JP5931116B2 - Gate drive circuit - Google Patents

Description

  The present invention relates to a gate driving circuit for driving a power semiconductor element in an inverter for driving a motor for driving a vehicle with an alternating current.

  In a vehicle apparatus including a motor and an inverter that drives the motor, noise and switching loss (power loss) when the power semiconductor element is turned on increase when the motor is subjected to a high load.

  Conventionally, when a power semiconductor element mounted on an inverter is driven by a gate drive circuit in order to reduce switching loss when the motor is heavily loaded, efficiency is emphasized so that the loss of the gate drive circuit is reduced. Control is in progress.

As a conventional technique of a gate drive circuit for changing a switching speed as a driving method of a gate drive circuit for driving a power semiconductor element, a switching speed of a switching state of a switching element constituting an inverter connected to an in-vehicle main machine is set as an inverter. Some change the noise based on the input voltage, the inverter output current, or the temperature of the switching element to balance noise and loss (see, for example, Patent Document 1).

Japanese Patent No. 4844653

  Noise and loss in a vehicle device are in a trade-off relationship, and control of the gate drive circuit that drives the power semiconductor element is only for the conventional efficiency (loss) emphasis. The cost is increased by adding circuits and mechanisms. In the future, regulations regarding noise in vehicle devices are expected to be strengthened, and it is required to optimize the balance between lower noise and higher efficiency.

  Since the inverter described in Patent Document 1 uses a constant voltage type gate drive circuit that is driven by applying a constant voltage to the gate terminal of the power semiconductor element, the noise at the time of turning on the current is large, There was a problem that the loss reduction effect by making the switching speed variable could not be obtained sufficiently.

  The present invention has been made to solve the above-mentioned problems, and its object is to reduce the noise that can reduce the switching loss by high-speed switching while reducing the noise when the power semiconductor element is turned on. To provide a gate driving circuit capable of optimally controlling the balance with high efficiency.

In order to achieve the above object, a gate driving circuit according to the present invention is a voltage-driven power semiconductor element gate driving circuit mounted on an inverter for driving a motor with an alternating current. the current variable portion such noise is reduced in accordance with the current changing unit for changing the charging current, the load state or the driving state of the motor detected by the sensor when the gate of the power semiconductor device is charged control to the a decision circuit Ru changing the switching speed of the semiconductor device for the power, the current variable section, the resistor provided in the path of the charging current, the capacitance value by the judging circuit is controlled When the variable capacitor unit is connected to the resistor and is in the ON state, the charging current is supplied to the power semiconductor element, and the variable capacitor unit is parallel to the resistor. When the first switch element continues, and when the first switch element is in an ON state, the first switch element is turned on by a voltage drop of the resistor, and the resistor and the first switch element are short-circuited, and the first switch element is Ru is composed of a second switch element for controlling to OFF.
In order to achieve the above object, a gate drive circuit according to the present invention is a voltage drive type power semiconductor element gate drive circuit mounted on an inverter for driving a motor with an alternating current. A current variable unit that changes a charging current when the gate of the power semiconductor element is charged with current, and the current variable so that noise is reduced according to the load state or drive state of the motor detected by the sensor And a determination circuit that controls the switching portion of the power semiconductor element to change the switching speed of the power semiconductor element. The variable current section is connected to the variable resistance section and is turned on. A first switching element that applies the charging current to the power semiconductor element when in a state and connects a variable capacitor section in parallel to the variable resistance section; When the switch element is in an ON state, it is turned on by a voltage drop of the variable resistor section, and the first switch element, the variable resistor section, and the variable capacitor section are short-circuited to control the first switch element to OFF. And a second switching element, and the variable resistance unit and the variable capacitor unit are controlled by the determination circuit.

  According to the gate drive circuit of the present invention, it is possible to control the switching speed of the power semiconductor element to the optimum switching speed for the load state and drive state of the power semiconductor element, that is, the load state and drive state of the motor, and to reduce the switching loss of the power semiconductor element. .

It is a block diagram which shows an example of the power conversion system to which the gate drive circuit which concerns on this invention is applied. It is a figure which shows the structure (for 1 arm) of the gate drive circuit by Embodiment 1-3 of this invention. It is a time chart which shows the variable process of the switching speed of the semiconductor element for electric power by Embodiment 1 (motor rotation speed fluctuation | variation) of this invention. It is a time chart which shows the variable process of the switching speed of the semiconductor element for electric power by Embodiment 2 (motor torque fluctuation | variation) of this invention. It is a time chart which shows the variable process of the switching speed of the semiconductor element for electric power by Embodiment 3 (motor output fluctuation | variation) of this invention. It is a figure which shows the structure (for 1 arm) of the gate drive circuit by Embodiment 4-10 of this invention. It is a time chart which shows the variable process of the switching speed of the semiconductor element for electric power by Embodiment 5 (inverter output current fluctuation | variation) of this invention. It is a time chart which shows the variable process of the switching speed of the semiconductor element for electric power by Embodiment 6 (inverter output voltage fluctuation | variation) of this invention. It is a time chart which shows the variable process of the switching speed of the semiconductor element for electric power by Embodiment 7 (inverter input current fluctuation | variation) of this invention. It is a time chart which shows the variable process of the switching speed of the semiconductor element for electric power by Embodiment 8 (inverter input voltage fluctuation | variation) of this invention. It is a time chart which shows the variable process of the switching speed of the power semiconductor element by Embodiment 9 (temperature fluctuation of a power semiconductor element) of this invention. It is a time chart which shows the variable process of the switching speed of the semiconductor element for electric power by Embodiment 10 (motor drive state fluctuation | variation) of this invention. It is a figure which shows the structure (for 1 arm) of the gate drive circuit by Embodiment 11 of this invention.

