Abstract: There is provided a gate drive circuit that controls a gate voltage applied to a gate terminal of a switching element and drives the switching element. The gate drive circuit includes an overcurrent detection circuit that detects an overcurrent state based on a value of a current flowing through the switching element. A monitor voltage of a power supply line that is connected to the switching element and supplies power to the switching element is input to the overcurrent detection circuit, and the overcurrent detection circuit detects an overvoltage state when the monitor voltage is equal to or greater than a predetermined threshold value.

Abstract: A semiconductor element drive device is provided to solve a problem that because a case of a change in the temperature of the semiconductor element or a current flowing through the semiconductor element is not take into consideration, switching loss and noise cannot be reduced sufficiently. In accordance with input sensing information (temperature T, current I), a timing control unit 3 outputs a delay signal Q to control timing of driving a current increasing circuit 5 so that a reduction of switching loss of an IGBT 101 is maximized. When the IGBT 101 is in turn-on mode or turn-off mode, the current increasing circuit 5 outputs a drive signal in response to the delay signal Q delayed by a given time from output of the drive instruction signal P. In this way, the current increasing circuit 5 increases the current that causes the gate capacitor of the IGBT 101 to be charged/discharged in response to the delay signal Q, thereby increasing a switching speed to reduce switching loss.

Abstract: Even when a large current is intentionally flowed during a high-temperature conduction of a semiconductor element, there is a problem in that an overcurrent state is detected to stop current. In the present invention, an overcurrent detector 4 detects overcurrent when an input voltage Vin reaches a threshold voltage Vth, and outputs an overcurrent detection signal c to a gate driving unit 3. On the other hand, when a temperature detection signal a and a current control signal b are input, a transistor 52 is conducted, and the input voltage Vin of the overcurrent detector 4 becomes zero. In this case, the input voltage Vin of the overcurrent detector 4 does not reach the threshold voltage Vth. Therefore, the output of the drive signal output from the gate driving unit 3 is not stopped. For this reason, a large current can flow in a drain current Ids.

Abstract: A semiconductor element drive device is provided to solve a problem that because a case of a change in the temperature of the semiconductor element or a current flowing through the semiconductor element is not take into consideration, switching loss and noise cannot be reduced sufficiently. In accordance with input sensing information (temperature T, current I), a timing control unit 3 outputs a delay signal Q to control timing of driving a current increasing circuit 5 so that a reduction of switching loss of an IGBT 101 is maximized. When the IGBT 101 is in turn-on mode or turn-off mode, the current increasing circuit 5 outputs a drive signal in response to the delay signal Q delayed by a given time from output of the drive instruction signal P. In this way, the current increasing circuit 5 increases the current that causes the gate capacitor of the IGBT 101 to be charged/discharged in response to the delay signal Q, thereby increasing a switching speed to reduce switching loss.

Abstract: Even when a large current is intentionally flowed during a high-temperature conduction of a semiconductor element, there is a problem in that an overcurrent state is detected to stop current. In the present invention, an overcurrent detector 4 detects overcurrent when an input voltage Vin reaches a threshold voltage Vth, and outputs an overcurrent detection signal c to a gate driving unit 3. On the other hand, when a temperature detection signal a and a current control signal b are input, a transistor 52 is conducted, and the input voltage Vin of the overcurrent detector 4 becomes zero. In this case, the input voltage Vin of the overcurrent detector 4 does not reach the threshold voltage Vth. Therefore, the output of the drive signal output from the gate driving unit 3 is not stopped. For this reason, a large current can flow in a drain current Ids.

Abstract: Circuit configurations become complicate as a power circuit is expanded, and switching elements are necessarily controlled using invert circuits even when an inverter operates normally. A drive circuit 911 monitors soundness of a gate power circuit 10. When a voltage value P3 is less than a predetermined threshold, the drive circuit determines that a failure occurs in the gate power circuit 10, and outputs a signal P4 to a controller 6. After receiving the signal P4, the controller 6 outputs a signal to a signal line S1 to operate a photovoltaic coupler of a power supply circuit 92. Then, the MOS transistor T1 in the battery circuit 93 enters a conduction state. The charges accumulated in the capacitor C1 are immediately accumulated to the gate electrode of the switching element 81 to turn on the switching element 81. In addition, the charges discharged from the capacitor C1 are charged from the photovoltaic coupler.

