JP2732155B2 - Switching element control device and device using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a switching element which performs high-speed on / off control by applying a positive voltage and a negative voltage to a control input terminal of the switching element such as a transistor. It is.

[0002]

2. Description of the Related Art In order to control on / off of a switching element such as a bipolar transistor at a high speed, positive and negative voltages are applied to a base which is a control input terminal. In this case, positive and negative power supplies to be applied to the base are required.

FIG. 7 is a circuit diagram of a conventional device, in which an AC power supply and a transformer are used for a power supply circuit of the base. In this figure, reference numeral 10 denotes an NPN bipolar transistor. For example, a plurality of the transistors 10 are combined to form a bridge circuit, and are used for a control circuit such as a servomotor or an inverter by high-speed switching. Reference numeral 12 denotes an AC power supply, and reference numeral 14 denotes an insulating transformer. The AC voltage on the secondary side of the transformer 14 is rectified by diodes 16 and 18, and charges the capacitors 20 and 22 to the illustrated polarity. The capacitor 20 is for a positive voltage source, and the positive electrode voltage is input to the base circuit 24.
Similarly, the capacitor 22 is for a negative voltage source, and the negative electrode voltage is input to the base circuit 24. The base circuit 24 turns on the transistor 10 at a duty ratio determined by a control command signal input from a circuit (not shown).
It turns off, but when it turns on, the positive voltage of the capacitor 20 is used, and when it turns off, the negative voltage of the capacitor 22 is used.

As described above, in the conventional circuit, the transistor 1
0 and an AC power supply 12
Transformer 14 is required because
There is a problem that the device becomes large and heavy. Further, when a bridge circuit is formed using this conventional circuit, crosstalk easily occurs between the secondary sides of the transformer 14 at the time of high-speed switching due to the stray capacitance of the transformer 14, thereby easily causing a malfunction. There was also a problem.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and uses a transformer when applying positive and negative voltages to a control input terminal of a switching element to turn on and off the switching element at high speed. It is an object of the present invention to provide a control device for a switching element which can be reduced in size and weight without causing any malfunction and hardly causes malfunction.

[0006]

According to the present invention, there is provided a switching element for performing on / off control by applying a positive voltage and a negative voltage to a control input terminal, comprising: a DC power supply connected in series to the switching element; together directly charged by the DC power supply at the time of off of the switching element
A column-connected positive voltage source capacitor and a control capacitor; a negative voltage source capacitor charged by a discharge current of the control capacitor discharged through the switching element when the switching element is turned on; A control input terminal circuit that controls a control input terminal of the switching element by using a positive electrode voltage of a voltage source capacitor and a negative electrode voltage of the negative voltage source capacitor. Achieved.

[0007]

FIG. 1 is a basic circuit diagram of the present invention. In this figure, reference numeral 30 denotes an insulating gate NPN as a switching element.
Type bipolar transistor and its collector (C)
Is the positive electrode (+) of the DC power supply, and the emitter (E) is grounded (-). Reference numeral 32 denotes a capacitor for a positive voltage source. The positive electrode (+) is connected to the collector (C) via the resistor 34 and the diode 36, and the negative electrode (-) is connected to the emitter (E).

A control capacitor 38 has a positive electrode (+) connected to the collector (C) and a negative electrode (-) connected to the positive electrode (+) of the capacitor 32 via a diode 40. Reference numeral 42 denotes a capacitor for a negative voltage source, the positive electrode of which is connected to the emitter (E), and the negative electrode (-) of which is connected to the negative electrode (-) of the capacitor 38 via the diode 44. Note that zener diodes 46 and 48 are connected in parallel to the capacitors 32 and 42, respectively.
The charging voltages of 2, 42 are kept constant.

A positive electrode (+) of the capacitor 32 and a negative electrode (-) of the capacitor 42 are input to the base circuit 50, and a connection point between the capacitors 32 and 42 is input as a common voltage. The base circuit 50 turns on / off the transistor 30 at a predetermined duty ratio based on a command signal i input from a circuit (not shown). When the base circuit 50 is turned on, the positive electrode voltage of the capacitor 32 is used. The switching speed is increased by applying a negative electrode voltage and sucking out the current accumulated in the base while the switch is on.