  Embodiments of a gate drive circuit according to the present invention will be described below with reference to the accompanying drawings.

Embodiment 1 FIG.
The gate drive circuit of the present invention is used, for example, as a part of the power conversion system shown in FIG. FIG. 1 will be briefly described. 200 is an electric motor for power running / regeneration (for example, a permanent magnet AC synchronous motor), 300 is a chargeable / dischargeable power storage device (for example, lithium ion battery, nickel metal hydride battery, electric double layer capacitor), and 100 is an electric motor for power running. Inverter device that converts supply power from direct current to alternating current and converts the regenerative power of the motor from alternating current to direct current during regeneration, 120 is a voltage-driven power semiconductor element (for example, IGBT, MOSFET), and 130 is a power semiconductor element 110 is a diode connected in reverse parallel, 110 is a gate drive circuit for driving the power semiconductor element, 140 is a control circuit for switching control of the power semiconductor element, and 150 is a smoothing capacitor for removing the ripple on the bus. is there.

  Hereinafter, the gate drive circuit according to the first embodiment of the present invention will be described with reference to the drawings. Inverter device 100 has a total of six arms, but the basic operation is the same. Therefore, for convenience of explanation, one arm portion of inverter device 100 shown in FIG. The power exchange system in FIG. 1 is common to the following embodiments.

FIG. 2 shows a configuration (for one arm) of the gate drive circuit 110 according to the first embodiment of the present invention. The gate drive circuit 110 is connected in series between the gate of the control circuit 140 and the power semiconductor element 120, a P NP bipolar transistor 112 having an emitter connected to the power semiconductor element control circuit 140, this P NP bipolar a resistor 113 connected between the emitter and base of transistor 112, to the connection point is the emitter of the base and the resistor 113 of the P NP bipolar transistor 112, the collector of the P NP bipolar transistor 112 the base, power semiconductors oN the P NP bipolar transistor 111 to the gate of the element 120 Ru is connected to the collectors, and a resistor 115 connected in parallel with the resistor 113, a resistor 113 and switch 116 to the connection / disconnection between the resistor 115, the switch 116 ON / OFF judgment circuit 1 to turn on / off Consisting of 7. Now, it is assumed that the switch 116 is OFF.

  In operation, when the power semiconductor element 120 is turned on, a base current flows through the second PNP bipolar transistor 111 via the resistors 113 and 114 when an ON signal is input from the control circuit 140 to the gate drive circuit 110. As a result, the second PNP bipolar transistor 111 becomes conductive, and the gate current ig that flows to the gate terminal of the power semiconductor element 120 flows through the resistor 113 and the second PNP bipolar transistor 111.

  When the gate current ig increases and the voltage drop across the resistor 113 exceeds the base-emitter threshold voltage of the first PNP bipolar transistor 112, the first PNP bipolar transistor 112 becomes conductive. As a result, the base and emitter of the second PNP bipolar transistor 111 are short-circuited, so that the second PNP bipolar transistor 111 is cut off.

  Such an operation is repeated, and the gate current ig flowing through the gate drive circuit 110 is limited with an upper limit of a value obtained by dividing the base-emitter voltage of the first PNP bipolar transistor 112 by the resistor 113.

  As described above, when the gate driving circuit according to the present invention is used, the gate current ig rises rapidly when a constant voltage is applied to the power semiconductor element 120 generated in the conventional constant voltage type gate driving circuit (not shown). Therefore, noise can be reduced. In addition, since the power semiconductor element 120 is driven at a constant current, the switching speed can be increased more than in the case of the conventional constant voltage drive, so that the switching loss of the power semiconductor element 120 can also be reduced.

  Next, switching processing for switching speed of power semiconductor element 120 in the first embodiment of the present invention will be described.

  In the first embodiment, the resistance value of the resistor 113 connected between the control circuit 140 and the emitter of the second PNP bipolar transistor 111 is switched based on the rotational speed of the motor 200 connected to the inverter device 100. Thus, the switching speed of the power semiconductor element 120 is switched.

  Here, since the noise and surge voltage generally increase as the motor speed increases, the switching speed of the power semiconductor element 120 takes into account that the motor operates at the maximum speed in order to suppress them. Need to be determined. For this reason, when the motor is operated at a low speed, the switching speed of the power semiconductor element 120 is excessively lowered.

