JPS59208937A - Drive controller of semiconductor switch element - Google Patents

Abstract

PURPOSE:To ensure the stable drive of a semiconductor switch element without increasing the power loss of a resistance by short-circuiting a part of a series resistance when the charging voltage is less than a prescribed level. CONSTITUTION:When the voltage of a DC power supply 1 has a drop, the voltage of a capacitor C1 is also reduced less than the Zener voltage of a Zener diode DZIA. As a result, the non-inverted input voltage of a comparator 6 is reduced less than the inverted input. Therefore the output of the comparator 6 is set at level ''O'', and a current flows to a photodiode PD3. Thus a phototransistor PT3 is turned on. Then only an R5 has the charging resistance of the C1, and therefore the charging current increases. Thus the voltage of the C1 can be increased. In other words, a switch circuit using the PT3 is acutuated in response to the voltage of the C1 to switch the charging resistance. Thus a satisfactory charging resistance is always obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention d relates to a drive control device for a half-disassembled switch element such as an impark or a chopper.

[Technical background of the invention and its problems]

Figure 1 shows a conventional AC wiping motion composed of semiconductor switch elements! ? The inverter for driving Ui is shown.

In Figure 1, the VC between the positive and negative bus lines PN of the box flow Amogen 1
Null semiconductor switch elements MU, M, V, MW from MO8F, tl'I'' connected to the iθ-column, respectively
, MX, MY.

It is composed of MZ. Although a giant transistor (GTR) may be used as the half-disassembled switch element, a case where an MO8FET is used will be described below. M.O.
At each terminal of SFET, G is the gate, D is the drain,
S is the source.

Each MO8FET has a snubber circuit D-
8 and G-8 (((is the overvoltage prevention Zener diode DZ, ~DZ6 and the resistor RG, ~I
(G, is connected.

It is a Qn buffer capacitor. 2 is an AC motor such as an induction motor or a synchronous electric TJJJ machine.

FIG. 2 shows a drive circuit for each MO8FET. Components that are the same as those in FIG. 1 are given the same symbols.

Since the potentials of the MO8FE'l'' constituting the inverter and the control circuit are generally not equal, the control circuit cannot directly drive each MO8FET.
Generally, a system is used in which an independent drive power supply 3 having the same potential as the 19FET is provided, and signals from the control circuit are isolated by a photocassette PC, 2, or the like. The control circuit is well known and is not specifically illustrated. Note that MX, M'
It is also possible to use a common driving power source for Y, tA, and Z. '1. F' and OF are the filter resistance and filter capacitor of the MU drive turtle source 3.

Next, easily turn on and off the 840S PETMU ff+
ll f+M] will be explained. A current is caused to flow through the photodiode PD of the photocoupler PC by the control signal from the control device (not shown).Then, the phototransistor PT of the photocoupler PC is turned on, and the output of the photocoupler PC becomes the level "OI". 5. The output of the NOT circuit 4 is at the level tt, p. 9. The input current 8711 is passed through the limiting resistor 几2, and the voltage is supplied to the MO8FETr, vu gate)U◇. In this case, the input current is MOS L' ID
T's input current flows only for a short time, and after that, almost no current flows. MO8FEi'
VC illusion to turn off IVU, photocoupler PC3, ○ photodiode PD, yc connection '-5 style... r hoo... When the current of the photodiode PD1 of the photocoupler PC becomes 1, the output of the phototransistor PT goes to the level "LL", and the output of the NOT circuit 4 goes to the level "0".
', and the 408 FET turns off.

In this case, the current flowing through the NOT circuit only flows for a short time when the charge in the input capacitance of the MO8FET is discharged, and after that, almost no current flows. In other words, only a very small amount of current flows on average as the gate current of the MOSFET.

However, even if a power supply with a small capacity is used, the power supply must be isolated from the control circuit, making it complicated.
Becomes expensive.

This is a circuit that obtains the MU I drive power using the i4 diode capacitor C1. Similarly, the MX 1 drive power source is made from a resistor R0, a Zener diode DZ2A capacitor C2.

Next, the principle of operation will be explained with reference to FIG.

Traps that are the same as those in Figures 1 and 2 are given the same symbols.

For simplicity, a series circuit of MU and MX will be described. Incidentally, the series circuits of MV and MY, MW and MZ also perform exactly the same operation.

Generally, when operated as an inverter, MOSFE
When 40 to T is on, MX is off, and when MU is off, MX is on. If we consider that MU is off and 1,4X is on, the positive side P of DC power supply 1 → resistor 1
Current flows through the path of Mo, → diode 1), → capacitor C8 → MX, and charge is accumulated in capacitor C1. At this time, since the capacitor CHVC is connected in parallel with the Zener diode D21, it is clamped to the voltage tj of the capacitor C7: Zener diode DZIA no Zener: specific pressure. The pressure applied to the capacitor C7 is used as a driving source for the MU. Note that the diode J]5 is used to prevent the capacitor CI from being discharged when the MU is turned on. Also, resistor 1 is also set to 7: Aμ when moving 4. Ij, MX: Both are redundant resistors that are used to charge the capacitor CI unevenly when the capacitor CI is off. M

However, 1 using a huge current power supply IK battery or solar battery
Considering the convenience, when a battery is used, the DC voltage varies greatly depending on the state of charge.

