JPH0541397U - Voltage type semiconductor device driver - Google Patents

Abstract

(57) [Abstract] [Purpose] To extend the operating voltage application time by the capacitor without supplying an unintended control signal to the voltage type semiconductor device. [Structure] A capacitor 5e is provided in parallel with a capacitor 5a charged by the DC power source 4 during the conduction period of the lower arm,
A changeover switch 5f is provided for selecting a state in which the capacitor 5e is connected in parallel with the capacitor 5a and a state in which the capacitor 5e is connected to the DC power supply 4 without the plate arm.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a voltage type semiconductor device driving device, and more specifically, a direct current control circuit for controlling each voltage type semiconductor device in an inverter configured by using voltage type semiconductor devices such as power MOSFETs and IGBTs. The present invention relates to a voltage type semiconductor element driving device suitable for applying an operating voltage from a power source.

[0002]

[Prior Art]

 Since the voltage type semiconductor device has a very small driving power, a bootstrap circuit using a capacitor as a temporary DC power source can be applied to simplify the driving circuit. FIG. 7 is an electric circuit diagram showing a conventional half-bridge inverter circuit, in which a pair of switch elements 91 and 92 made up of power MOSFETs are connected in series and based on an inverter control signal supplied from the outside. It has driver circuits 94 and 95 which supply a conduction instruction signal to a corresponding switch element based on a conduction control signal output from a control circuit (not shown) which outputs a conduction control signal. Then, a capacitor 97 is connected via a diode 96 between a DC power source 93 that applies an operating voltage to the driver circuit 95 of the lower arm and a connection point of both switch elements 91 and 92. The operating voltage is applied to the driver circuit 94 of the upper arm, and the operating voltage is applied to the driver circuit 95 of the lower arm by the DC power supply 93.

Therefore, an operating voltage is constantly applied to the driver circuit 95 of the lower arm by the DC power supply 93 to achieve the control of the switch element 92, and the diode 96 is applied through the diode 96 while the switch element 92 is conducting. The capacitor 97 to be charged applies an operating voltage to the driver circuit 94 of the upper arm to achieve the control of the switch element 91. That is, the configuration for applying the operating voltage to each driver circuit 94, 95 can be simplified.

[0004]

[Problems to be solved by the device]

 In the half-bridge inverter circuit configured as described above, the capacitor 97 for applying the operating voltage to the driver circuit 94 of the upper arm is charged only during the conduction period of the switch element 92 of the lower arm. The operation time of 91 is determined by the amount of electric charge accumulated in the capacitor 97, and there is a disadvantage that the upper arm switch element 91 cannot be controlled for a sufficiently long time as it is. Specifically, the amount of charge Qboot required to drive the upper arm is Qg, the amount of charge for charging the input capacitance of the switch element 91, the current of the driver circuit 94 is Iqbs, and the conduction period of the upper arm is Ton. Then, since the equation Qboot = Qg + Iqbs * Ton is obtained, the upper limit of the conduction period Ton of the upper arm is determined based on the capacitance of the capacitor 97. Generally, the capacity of the capacitor 97 is set so that the conduction period Ton of the upper arm is about several hundred microseconds.

In consideration of such inconvenience, in the conventional half-bridge inverter circuit, a timer is provided in the control circuit so as to be independent of the inverter control signal (see FIGS. 8A and 8B) supplied from the outside. It has been proposed that the switch element 92 of the lower arm be forcibly turned on every predetermined time (see the portion surrounded by the broken line in the timing chart of FIGS. 8C and 8D) to recharge the capacitor 97. ..

However, when the timer is provided to recharge the capacitor 97, a switching pattern unrelated to the inverter control signal supplied from the outside is output, and the distortion of the output voltage waveform increases. Therefore, it can be applied only to applications where accuracy is not required so much, and cannot be applied to applications where output voltage waveform must be controlled with high accuracy.

Although the above description has been given only to the case of being applied to the half-bridge inverter circuit, the same problem will occur when it is applied to the full-bridge inverter circuit or the like.

[0008]

[The purpose of the device]

 The present invention has been made in view of the above problems, and provides a voltage type semiconductor element driving device capable of controlling a voltage type semiconductor element for a desired time without increasing distortion of an output voltage waveform. It is an object.

[0009]

[Means for Solving the Problems]

 In order to achieve the above object, the voltage type semiconductor element driving device according to claim 1 includes a signal supply means for supplying a conduction state instruction signal to one of the voltage type semiconductor elements connected in series with each other. It is charged by a DC power supply through a DC power supply for applying an operating voltage, a pair of rectifying means and a voltage type semiconductor element controlled by one signal supplying means, and the operating voltage is applied to the other signal supplying means based on the accumulated charge. The first charge storage means, the second charge storage means having one terminal connected to the connection point of both rectification means, and the other terminal of the second charge storage means selected as the first charge storage means or the DC power supply. And switch means that are connected to each other.