  The rotation speed of the motor 200 is detected by a position sensor (not shown) such as a resolver or a rotation angle sensor (not shown), for example. Based on these detection signals (not shown), ON / OFF determination of the switch 116 is determined by the ON / OFF determination circuit 117, and the switch 116 is turned ON or OFF.

  When the switch 116 is ON, the resistor 113 and the resistor 115 are connected in parallel, so that the combined resistance is lower than when the switch 116 is OFF. For this reason, the limit value of the gate current ig flowing through the gate drive circuit 110 increases, the speed at which the gate capacitance of the power semiconductor element 120 is charged increases, and the switching speed increases.

  FIG. 3 illustrates switching speed switching processing in the present embodiment. 3a shows the transition of the motor speed, FIG. 3b shows the transition of the ON / OFF state of the switch 116, and FIG. 3c shows the transition of the switching speed. As shown in the figure, when the motor speed is high, the switch 116 is turned off to lower the switching speed, and when the motor speed is low, the switch 116 is turned on to increase the switching speed.

  According to the first embodiment described above, it is possible to reduce the switching loss of the power semiconductor element 120 when the motor rotates at a low speed while reducing the noise when the power semiconductor element 120 is turned on.

Embodiment 2. FIG.
A gate drive circuit according to the second embodiment of the present invention is also shown in FIG. That is, based on the torque of the motor 200 connected to the inverter device 100, the control circuit 140 and by switching the resistance value of the second PNP bipolar resistor is connected between the emitter capacitor of the transistor 111 113, power semiconductor The switching speed of the element 120 is switched.

  Here, since the noise and surge voltage generally increase as the motor torque increases, the switching speed of the power semiconductor element 120 is determined in consideration of operating the motor at the maximum torque in order to suppress these. There is a need to. For this reason, when the motor is operated at a low torque, the switching speed of the power semiconductor element 120 is excessively lowered.

  The torque of the motor 200 is detected by, for example, a torque sensor (not shown). Here, the motor torque may be a target torque received from a host controller (not shown) of the inverter device 100. Based on these detection signals (not shown), ON / OFF determination of the switch 116 is determined by the ON / OFF determination circuit 117, and the switch 116 is turned ON or OFF.

  When the switch 116 is ON, the resistor 113 and the resistor 115 are connected in parallel, so that the combined resistance is lower than when the switch 116 is OFF. For this reason, the limit value of the gate current ig flowing through the gate drive circuit 110 increases, the speed at which the gate capacitance of the power semiconductor element 120 is charged increases, and the switching speed increases.

  FIG. 4 illustrates switching speed switching processing according to the second embodiment. 4a shows the transition of the motor torque, FIG. 4b shows the transition of the ON / OFF state of the switch 116, and FIG. 4c shows the transition of the switching speed.

  As shown in the figure, when the motor torque is high, the switch 116 is turned off to lower the switching speed, and when the motor torque is low, the switch 116 is turned on to increase the switching speed.

  According to the second embodiment described above, it is possible to reduce the switching loss of the power semiconductor element 120 when the motor is at low torque while reducing the noise when the power semiconductor element 120 is turned on.

Embodiment 3 FIG.
A gate drive circuit according to Embodiment 3 of the present invention is also shown in FIG. Based on the output of the motor 200 connected to the inverter device 100, the resistance value of the resistor connected between the control circuit 140 and the emitter of the second PNP bipolar transistor 111 is switched to switch the power semiconductor element 120. Switch speed.

  Here, since the noise and surge voltage generally increase as the motor output increases, the switching speed of the power semiconductor element 120 is determined in consideration of operating the motor at the maximum output in order to suppress these. There is a need to. For this reason, when the motor is operated at a low output, the switching speed of the power semiconductor element 120 is excessively lowered.

  The output of the motor 200 is calculated from, for example, detection values of a position sensor (not shown) and a torque sensor (not shown), or a current sensor (not shown) for measuring the input current of the inverter device 100 and the inverter device 100. It detects by the calculation from the detected value of the voltage sensor (not shown) which measures an input voltage.

  Here, the motor output may be a target output value or an estimated output value received from a host controller (not shown) of the inverter device 100. Based on these detection signals (not shown), ON / OFF determination of the switch 116 is determined by the ON / OFF determination circuit 117, and the switch 116 is turned ON or OFF.

  When the switch 116 is ON, the resistor 113 and the resistor 115 are connected in parallel, so that the combined resistance is lower than when the switch 116 is OFF. For this reason, the limit value of the gate current ig flowing through the gate drive circuit 110 increases, the speed at which the gate capacitance of the power semiconductor element 120 is charged increases, and the switching speed increases.

FIG. 5 illustrates switching speed switching processing in the present embodiment. 5a shows the transition of the motor output , FIG. 5b shows the transition of the ON / OFF state of the switch 116, and FIG. 5c shows the transition of the switching speed.

  As shown in the figure, when the motor output is high, the switch 116 is turned off to lower the switching speed, and when the motor output is low, the switch 116 is turned on to increase the switching speed.

  According to the third embodiment described above, it is possible to reduce the switching loss of the power semiconductor element 120 when the motor has a low output while reducing the noise when the power semiconductor element 120 is turned on.