Abstract: Circuit configurations become complicate as a power circuit is expanded, and switching elements are necessarily controlled using invert circuits even when an inverter operates normally. A drive circuit 911 monitors soundness of a gate power circuit 10. When a voltage value P3 is less than a predetermined threshold, the drive circuit determines that a failure occurs in the gate power circuit 10, and outputs a signal P4 to a controller 6. After receiving the signal P4, the controller 6 outputs a signal to a signal line S1 to operate a photovoltaic coupler of a power supply circuit 92. Then, the MOS transistor T1 in the battery circuit 93 enters a conduction state. The charges accumulated in the capacitor C1 are immediately accumulated to the gate electrode of the switching element 81 to turn on the switching element 81. In addition, the charges discharged from the capacitor C1 are charged from the photovoltaic coupler.

Abstract: The present invention is devised to allow accurate determination on quality of a current sensor, and provide a current sensor reduced in size and cost and an inverter having the current sensor. A direct-current sensor 380 detects direct currents supplied to a plurality of inverters 300 and 301 for driving an alternating-current motor 200 in which winding wires of a stator are independent from each other in individual phases and a voltage is individually applied to the independent winding wires. The plurality of inverters has a P connecting wire 150 connecting P buses and an N connecting wire 160 connecting N buses. The direct-current sensor 380 has a core surrounding the P connecting wire and the N connecting wire to detect the currents flowing into and out of the P bus and the N bus. This makes it possible to employ a small-capacity current sensor, improve the sensor accuracy, and allow accurate determination on the quality of the current sensor.

Abstract: An object of the present invention is to diagnose a state of a voltage divider while performing a normal measurement to improve reliability. A voltage detection apparatus according to the present invention includes: a first resistor for dividing voltage of a detection unit into a first divided voltage value; and a test pattern insertion circuit unit including a second resistor for dividing the first divided voltage value into a second divided voltage value and a switching device, wherein the test pattern insertion circuit unit is connected to an equipotential connection point to the first divided voltage value, and wherein a state of the first resistor is detected based on the second divided voltage value when the switching device is conductive.

Abstract: An object of the present invention is to diagnose a state of a voltage divider while performing a normal measurement to improve reliability. A voltage detection apparatus according to the present invention includes: a first resistor for dividing voltage of a detection unit into a first divided voltage value; and a test pattern insertion circuit unit including a second resistor for dividing the first divided voltage value into a second divided voltage value and a switching device, wherein the test pattern insertion circuit unit is connected to an equipotential connection point to the first divided voltage value, and wherein a state of the first resistor is detected based on the second divided voltage value when the switching device is conductive.

Abstract: An inverter drive device includes a drive circuit that outputs a gate voltage signal of a power semiconductor element; and a Zener clamping protection circuit that acquires an emitter electrode side voltage of the power semiconductor element, and, if that voltage is greater than a predetermined voltage value, performs clamping of the gate voltage of the drive circuit after a predetermined time interval has elapsed from the acquisition of the emitter electrode side voltage. The Zener clamping protection circuit includes a latch circuit that, after the emitter electrode side voltage has been acquired, continues the clamping of the gate voltage by the Zener clamping protection circuit during an interval.

Abstract: An electric power converter is provided with a plurality of power-conversion elements; a first control circuit that outputs a first control signal; an electricity storage circuit; a second control circuit that outputs a second control signal when the direct-current power source that supplies electrical power to the first control circuit is not normal; and a drive circuit that outputs drive signals for driving the plurality of power-conversion elements. Each of the power-conversion elements is either a power-conversion element of the upper arm connected to the high-voltage side or a conversion element of the lower arm connected to the low-voltage side. In cases when the voltage of the electricity storage circuit is at a higher predetermined first voltage value, the second control circuit outputs a second control signal so that all the power-conversion elements of the upper arm or the lower arm are turned on and the others are turned off.

Abstract: An inverter device includes an inverter circuit, a control circuit, a first drive circuit, a second drive circuit, first and second photocouplers, and a signal switching part. The signal switching part directly transmits the first and second signals outputted from the first photocoupler and the second photocoupler to the corresponding first and second drive circuits respectively when at least one of the first and second signals is an OFF command.