'Furthermore, when solar cells are used, the direct current pressure varies greatly depending on the sunlight conditions. If the DC voltage becomes lower, the VC that guarantees the voltage of capacitors a, , a2 must reduce the value of the resistor R, , R, . However, if the resistor R, 5, R, is made smaller, the DC voltage increases. If this happens, there is a problem that the power loss of the resistors IL, ., ., increases.

[Purpose of the invention]

The purpose of the present invention was made in view of the above-mentioned problem of VC, and when obtaining a driving power source for a semiconductor switching element from a power source whose voltage fluctuates greatly, it is possible to stably and reliably obtain the driving power of a semiconductor switching element from a power source whose voltage fluctuates greatly. An object of the present invention is to obtain a drive-side device for a semiconductor switch element capable of driving the semiconductor switch element.

[Summary of the invention]

The present invention applies voltage to a capacitor through a series resistor,
In a device that uses the charging voltage of this capacitor as a driving power source for a semiconductor switching element, there is provided a comparator that obtains a voltage drop detection signal when the charging voltage is below a predetermined value, and a comparator that obtains a voltage drop detection signal when the charging voltage is below a predetermined value. A drive control device for a semiconductor switch element is provided with a switch circuit that short-circuits a part of the series resistor to reduce power loss of the series resistor.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG. Components that are the same as those in FIG. 3 are denoted by the same reference numerals, and explanations thereof will be omitted. Comparing with Fig. 3, the resistance I(,8,R,,R・10°RlH
, R+12, R13, Photocup-y PC! 3.
PC, Zener diode I) Z3A DZ4A
,, Polycomb resistor VTL+.

Add VB2, Conharataro, and 7.

Next, the operating principle will be explained. When the voltage of the DC power supply 1 is high, the voltage of the capacitor c1 is as high as the Zener voltage of the Zener diode DZIA.

Since the non-inverting input voltage of comparator 6 is proportional to the voltage of capacitor cI, when the voltage of capacitor C7 is high, the inverting input of conoparator 6 (Zener diode DZ
By adjusting the voltage to a higher voltage than the Zener voltage of 3A, the output of comparator 6 will be at level ``1''.
1d current does not flow through the photodiode P1)3 of the photocoupler PC. When no current flows through the photodiode PD3, the phototransistor PTs is turned off, and the charging current of the capacitor C8 also charges through the resistors rt, , i. In other words, when the DC' voltage is high, the charging resistance becomes small, so the resistance loss is small.

(a) When the voltage of the city power supply decreases, the voltage of the capacitor C1 also decreases below the Zener voltage of the Zener diode Dz+A. Since the non-inverting input voltage of the comparator 6 is set to be lower than the inverting input when the voltage of the capacitor C3 decreases, the output of the comparator 6 is at level '0''. Current flows through the photodiode PD3, and the phototransistor PT3 turns on.Phototransistor PT
When capacitor C1 is turned on, R5 is the only charging resistor of capacitor CI, so the charging current increases and the performance of capacitor C8 can be increased. That is, a switch circuit including a phototransistor PT3 is operated in accordance with the voltage of the capacitor C1 to switch the charging resistor so as to maintain a good charging resistor at a constant voltage of V.

〔Effect of the invention〕

According to the rv of the present invention, it is possible to provide a drive control device for a semiconductor switch element that obtains a stable drive power source without increasing the power loss of the resistor even if the drive power source for the semiconductor switch element is obtained from a power source whose voltage fluctuates greatly. .

[Brief explanation of drawings]

Figure 1 is an inverter main circuit diagram using MOSFET as a semiconductor switch element, Figure 2 is a MOSFET.
3 is a drive control circuit diagram of a MOSFET with a groove bottom so as to obtain drive power from the main circuit power supply, and FIG. 4 is a drive control circuit diagram of a semiconductor switch element according to an embodiment of the present invention. FIG. 3 is a circuit configuration diagram. ■...1M current power supply 2...AC' driving power source 3...Semiconductor switch element drive power supply 4.5...No'r circuit
6.7... Comparator PO4~P04... Photocoupler (73] 7) Proxy Masujishi Nori Chika 1g Yu (and 1 other person) Fig. 3 P MX system λU f9 No. 4 Fig. 4 MX No. 112 P Irisho

Claims (1)

[Claims] In a device in which a voltage is applied to a capacitor through a series resistor and the photoelectric voltage of this capacitor is used as a driving power source for a half-disassembled switch element, the voltage decreases when the charged Ti, 5iL pressure is 1 or more than the required value. 1. A drive control device for a semiconductor switching element, comprising: a comparator for obtaining a detection signal; and a switch circuit for shorting a part of the series resistor based on the voltage drop detection signal.