Embodiment 4 FIG.
A gate drive circuit according to a fourth embodiment of the present invention will be described with reference to the drawings. FIG. 6 shows the configuration (for one arm) of the gate drive circuit according to the fourth embodiment of the present invention.

The gate drive circuit 110 is connected in series between the gate of the control circuit 140 and the power semiconductor element 120, a P NP bipolar transistor 112 having an emitter connected to the power semiconductor element control circuit 140, before Symbol P NP a resistor 113 connected between the emitter and base of the bipolar transistor 112, a capacitor 119 and a capacitor 1110 connected in parallel between the emitter and collector of P NP bipolar transistor 11 2, the P NP bipolar transistor 112 the connection point is the emitter of the base and the resistor 113, the base-collector is P NP bipolar transistor 112, a P NP bipolar transistor 111 to the gate of the power semiconductor element 120 is connected to the collectors, a capacitor 119 and a capacitor 11 10 includes a switch 118 that connects / disconnects 10 and an ON / OFF determination circuit 117 that turns ON / OFF the switch 118.

  When the power semiconductor element 120 is turned on, when an on signal is input from the control circuit 140 to the gate drive circuit 110, a base current flows through the second PNP bipolar transistor 111 via the resistors 113 and 114. As a result, the second PNP bipolar transistor 111 becomes conductive, and the gate current ig flowing to the gate terminal of the power semiconductor element 120 flows through the resistor 113 and the second PNP bipolar transistor 111. At this time, since the capacitor 1110 is charged by the voltage drop of the resistor 113, the rise of the gate current ig is suppressed.

  When the gate current ig increases and the voltage drop across the resistor 113 exceeds the base-emitter voltage of the first PNP bipolar transistor 112, the first PNP bipolar transistor 112 becomes conductive. As a result, the base and emitter of the second PNP bipolar transistor 111 are short-circuited, and the second PNP bipolar transistor 111 is cut off. The gate current ig flowing through the gate driving circuit 110 by repeating such an operation is limited to an upper limit of a value obtained by dividing the base-emitter voltage of the first PNP bipolar transistor 112 by the resistor 113.

  As described above, when the gate drive circuit of the present invention is used, the steep rise of the gate current ig when the constant voltage is applied to the power semiconductor element 120 generated in the conventional constant voltage gate drive (not shown) can be obtained. Since it can be suppressed, noise can be reduced. In addition, since the power semiconductor element 120 is driven at a constant current, the switching speed can be increased more than in the case of the conventional constant voltage drive, so that the switching loss of the power semiconductor element 120 can also be reduced.

  Next, switching processing of the switching speed of the power semiconductor element 120 according to the fourth embodiment of the present invention will be described.

  In the fourth embodiment, the capacitance of the capacitor connected between the control circuit 140 and the base of the second PNP bipolar transistor 111 is switched based on the output current to the motor 200 connected to the inverter device 100. Thus, the switching speed of the power semiconductor element 120 is switched.

  Here, since the noise and surge voltage generally increase when the inverter output current increases, the switching speed of the power semiconductor element 120 must be determined in consideration of the maximum output current of the inverter in order to suppress these. is there. For this reason, when the inverter output current is low, the switching speed of the power semiconductor element 120 is excessively lowered.

  The inverter output current is detected by, for example, a current sensor (not shown). Based on this detection signal (not shown), ON / OFF determination of the switch 118 is determined by the ON / OFF determination circuit 117, and the switch 118 is turned ON or OFF.

  Since the capacitor 119 and the capacitor 1110 are connected in parallel when the switch 118 is ON, the combined capacitance increases as compared to the case where the switch 118 is OFF. For this reason, the rise of the gate current ig flowing through the gate driving circuit 110 is delayed, the speed at which the gate capacitance of the power semiconductor element 120 is charged is slowed, and the switching speed is lowered.

  FIG. 7 illustrates switching speed switching processing in the present embodiment. 7a shows the transition of the inverter output current, FIG. 7b shows the transition of the ON / OFF state of the switch 118, and FIG. 7c shows the transition of the switching speed.

  As shown in the figure, when the inverter output current is high, the switch 118 is turned on to lower the switching speed, and when the inverter output current is low, the switch 118 is turned off to increase the switching speed.

  According to the fourth embodiment described above, it is possible to reduce the switching loss of the power semiconductor element 120 when the inverter output current is low while reducing the noise when the power semiconductor element 120 is turned on.

Embodiment 5 FIG.
A gate drive circuit according to Embodiment 5 of the present invention is also shown in FIG. Based on the inverter output voltage to the motor 200 connected to the inverter device 100, the capacitance of the capacitor connected between the control circuit 140 and the base of the second PNP bipolar transistor 111 is switched, thereby allowing the power semiconductor The switching speed of the element 120 is switched.

  Here, since the noise and surge voltage generally increase when the inverter output voltage increases, the switching speed of the power semiconductor element 120 needs to be determined in consideration of the maximum output voltage of the inverter in order to suppress these. is there. For this reason, when the inverter output voltage is low, the switching speed of the power semiconductor element 120 is excessively lowered.