Abstract: A power conversion system according to the present invention includes: an inverter circuit unit that converts a direct current power supplied from a direct current source into an alternating current power, the direct current power being supplied to the inverter circuit through a contactor that conducts and interrupts the direct current; a capacitor that smoothes the direct current power; a discharge circuit unit that is connected to the capacitor in parallel, and that includes a discharge resistor for discharging a charge stored in the capacitor and a switching element for the discharge resistor, being connected in series to the discharge resistor; a voltage detection circuit unit that detects voltage between both terminals of the capacitor; a first discharge control circuit that includes a first microcomputer, and that outputs a control signal to control switching of the switching element for discharging; and a second discharge control circuit that outputs an interruption signal to interrupt the switching el

Abstract: An inverter drive device includes a drive circuit that outputs a gate voltage signal of a power semiconductor element; and a Zener clamping protection circuit that acquires an emitter electrode side voltage of the power semiconductor element, and, if that voltage is greater than a predetermined voltage value, performs clamping of the gate voltage of the drive circuit after a predetermined time interval has elapsed from the acquisition of the emitter electrode side voltage. The Zener clamping protection circuit includes a latch circuit that, after the emitter electrode side voltage has been acquired, continues the clamping of the gate voltage by the Zener clamping protection circuit during an interval.

Abstract: An electric power converter is provided with a plurality of power-conversion elements; a first control circuit that outputs a first control signal; an electricity storage circuit; a second control circuit that outputs a second control signal when the direct-current power source that supplies electrical power to the first control circuit is not normal; and a drive circuit that outputs drive signals for driving the plurality of power-conversion elements. Each of the power-conversion elements is either a power-conversion element of the upper arm connected to the high-voltage side or a conversion element of the lower arm connected to the low-voltage side. In cases when the voltage of the electricity storage circuit is at a higher predetermined first voltage value, the second control circuit outputs a second control signal so that all the power-conversion elements of the upper arm or the lower arm are turned on and the others are turned off.

Abstract: According to the present invention, an electrical power conversion system includes: a motor; an inverter circuit that outputs three-phase (U-phase, V-phase, W-phase) alternating currents to the motor; a current sensor that detects each of the three-phase alternating currents; and a control circuit that controls the inverter circuit based on a torque command value and values detected by the current sensor, so that the three-phase alternating currents outputted from the inverter circuit are formed as sine waves; and wherein the control circuit includes: a current component extraction unit that, based on the values detected by the current sensor, for each phase, extracts current components superimposed upon each of three-phase alternating currents; and an AC current abnormality detection unit that detects abnormality of an AC current flowing to the motor, based on the phases of the current components for any two phases among the three-phase alternating currents.

Abstract: The present invention provides a power converter including a power semiconductor device, a driver circuit section that outputs a driving signal for driving the power semiconductor device, a buffer circuit section that includes a PNP transistor and an NPN transistor and that outputs a gate voltage for driving the power semiconductor device, a first delay circuit section that receives the driving signal and that generates a first delay signal on the basis of the received driving signal, a first MOSFET that has a drain electrode connected with the output of the buffer circuit section and that is driven on the basis of the first delay signal.

Abstract: An inverter device includes: an inverter circuit which includes an upper-arm-use first switching element (328U to 328W) and a lower-arm-use second switching element (330U to 330W); a control circuit (319) which outputs a first signal which is an ON/OFF command for the first switching element and a second signal which is an ON/OFF command for the second switching element respectively; a first drive circuit (610U to 610W) which performs ON/OFF driving of the first semiconductor switching element based on the ON/OFF command which is the first signal; a second drive circuit (611U to 611W) which performs ON/OFF driving of the second semiconductor switching element based on the ON/OFF command which is the second signal; and a signal switching part (616U to 616W) which directly inputs the first and second signals outputted from the control circuit to the corresponding first and second drive circuits respectively when at least one of the first and second signals is an OFF command, and interrupts inputting of the firs

Abstract: A power conversion device (140) includes an inverter circuit (12) that includes a bridge-connected power semiconductor element and is connected to a DC power supply through an openable and closable contactor (15), a driver circuit (21) to drive the power semiconductor element, a driver circuit control part (18) that performs PWM (Pulse Width Modulation) control on the driver circuit and causes the power semiconductor element to perform a switching operation, a voltage smoothing capacitor (500) connected in parallel to an input side of the inverter circuit, a driver power supply circuit (27) that is connected in parallel to the voltage smoothing capacitor, is inputted with a voltage applied to the voltage smoothing capacitor and supplies electric power to the driver circuit, a discharge circuit that includes a resistor (25) for discharging an electric charge of the voltage smoothing capacitor and a discharging switching element (26) connected in series to the resistor, and is connected in parallel to the volta