[0010]

[Action]

 In the voltage type semiconductor element driving device according to claim 1, the signal supply means supplies a conduction state indicating signal to the voltage type semiconductor elements connected in series with each other to selectively bring the voltage type semiconductor elements into conduction. In this case, a DC power supply always applies an operating voltage to one of the signal supply means. Then, the operating voltage is applied to the other signal supply means by the first charge storage means charged by the DC power source through the voltage type semiconductor element controlled by the pair of rectifying means and one signal supply means. In this case, the time during which the corresponding voltage type semiconductor element can be controlled by the first charge storage means while the operating voltage is applied to the other signal supply means is determined by the stored charge amount. In (1), while the charge is being accumulated in the first charge accumulating means, the charge is also accumulated in the second charge accumulating means, and the charge accumulated in the second charge accumulating means is supplied to the first charge accumulating means. Therefore, it is possible to lengthen the time for which the voltage-type semiconductor element can be controlled without causing the voltage-type semiconductor element to perform unnecessary switch operation. Further, while the operating voltage is being applied to the signal supply means by the first charge storage means, the second charge storage means is controlled by controlling the switch means so as to connect the other terminal of the second charge storage means to the DC power supply. Since the charge can be stored in the means, the time for controlling the voltage type semiconductor device can be further extended.

[0011]

【Example】

 Embodiments will be described in detail below with reference to the accompanying drawings. FIG. 1 is an electric circuit diagram schematically showing the configuration of a half-bridge inverter to which the voltage type semiconductor device driving device of the present invention is applied. A voltage composed of a power MOS FET, an IGBT and the like is provided between terminals of a main DC power supply 1. Type semiconductor elements 2a and 2b are connected in series, and driver circuits 3a and 3b for supplying a conduction instruction signal to a corresponding voltage type semiconductor element based on an inverter control signal output from a control circuit (not shown) are provided. Has been. The lower arm driver circuit 3b is provided with an auxiliary DC power supply 4 for applying an operating voltage, and the upper arm driver circuit 3a is provided with a capacitor 5a as a first charge storage means for applying an operating voltage. ing. The capacitor 5a is charged by the auxiliary DC power supply 4 via the resistor 5b, the pair of diodes 5c and 5d and the lower arm voltage type semiconductor element 2b. Also, a capacitor 5e is provided as a second charge storage means, one terminal of which is connected to the connection point of the diodes 5c and 5d, and the other terminal of this capacitor 5e is connected to the auxiliary DC power source via the changeover switch 5f. 4 or both voltage type semiconductor elements 2a and 2b are selectively connected to the connection points.

The operation of the half bridge inverter circuit will be described with reference to FIGS. 2 to 5. When the changeover switch 5f is controlled so as to connect the other terminal of the capacitor 5e to the connection point between the voltage type semiconductor elements 2a and 2b, and the voltage type semiconductor element 2b of the lower arm is conducting, as shown in FIG. As shown by the broken line, the capacitor 5a is charged by the auxiliary DC power supply 4 through the diodes 5c and 5d and the lower arm voltage type semiconductor device 2b, and the capacitor 5e is charged by the auxiliary DC power supply 4 through the diode 5c and the lower arm voltage type semiconductor device 2b. To charge. Then, the operating voltage is also applied to the driver circuit 3a. Next, when the voltage-type semiconductor element 2b of the lower arm is cut off, the influence of the main DC power supply 1 is blocked by the diodes 5c and 5d, and the driver circuit 3a is connected to the driver circuit 3a by the capacitor 5a as shown by the broken line in FIG. Apply operating voltage. Since the capacitor 5e is connected in parallel with the capacitor 5a, it is equivalent to increasing the capacity of the capacitor 5a, and the operating voltage required to control the voltage-type semiconductor element 2a of the upper arm is increased. Can be applied to the driver circuit 3a for a long time.

When the changeover switch 5f is controlled to connect the other terminal of the capacitor 5e to the auxiliary DC power source 4 and the voltage type semiconductor element 2b of the lower arm is conducting, as shown by a broken line in FIG. In addition, the capacitor 5a is charged by the auxiliary DC power supply 4 through the diodes 5c and 5d and the voltage type semiconductor element 2b of the lower arm, and the capacitor 5e is charged by the auxiliary DC power supply 4 through the diode 5c. Then, the operating voltage is also applied to the driver circuit 3a. Next, when the voltage type semiconductor element 2b of the lower arm is cut off, the influence of the main DC power supply 1 is blocked by the diodes 5c and 5d, and the driver circuit 3a is connected to the driver circuit 3a by the capacitor 5a as shown by the broken line in FIG. Apply operating voltage. The charging of the capacitor 5e by the auxiliary DC power supply 4 continues as it is.

Therefore, when the conduction time of the voltage-type semiconductor element 2a of the upper arm becomes long, the state shown in FIG. 3 and the state shown in FIG. 5 may be repeated by controlling the changeover switch 5f. It is possible to continue the conduction of the upper arm voltage type semiconductor element 2a for a desired time without affecting the above.