  The inverter output voltage is detected by, for example, a voltage sensor (not shown). Based on these detection signals (not shown), ON / OFF determination of the switch 118 is determined by the ON / OFF determination circuit 117, and the switch 118 is turned ON or OFF. Since the capacitor 119 and the capacitor 1110 are connected in parallel when the switch 118 is ON, the combined capacitance increases as compared to the case where the switch 118 is OFF. For this reason, the rise of the gate current ig flowing through the gate driving circuit 110 is delayed, the speed at which the gate capacitance of the power semiconductor element 120 is charged is slowed, and the switching speed is lowered.

FIG. 8 illustrates switching speed switching processing in the present embodiment. Figure 8a transition of the inverter output voltage, Figure 8b transition of ON / OFF state of the switch 118, Figure 8c shows the transition of the switching speed.

  As shown in the figure, when the inverter output voltage is high, the switch 118 is turned on to lower the switching speed, and when the inverter output voltage is low, the switch 118 is turned off to increase the switching speed.

  According to the fifth embodiment described above, it is possible to reduce the switching loss of the power semiconductor element 120 when the inverter output voltage is low while reducing the noise when the power semiconductor element 120 is turned on.

Embodiment 6 FIG.
A gate drive circuit according to Embodiment 6 of the present invention is also shown in FIG. That is, by switching the capacitance of the capacitor connected between the control circuit 140 and the base of the second PNP bipolar transistor 111 based on the inverter input current from the battery 300 connected to the inverter device 100, the power The switching speed of the semiconductor device 120 is switched.

  Here, since the noise and surge voltage generally increase when the inverter input current increases, the switching speed of the power semiconductor element 120 needs to be determined in consideration of the maximum input current of the inverter in order to suppress these. is there. For this reason, when the inverter input current is low, the switching speed of the power semiconductor element 120 is excessively lowered.

  The inverter input current is detected by, for example, a current sensor (not shown). Based on these detection signals (not shown), ON / OFF determination of the switch 118 is determined by the ON / OFF determination circuit 117, and the switch 118 is turned ON or OFF.

  Since the capacitor 119 and the capacitor 1110 are connected in parallel when the switch 118 is ON, the combined capacitance increases as compared to the case where the switch 118 is OFF. For this reason, the rise of the gate current ig flowing through the gate driving circuit 110 is delayed, the speed at which the gate capacitance of the power semiconductor element 120 is charged is slowed, and the switching speed is lowered.

FIG. 9 illustrates switching speed switching processing in the sixth embodiment. Figure 9a transition of the inverter input current, Figure 9b transition of ON / OFF state of the switch 118, Figure 9c shows the transition of the switching speed. As shown in the figure, when the inverter input current is high, the switch 118 is turned on to lower the switching speed, and when the inverter input current is low, the switch 118 is turned off to increase the switching speed.

  According to the sixth embodiment described above, it is possible to reduce the switching loss of the power semiconductor element 120 when the inverter input current is low while reducing the noise when the power semiconductor element 120 is turned on.

Embodiment 7 FIG.
A gate drive circuit according to Embodiment 7 of the present invention is also shown in FIG. That is, by switching the capacitance of the capacitor connected between the control circuit 140 and the base of the second PNP bipolar transistor 111 based on the inverter input voltage from the battery 300 connected to the inverter device 100, the power The switching speed of the semiconductor device 120 is switched. Here, although the inverter input voltage is the voltage of the battery 300, a DC / DC converter is installed between the inverter device 100 and the battery 300, and the inverter input voltage is the output voltage of the DC / DC converter. It doesn't matter.

  Here, generally, when the inverter input voltage increases, the voltage applied to the power semiconductor element 120 increases. In order to suppress this, it is necessary to determine the switching speed of the power semiconductor element 120 in consideration of the maximum input voltage of the inverter. For this reason, when the inverter input voltage is low, the switching speed of the power semiconductor element 120 is excessively lowered.

  The inverter input voltage is detected by, for example, a voltage sensor (not shown). Based on this detection signal (not shown), ON / OFF determination of the switch 118 is determined by the ON / OFF determination circuit 117, and the switch 118 is turned ON or OFF.

  Since the capacitor 119 and the capacitor 1110 are connected in parallel when the switch 118 is ON, the combined capacitance increases as compared to the case where the switch 118 is OFF. For this reason, the rise of the gate current ig flowing through the gate driving circuit 110 is delayed, the speed at which the gate capacitance of the power semiconductor element 120 is charged is slowed, and the switching speed is lowered.

FIG. 10 illustrates switching speed switching processing in the present embodiment. 10a shows the transition of the inverter input voltage , FIG. 10b shows the transition of the ON / OFF state of the switch 118, and FIG. 10c shows the transition of the switching speed. As shown in the figure, when the inverter input voltage is high, the switch 118 is turned on to lower the switching speed, and when the inverter input voltage is low, the switch 118 is turned off to increase the switching speed.

  According to the seventh embodiment described above, it is possible to reduce the switching loss of the power semiconductor element 120 when the inverter input voltage is low while reducing the noise when the power semiconductor element 120 is turned on.