Next, the operation of this circuit will be described. First, while the transistor 30 is off, the diode 36 and the resistor 34
, A charging current of the capacitor 32 flows, and the capacitor 32 is charged to the illustrated polarity. Also capacitor 3
8, the charging current flows through the diode 40, the Zener diode 46, or the capacitor 32, and is charged to the polarity shown. The solid line arrows in the figure indicate the current flow at this time. When turning on the transistor 30 based on the control command signal, the base circuit 50
A positive voltage is applied to the base using the positive electrode voltage (+) of No. 2.

At the moment when the transistor 30 is turned on,
The capacitor 38 includes the transistor 30, the capacitor 42,
Discharged through the diode 44, the capacitor 42 is charged to the polarity shown. The dashed arrow in the figure indicates the direction of current flow at this time. Then, when the base circuit 50 turns off the transistor 30, the negative electrode voltage (-) of the capacitor 42 is applied to the base to enable the transistor 30 to turn off at high speed. By repeating the above operation, extremely high-speed switching becomes possible. The diode 36 is for preventing the capacitor 32 from being discharged at the moment when the transistor 30 is turned on, thereby preventing unnecessary consumption of the battery.

FIG. 2 is a diagram showing a practical circuit based on the basic circuit of FIG. In this circuit, MOSFET (insulated gate field effect transistor) 3 suitable for high-speed switching
0A is used. In addition, a series regulator is configured using the NPN transistor 60 in order to reduce the loss of the resistor 34. That is, the current value of the resistor 34 is reduced by the current amplification factor of the transistor 60 to reduce this loss. When the charging of the capacitor 32 is completed, the emitter voltage of the transistor 60 rises.
Turns off.

62 and 64 are Zener diodes 46 and 4
8 is a transistor for increasing the allowable loss.
66 and 68 are bypass capacitors connected in parallel to the capacitors 32 and 42, and reduce the impedance of the capacitors 32 and 42.

As is apparent from the above description, a single-phase or three-phase bridge circuit can be constructed by combining a plurality of the devices of the present invention, and various types of devices such as a servo motor speed control device and an inverter device can be used by using the bridge circuit. It can be used for devices. It can also be applied to power supplies such as switching regulators. In short, the present invention is applicable to a circuit that switches a switching element at high speed, and the present invention includes these.

FIG. 3 is a block diagram of a three-phase bridge circuit as an example using the control device shown in FIGS. In this figure, reference numeral 30 is the same as the transistor 30 in FIG. 1, and C indicates the entire circuit including the base circuit 50 or the gate circuit 50A and the capacitors 32, 38, 42 and the like in FIGS. Each circuit C has a command signal u for each phase.
^{+, U -, v +,} v -, w +, w - is input to the predetermined timing, the transistor 30 is selectively turned on and off control.

FIG. 4 is a circuit diagram showing a servomotor speed control device using the control circuit shown in FIGS. In this figure, reference numeral 100 denotes, for example, a DC servomotor, and the rotation speed v of the rotor is detected by a tacho generator 102. Deviation between the rotational speed v and the speed command v _i (v
_i -v) is obtained by the differential amplifier 104, the speed deviation (v _i -v) pulse width control circuit in response to (PWM) 1
Reference numeral 06 outputs a command signal i having a predetermined pulse width at a predetermined timing. 108 is a triangular wave oscillator PWM106 speed deviation triangular wave output from the oscillator 108 (v _i -
The output phase and the pulse width of the command signal i are determined by comparing with v).

The command signal i is transmitted to the positive-phase control circuit C of each phase.
In addition, the inverted signal i of the command signal i obtained through the inverter 110 is input to the control circuit C of the opposite phase of each phase, and turns on / off the transistor 30 of each phase. In this figure, 112 is a battery, and 114 is a diode connected in anti-parallel to each transistor 30. In this figure, a single phase is described, but it is needless to say that three phases may be used.