[0015]

Second Embodiment FIG. 6 is an electric circuit diagram showing another embodiment of the present invention, showing a state in which it is applied to a three-phase inverter circuit. In FIG. 6, three sets of series circuits each including power MOSFETs 2a and 2b as a pair of voltage type semiconductor elements are connected in parallel to the main DC power supply 1. Insulated gate drive buffers 21a and 21b for supplying gate signals to the power MOSFETs 2a and 2b and PWM signal circuits 31a and 31b for supplying PWM signals to the insulated gate drive buffers 21a and 21b are provided. ing. Further, the auxiliary DC power supply 4 for applying the operating voltage to all the insulated gate drive buffers 21b of the lower arm, and the capacitor 5a as the first charge storage means for applying the operating voltage to each of the insulated gate drive buffers 21a of the upper arm. And are provided. A diode 5c and resistors 5b and 5g connected in series are connected in series with each capacitor 5a so that each capacitor 5a is charged by the main DC power supply 1. Furthermore, a capacitor 5e is provided as a second charge storage means, one terminal of which is connected to the connection point between the diode 5c and the capacitor 5a, and the other terminal of this capacitor 5e is connected via the changeover switch 5f. It is selectively connected to the connection point of the DC power supply 1 or the double-voltage type semiconductor elements 2a and 2b. Incidentally, 5h is a resistor connected between the changeover switch 5f and the main DC power supply 1, 5i is a constant voltage diode connected in parallel with the capacitor 5e, and 6 is a three-phase load.

The operation of the embodiment having the above configuration is as follows. When the power MOSFET 2a in the upper arm is in the conducting state, the potentials at both ends of the resistor 5g have the same potential as the main DC power supply 1, so that the capacitor 5a is not charged. However, in this case, since the capacitor 5e can be charged by performing the switching operation so that the changeover switch 5f is connected to the main DC power supply 1, the changeover switch 5f is set in the reverse state after charging. If the switching operation is performed in this manner, the capacitor 5e can be charged by the capacitor 5e. As a result, the constraint on the upper arm operation time due to the capacitor 5a can be eliminated.

The present invention is not limited to the above-described embodiments, but can be applied to, for example, a full-bridge inverter circuit, and various modifications can be made without departing from the scope of the invention. It is possible to make design changes.

[0018]

[Effect of the device]

 As described above, the invention of claim 1 interferes with the desired operation of the voltage type semiconductor element when the operating voltage is applied to the signal supply means by the charge storage means in order to control the voltage type semiconductor element. The practicable effect peculiar to the voltage-type semiconductor element can be continued for a desired time without supplying the control signal for controlling the voltage-type semiconductor element.

[Brief description of drawings]

FIG. 1 is an electric circuit diagram schematically showing a configuration of a half-bridge inverter to which a voltage type semiconductor device driving device of the present invention is applied.

FIG. 2 is a schematic diagram illustrating an operation when the changeover switch is controlled to connect the other terminal of the capacitor 5e to a connection point of both voltage type semiconductor elements and the voltage type semiconductor element of the lower arm is conductive. Is.

FIG. 3 is a schematic diagram illustrating an operation when the changeover switch is controlled to connect the other terminal of the capacitor 5e to a connection point of both voltage type semiconductor elements, and the voltage type semiconductor element of the lower arm is cut off. Is.

FIG. 4 is a schematic diagram illustrating an operation when the changeover switch is controlled to connect the other terminal of the capacitor 5e to the auxiliary DC power supply and the voltage type semiconductor element of the lower arm is conductive.

FIG. 5 is a schematic diagram illustrating an operation when the changeover switch is controlled to connect the other terminal of the capacitor 5e to the auxiliary DC power supply and the voltage type semiconductor element of the lower arm is cut off.

FIG. 6 is an electric circuit diagram showing a three-phase inverter circuit to which another embodiment of the present invention is applied.

FIG. 7 is an electric circuit diagram showing a conventional half-bridge inverter circuit.

FIG. 8 is a diagram showing a signal waveform of each part.

[Explanation of symbols]

2a, 2b Voltage type semiconductor element 3a, 3b Driver circuit 4 Auxiliary DC power supply 5a, 5e Capacitor 5
c, 5d diode 5f changeover switch

Claims (1)

[Scope of utility model registration request] 1. A voltage-type semiconductor element driving device comprising signal supply means (3a, 3b) for supplying a conduction state instruction signal to voltage-type semiconductor elements (2a, 2b) connected in series with each other. , A DC power source (4) for applying an operating voltage to one of the signal supply means (3b), a pair of rectifying means (5c, 5d), and a voltage type semiconductor element (1) controlled by the one signal supply means (3b). 2b) is charged by a DC power supply (4) and applies an operating voltage to the other signal supply means (3a) based on the accumulated charge, and a first charge storage means (5a) and one terminal of which has both rectification means (5c). , 5
Second charge storage means (5e) connected to the connection point of d)
And a switch means (5f) for selectively connecting the other terminal of the second charge storage means (5e) to the first charge storage means (5a) or the DC power supply (4). Semiconductor device driver.