Embodiment 8 FIG.
A gate drive circuit according to the eighth embodiment of the present invention is also shown in FIG. That is, by switching the capacitance of the capacitor connected between the control circuit 140 and the base of the second PNP bipolar transistor 111 based on the temperature of the power semiconductor element 120 mounted on the inverter device 100, the power The switching speed of the semiconductor device 120 is switched.

  Here, generally, when the temperature of the power semiconductor element increases, the surge voltage increases, and the withstand voltage of the power semiconductor element itself decreases, so that the switching speed of the power semiconductor element 120 is It is necessary to determine the temperature in consideration. For this reason, when the temperature of the power semiconductor element is high, the switching speed of the power semiconductor element 120 is excessively lowered.

  The temperature of the power semiconductor element 120 is detected by, for example, a temperature sensor (not shown). Based on these detection signals (not shown), ON / OFF determination of the switch 118 is determined by the ON / OFF determination circuit 117, and the switch 118 is turned ON or OFF.

  Since the capacitor 119 and the capacitor 1110 are connected in parallel when the switch 118 is ON, the combined capacitance increases as compared to the case where the switch 118 is OFF. For this reason, the rise of the gate current ig flowing through the gate driving circuit 110 is delayed, the speed at which the gate capacitance of the power semiconductor element 120 is charged is slowed, and the switching speed is lowered.

  FIG. 11 illustrates switching speed switching processing according to the present embodiment. 11a shows a change in temperature of the power semiconductor element, FIG. 11b shows a change in ON / OFF state of the switch 118, and FIG. 11c shows a change in switching speed. As shown in the figure, when the temperature of the power semiconductor element is low, the switch 118 is turned on to lower the switching speed, and when the temperature of the power semiconductor element is high, the switch 118 is turned off to increase the switching speed.

  According to the eighth embodiment described above, the switching loss of the power semiconductor element 120 when the temperature of the power semiconductor element 120 is high is reduced while reducing the noise when the power semiconductor element 120 is turned on. Can do.

Embodiment 9 FIG.
A gate drive circuit according to the ninth embodiment of the present invention is also shown in FIG. That is, by switching the capacitance of the capacitor connected between the control circuit 140 and the base of the second PNP bipolar transistor 111 based on the power running / regenerative operation state of the motor 200 connected to the inverter device 100. The switching speed of the power semiconductor element 120 is switched.

  Here, since the applied voltage of the power semiconductor element is generally higher when the motor is regenerating than when it is powering, the switching speed of the power semiconductor element 120 is the powering / regenerative operation of the motor. It is necessary to decide in consideration of the situation. For this reason, when the motor is powering, the switching speed of the power semiconductor element 120 is excessively lowered.

  The operating state of the motor power running / regeneration can be determined by, for example, the sign of the current detected by a current sensor (not shown) of the inverter device. Based on this detection signal (not shown), ON / OFF determination of the switch 118 is determined by the ON / OFF determination circuit 117, and the switch 118 is turned ON or OFF.

  Since the capacitor 119 and the capacitor 1110 are connected in parallel when the switch 118 is ON, the combined capacitance increases as compared to the case where the switch 118 is OFF. For this reason, the rise of the gate current ig flowing through the gate driving circuit 110 is delayed, the speed at which the gate capacitance of the power semiconductor element 120 is charged is slowed, and the switching speed is lowered.

  FIG. 12 illustrates switching speed switching processing according to the ninth embodiment. 12a shows the transition of the operating state of the power running / regeneration of the motor, FIG. 12b shows the transition of the ON / OFF state of the switch 118, and FIG. 12c shows the transition of the switching speed. As shown in the figure, when the motor operating state is regenerative, the switch 118 is turned on to lower the switching speed, and when the motor operating state is power running, the switch 118 is turned off to increase the switching speed.

  According to the ninth embodiment described above, it is possible to reduce the switching loss of the power semiconductor element 120 when the operation state of the motor is powering while reducing the noise when the power semiconductor element 120 is turned on. it can.

Embodiment 10 FIG.
It will be apparent to those skilled in the art that a more effective effect can be obtained by determining the switching speed of the power semiconductor element by combining the parameters described in the first to ninth embodiments. Therefore, detailed description is omitted.

Embodiment 11 FIG.
The combination of the variable resistance circuit shown in FIG. 3 and the variable capacitance circuit shown in FIG. 6 with the gate drive circuit 110 of the first to tenth embodiments described above can provide more effects. It will be clear to the contractor. Therefore, detailed description is omitted.

Embodiment 12 FIG.
In the gate drive circuit 110 of the above-described first to eleventh embodiments, as shown in FIG. 13, similar effects can be obtained by using an NPN bipolar transistor instead of the PNP bipolar transistor.

That is, in the embodiment of a gate drive circuit shown in FIG. 2, the emitter of the second NPN bipolar transistor as the second switch element is connected to the gate of the power semiconductor device, of the second NPN bipolar transistor base - variable resistor is connected between the emitter, the first NPN bipolar transistor as a first switching element, a connection point between the base and the variable resistor portion of the second NPN bipolar transistor emitter, the second The collector of the NPN bipolar transistor is connected to the collector and the control circuit is connected to the collector, and the determination circuit has a resistance value determined by ON / OFF of a part of the resistors in the variable resistor portion configured by a resistor parallel circuit. Can be changed.