FIG. 5 is a diagram showing an inverter circuit using the circuits of FIGS. In this figure, 120 is an oscillator,
A command signal i having a predetermined frequency and a predetermined pulse width is supplied to a positive-phase control circuit C, and its inverted signal i is supplied to a negative-phase control circuit C. As a result, a primary current flows on the primary side of the output transformer 122 at the frequency of the command signal i, and an AC voltage v ₀ having the same frequency is obtained on the secondary side. In this figure, the same parts as those in FIG. 4 are denoted by the same reference numerals.

FIG. 6 is a diagram showing a switching regulator using the circuits of FIGS. In this Figure 130 is a comparator, its a non-inverting input terminal a reference voltage v ₁ was obtained by the constant voltage diode 132 and to the inverting input terminal is inputted a voltage v ₂ which is proportional to the output voltage v ₀ . Therefore, when v ₁ > v ₂ , the comparator 130 outputs a positive command signal i to the circuit C, and the transistor 30 is turned on. Conversely, when v ₁ <v ₂ , the transistor 30 is turned off, and the output voltage v ₀ is controlled to be constant.

[0020]

As described above, the present invention charges the positive voltage source capacitor and the control capacitor when the switching element is turned off, and discharges the control capacitor via the switching element at the moment when the switching element is turned on. Thus, the capacitor for the negative voltage source is charged, and switching is performed using the positive and negative voltages of the capacitors for the positive and negative voltage sources. Therefore, high-speed switching can be performed without using a transformer. Therefore, the device can be reduced in size and weight. Since no transformer is used, there is no problem of crosstalk between output coils on the secondary side of the transformer, and there is no fear of malfunction due to crosstalk. According to the second aspect of the present invention, since the discharge of the positive voltage source capacitor is restricted when the switching element is turned on, power consumption is reduced and efficiency is improved. The switching element is suitably an NPN transistor or a MOS FET (claims 3 and 4). Also, a bridge circuit, a speed control device for a servomotor, an inverter device, a switching regulator, and the like can be configured by using the control device (claims 5 to 8).

[Brief description of the drawings]

FIG. 1 is a basic circuit diagram of the present invention.

FIG. 2 is a practical circuit diagram of the present invention.

FIG. 3 is a bridge circuit diagram using the control device of the present invention.

FIG. 4 is a circuit diagram of a servo motor speed controller.

FIG. 5 is an inverter circuit diagram.

FIG. 6 is a switching regulator circuit diagram.

FIG. 7 is a circuit diagram of a conventional device.

[Explanation of symbols]

 Reference Signs List 30 Transistor as switching element 30A FET as switching element 38 Control capacitor 42 Negative voltage source capacitor 50 Base circuit as control input terminal circuit 50A Gate circuit as control input terminal circuit C Control device of the present invention

Claims (8)

(57) [Claims] 1. A switching element which performs on / off control by applying a positive voltage and a negative voltage to a control input terminal, comprising: a DC power supply connected in series to the switching element; and a DC power supply when the switching element is turned off. A positive voltage source capacitor and a control capacitor connected in series to each other, and a negative current charged by a discharge current of the control capacitor discharged through the switching element when the switching element is turned on.
Characterized by comprising a capacitor for pressure source and a positive electrode voltage and the control input circuits for controlling the control input of the switching element using a negative electrode voltage of the negative voltage source capacitor of the positive voltage supply capacitor A switching device control device. 2. A diode interposed between a positive electrode charging terminal of the positive voltage source capacitor and a positive electrode terminal of the switching element, wherein the diode regulates discharge of the positive voltage source capacitor when the switching element is turned on. Item 2. A control device for a switching element according to Item 1. 3. The control device for a switching element according to claim 1, wherein said switching element is an NPN transistor. 4. The switching device control device according to claim 1, wherein said switching device is a MOS field effect transistor. 5. A bridge circuit formed by the switching element according to claim 1. 6. A speed control device for a servomotor using the bridge circuit according to claim 5. 7. An inverter device using the bridge circuit according to claim 4. 8. A switching regulator using the control device according to claim 1.