetermined time from when a zero-cross point where the voltage of the AC power is zero has been reached, thereby supplying power to the capacitor, said predetermined time being determined in accordance with a predetermined frequency of the AC power. The control unit also sets the predetermined time short every time when firing the thyristor and, when the frequency of the AC power has deviated from the predetermined frequency, performs control so as not to fire the thyristor after the predetermined time determined in accordance with the predetermined frequency.

An AC input power converter comprising a rectifier circuit (D3, D4, D5, D6) for rectifying an AC input signal, a first unidirectional device (D1) coupled in series with a first capacitor (C1) for charging the first capacitor (C1) and wherein the first unidirectional device (D1) and the first capacitor (C1) are arranged in parallel to an output of the rectifier circuit (D3, D4, D5, D6), a second unidirectional device (D2) coupled in series with a second capacitor (C2) for charging the second capacitor (C2) and wherein the second unidirectional device (D2) and the second capacitor (C2) are arranged in parallel to an output of the rectifier circuit (D3, D4, D5, D6), a first output (OUT1) for providing a first power and a first average voltage to a first power converter, wherein the first output (OUT1) s coupled to a first node between the first capacitor (C1) and the first unidirectional device (D1) and a second output (OUT2) for providing a second power and a second average voltage to a second power converter, wherein the second output (OUT2) is coupled to a second node between the second capacitor (C2) and the second unidirectional device (D2), wherein the first capacitor (C1) has a first value and the second capacitor (C2) has a second value, and wherein the first value of the first capacitor and the second value of the second capacitor are selected such that when the first power is lower than the second power, the first average voltage is larger than the second average voltage, and when the first power is larger than the second power, the first average voltage is lower than the second average voltage.

An AC input power converter comprising a rectifier circuit (D3, D4, D5, D6) for rectifying an AC input signal, a first unidirectional device (D1) coupled in series with a first capacitor (C1) for charging the first capacitor (C1) and wherein the first unidirectional device (D1) and the first capacitor (C1) are arranged in parallel to an output of the rectifier circuit (D3, D4, D5, D6), a second unidirectional device (D2) coupled in series with a second capacitor (C2) for charging the second capacitor (C2) and wherein the second unidirectional device (D2) and the second capacitor (C2) are arranged in parallel to an output of the rectifier circuit (D3, D4, D5, D6), a first output (OUT1) for providing a first power and a first average voltage to a first power converter, wherein the first output (OUT1) s coupled to a first node between the first capacitor (C1) and the first unidirectional device (D1) and a second output (OUT2) for providing a second power and a second average voltage to a second power converter, wherein the second output (OUT2) is coupled to a second node between the second capacitor (C2) and the second unidirectional device (D2), wherein the first capacitor (C1) has a first value and the second capacitor (C2) has a second value, and wherein the first value of the first capacitor and the second value of the second capacitor are selected such that when the first power is lower than the second power, the first average voltage is larger than the second average voltage, and when the first power is larger than the second power, the first average voltage is lower than the second average voltage.

An AC-DC conversion device that includes a major circuit portion and a control circuit. The major circuit portion includes a converter in which multiple switch portions in a bridge connection include separately-excited switching elements and snubber circuits connected in parallel with the switching elements; and the major circuit portion is connected to an alternating current power supply and a direct current circuit and applies, to the direct current circuit, an alternating current voltage applied from the alternating current power supply by an ON of the multiple switch portions. The control circuit controls the voltage applied to the direct current circuit by controlling the ON timing of the multiple switch portions by inputting a control pulse to each of the multiple switch portions.

An AC-DC conversion device that includes a major circuit portion and a control circuit. The major circuit portion includes a converter in which multiple switch portions in a bridge connection include separately-excited switching elements and snubber circuits connected in parallel with the switching elements; and the major circuit portion is connected to an alternating current power supply and a direct current circuit and applies, to the direct current circuit, an alternating current voltage applied from the alternating current power supply by an ON of the multiple switch portions. The control circuit controls the voltage applied to the direct current circuit by controlling the ON timing of the multiple switch portions by inputting a control pulse to each of the multiple switch portions.

A power converter comprising an energy transfer element is coupled between an input of the power converter and an output of the power converter. A cascode circuit generates a first sense signal and a second sense signal. A controller controls the switching of the cascode circuit to transfer energy from the input of the power converter to the output of the power converter. The controller comprising a current sense circuit generates a current limit signal and an overcurrent signal in response to the first sense signal and the second sense signal. A control circuit generates a control signal in response to the current limit signal and the overcurrent signal. A drive circuit comprising a first stage gate drive circuit generates a drive signal in response to the control signal to reduce EMI, and a second stage of gate drive circuit to enable accurate current sensing of the cascode circuit.

A motor drive system includes a converter configured to convert power between AC power in a power source and DC power in a DC link, an inverter for drive configured to convert power between the DC power and AC power in a servomotor for drive, a motor control unit for drive configured to control the servomotor for drive, a power storage device configured to store the DC power from the DC link or supplies the DC power to the DC link, and a determination unit configured to determine whether the holding energy of the power storage device is lower than a threshold for energy shortage determination, wherein when the holding energy is lower than the threshold for energy shortage determination, the motor control unit for drive controls the servomotor for drive by setting an additional standby period in which the servomotor for drive is inactive in a predetermined operation pattern.

An AC-DC converter can include: a rectifying circuit configured to convert an AC input voltage into a DC voltage, where at least one active switching device is included in one conductive rectifying loop of the rectifying circuit; a control circuit configured to control switching states of the active switching devices according to an output voltage of the AC-DC converter and the AC input voltage, in order to decrease an error between the DC voltage and the output voltage of the AC-DC converter; and a DC-DC converter configured to convert the DC voltage into the output voltage of the AC-DC converter.

A power converter comprising an energy transfer element is coupled between an input of the power converter and an output of the power converter. A cascode circuit generates a first sense signal and a second sense signal. A controller controls the switching of the cascode circuit to transfer energy from the input of the power converter to the output of the power converter. The controller comprising a current sense circuit generates a current limit signal and an overcurrent signal in response to the first sense signal and the second sense signal. A control circuit generates a control signal in response to the current limit signal and the overcurrent signal. A drive circuit comprising a first stage gate drive circuit generates a drive signal in response to the control signal to reduce EMI, and a second stage of gate drive circuit to enable accurate current sensing of the cascode circuit.