Further, in the embodiment of a gate drive circuit shown in FIG. 6, the emitter of the second NPN bipolar transistor as the second switch element is connected to the gate of the power semiconductor device, of the second NPN bipolar transistor base - resistor between the emitter connected, a first NPN bipolar transistor as a first switching element, a connection point between the base and the resistance of the second NPN bipolar transistor to the emitter of the second NPN bipolar transistor The collector is connected to the base, the control circuit is connected to the collector, the variable capacitor section is connected between the collector and the emitter of the second NPN bipolar transistor, and the determination circuit is configured by a parallel circuit of capacitors. ON / OFF of some capacitors in the variable capacitor section Ri can be changed capacitance value.

Further, in the embodiment of a gate drive circuit shown in FIG. 13, the emitter of the second NPN bipolar transistor as the second switch element is connected to the gate of the power semiconductor device, of the second NPN bipolar transistor base - variable resistor is connected between the emitter, the first NPN bipolar transistor as a first switching element, a connection point between the base and the variable resistor portion of the second NPN bipolar transistor to the emitter, the second The collector of the NPN bipolar transistor is connected to the base, the control circuit is connected to the collector, the variable capacitor is connected between the collector and the emitter of the second NPN bipolar transistor, and the determination circuit is constituted by a parallel circuit of resistors. The resistance value is changed by turning on / off some of the resistors in the variable resistance section. It is allowed, and / or it is possible to change the capacitance value by ON / OFF of a part of the capacitor of the variable capacitor unit including a parallel circuit of a capacitor.

Embodiment 13 FIG.
In the first to twelfth embodiments described above, the switching speed of the power semiconductor element is changed discontinuously, but it goes without saying that the same effect can be obtained even if this is changed continuously.
That is, in the embodiment shown in FIG. 2, not only the mechanical characteristic values of the motor, but also the inverter input / output / current / voltage , the power semiconductor element temperature or the motor in the embodiment shown in FIG. The present invention is applicable to the power running / regenerative state, and not only the power running / regenerative state of the inverter, the power semiconductor element or the motor in the embodiment shown in FIG. 6, but also the embodiment shown in FIG. The present invention can also be applied to mechanical characteristic values of motors.

  In the above first to thirteenth to thirteenth embodiments, when the motor has a high load, the control is performed so as to reduce the switching speed with an emphasis on low noise, but this may be reversed. In the future, when a low-loss power semiconductor element (for example, SiC) or the like is applied, it is possible to further optimize the balance between low noise and efficiency (loss).

  The power semiconductor element may be made of a non-Si semiconductor material having a wider band gap than silicon, and the non-Si semiconductor material may be silicon carbide, a gallium nitride-based material, or diamond.

  100 inverter device, 110 gate drive circuit, 111 bipolar transistor, 111n bipolar transistor, 112 bipolar transistor, 112n bipolar transistor, 113 resistor, 113n resistor, 115 resistor, 115n resistor, 116 switch, 116n switch, 117 determination circuit, 117n determination circuit , 118 switch, 118n switch, 119 capacitor, 119n capacitor, 120 power semiconductor element, 140 power semiconductor element control circuit, 200 motor, 300 battery, 1110 capacitor, 1110b capacitor.

Claims (13)

In a gate drive circuit of a voltage-driven power semiconductor element mounted on an inverter for driving a motor with an alternating current,
A current variable unit that changes a charging current when the gate of the power semiconductor element is charged with a constant current from the control circuit;
A determination circuit that controls the current variable unit to change the switching speed of the power semiconductor element so that noise is reduced according to the load state or drive state of the motor detected by a sensor;
The current variable unit is a resistor provided in the charging current path, a variable capacitor unit whose capacitance value is controlled by the determination circuit, and the charge current for the power when connected to the resistor and in an ON state. A first switch element that is applied to a semiconductor element and connected in parallel with the variable capacitor portion to the resistor, and when the first switch element is in an ON state, the resistor and the first switch are turned on by a voltage drop of the resistor. And a second switch element that short-circuits the switch element and controls the first switch element to OFF. In a gate drive circuit of a voltage-driven power semiconductor element mounted on an inverter for driving a motor with an alternating current,
A current variable unit that changes a charging current when the gate of the power semiconductor element is charged with a constant current from the control circuit;
A determination circuit that controls the current variable unit to change the switching speed of the power semiconductor element so that noise is reduced according to the load state or drive state of the motor detected by a sensor;
The current variable section is connected to the variable resistance section provided in the path of the charging current and is connected to the variable resistance section to supply the charging current to the power semiconductor element and to be variable to the variable resistance section. A first switch element that connects the capacitor units in parallel; and when the first switch element is in an ON state, the first switch element is turned on by a voltage drop of the variable resistor unit; the first switch element, the variable resistor unit, and the variable And a second switch element that controls the first switch element to OFF by short-circuiting a capacitor section, and the variable resistance section and the variable capacitor section are controlled by the determination circuit. The gate drive circuit according to claim 1 or 2 ,
The first and second switch elements are first and second PNP bipolar transistors or first and second NPN bipolar transistors, respectively. The gate drive circuit according to claim 2 ,
The determination circuit disconnects the variable capacitor unit when changing a resistance value of the variable resistor unit corresponding to a mechanical characteristic value indicating a load state of the motor, and the electrical circuit of the inverter indicating the load state A gate drive circuit that controls the resistance value of the variable resistor unit to be fixed at a constant value when the capacitance value of the variable capacitor unit is changed in response to a characteristic value. The gate drive circuit according to claim 1 ,
An emitter of a second PNP bipolar transistor as the second switch element is connected to the control circuit;
The resistor is connected between the emitter and base of the second PNP bipolar transistor;
The first PNP bipolar transistor as the first switch element has a connection point between the base of the second PNP bipolar transistor and the resistor as an emitter, and a collector of the second PNP bipolar transistor as a base. A gate of the power semiconductor element is connected to a collector, and the variable capacitor portion is connected between an emitter and a collector of the second PNP bipolar transistor;
The determination circuit changes a capacitance value by ON / OFF of a part of the capacitors in the variable capacitor unit configured by a parallel circuit of capacitors. The gate drive circuit according to claim 2 ,
An emitter of a second PNP bipolar transistor as the second switch element is connected to the control circuit;
The variable resistor is connected between an emitter and a base of the second PNP bipolar transistor;
The first PNP bipolar transistor as the first switching element has a connection point between the base of the second PNP bipolar transistor and the variable resistance portion as an emitter, and a collector of the second PNP bipolar transistor as a base. In addition, the gate of the power semiconductor element is connected to the collector,
The variable capacitor portion is connected between an emitter and a collector of the second PNP bipolar transistor;
The determination circuit is configured to change a resistance value by turning on / off a part of the resistors in the variable resistor unit configured by a parallel circuit of resistors, and / or the variable capacitor unit configured by a parallel circuit of capacitors. Gate drive circuit that changes the capacitance value by turning on / off some of the capacitors. The gate drive circuit according to claim 1 ,
An emitter of a second NPN bipolar transistor as the second switch element is connected to a gate of the power semiconductor element;
The resistor is connected between a base and an emitter of the second NPN bipolar transistor;
The first NPN bipolar transistor as the first switching element has a connection point between the base and the resistor of the second NPN bipolar transistor as an emitter, and a collector of the second NPN bipolar transistor as a base. Each of the control circuits is connected to a collector;
The variable capacitor section is connected between a collector and an emitter of the second NPN bipolar transistor;
A gate drive circuit in which the determination circuit changes a capacitance value by ON / OFF of a part of the capacitors in the variable capacitor unit configured by a parallel circuit of capacitors. The gate drive circuit according to claim 2 ,
An emitter of a second NPN bipolar transistor as the second switch element is connected to a gate of the power semiconductor element;
The variable resistor is connected between a base and an emitter of the second NPN bipolar transistor;
The first NPN bipolar transistor as the first switching element has a connection point between the base of the second NPN bipolar transistor and the variable resistance portion as an emitter, and a collector of the second NPN bipolar transistor as a base. And the control circuit is connected to the collector,
The variable capacitor section is connected between a collector and an emitter of the second NPN bipolar transistor;
The determination circuit is configured to change a resistance value by turning on / off a part of the resistors in the variable resistor unit configured by a parallel circuit of resistors, and / or the variable capacitor unit configured by a parallel circuit of capacitors. Gate drive circuit that changes the capacitance value by turning on / off some of the capacitors. The gate drive circuit according to claim 1 or 2 ,
The inverter is a three-phase inverter in which three half-bridge circuits in which two power semiconductor elements are connected in series are connected in parallel, and the motor is connected to an AC terminal of the three-phase inverter. . The gate drive circuit according to claim 1 ,
The electrical characteristic value of the inverter indicating the load state is output current, output voltage, input current, or input voltage,
The determination circuit changes the capacitance value of the variable capacitor unit to be lower as the electrical characteristic value of the inverter is lower, as the temperature of the power semiconductor element is lower, or when the motor is in a power running state. A gate drive circuit for changing a switching speed of the power semiconductor element high. The gate drive circuit according to claim 2 ,
The determination circuit changes the resistance value of the variable resistor unit lower to change the switching speed of the power semiconductor element higher and / or indicates the load state as the mechanical characteristic value of the motor is lower. When the electric characteristic value of the inverter is lower, the temperature of the power semiconductor element is higher, or when the motor is in a power running state, the capacitance value of the variable capacitor unit is changed to be lower and the power semiconductor element is changed. Gate drive circuit that changes the switching speed of the high. The gate drive circuit according to claim 1 or 2 ,
The power semiconductor element is made of a non-Si semiconductor material having a wider band gap than silicon. The gate drive circuit according to claim 12 ,
The non-Si semiconductor material is any one of silicon carbide, a gallium nitride-based material, and diamond.

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