KR19980057569A - Switching driving device of inverter in electric vehicle - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switching driving device of an inverter in an electric motor. A power circuit 10 for converting DC power into AC power; A control circuit 20 for outputting first and second control signals S1 and S2; And a switching driving circuit 30 which receives the first and second control signals S1 and S2 and outputs the first and second switching drive signals S1 'and S2', wherein the switching is performed. First and second push-pull in which the driving circuit 30 receives the first and second control signals S1 and S2 from the control circuit 20 through the base of the first and second buffers 31 and 32. Amplifiers 33 and 34; First and second light emitting devices 35 having an anode terminal connected to an output terminal of the first and second push pull amplifiers 33 and 34 and a cathode terminal connected to an output terminal of the second and first push pull amplifiers 34 and 33. , 36); First and second light receiving elements 37 and 38 that receive optical signals output from the first and second light emitting elements 35 and 36 and convert them into electric signals; First and second driving units 39 for supplying first and second switching driving signals S1 ′ and S2 ′ to the power circuit 10 according to electrical signals input from the first and second light receiving elements 37 and 38. And 40, which prevents the first and second light emitting elements 35 and 36 from emitting light at the same time by using the directionality of the light emitting elements, thereby providing two switching elements 1 and 2 in the arm 11. Is prevented from being turned on at the same time to prevent breakage of the switching element due to a short circuit.

Description

An apparatus for driving a switch of inverter in a electric-train

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter of an electric vehicle that performs pulse width modulation (PWM) using a switching element, and more particularly, to an electric vehicle designed to prevent two switching elements existing in one arm from being switched on at the same time. The present invention relates to a switching drive device of an inverter.

In general, an inverter refers to a device for converting a DC line voltage applied through a pantograph into a predetermined AC power suitable for driving an induction motor. The predetermined DC power input to the inverter is converted into a three-phase AC power. An induction motor is input to drive the induction motor.

That is, the inverter controls the speed of the induction motor by controlling the voltage to increase or decrease the rotational force of the induction motor and control the frequency to increase or decrease the rotational speed of the induction motor.

FIG. 1 is a circuit diagram showing a general inverter, and as shown in FIG. 1, an inverter includes a power circuit 10, a control circuit 20, and a switching driving circuit 30.

The power circuit 10 is composed of three arms 11, 11 ′ and 11, each arm 11 having two switching elements connected in series, that is, the first switching element 1 and the second. It is comprised by the switching element 2, Each switching element is switched on / off by the control signal output from the said control circuit 20, and it converts and outputs the input DC power supply into AC power supply.

In this case, in order to transmit the control signals (S 1,2,3,4,5,6) from the control circuit 20 to the power circuit 10 generally requires electrical insulation, that is, the control circuit 20 In general, since the power circuit 10 uses a voltage of about 1500 V, the ground of the control circuit 20 and the power circuit 10 needs to be separated.

To this end, the inverter generally includes a switching driving circuit 30 implemented with an optical fiber and a photo coupler.

Referring to the operation of the switching driving circuit 30 in more detail, for example, when the high level first control signal S1 is output from the control circuit 20, the high level first control signal S1 is generated. The first buffer BUF1 is input to the first buffer BUF1 and outputs a low level signal. Accordingly, the Vcc1 (5V) voltage is applied to the anode terminal of the first photodiode D1 and the low level signal (0V) voltage is applied to the cathode terminal, so that a current is caused by the voltage difference between both ends of the first photodiode D1. And the first photodiode D1 emits light. The first phototransistor T1 receives the light and is turned on so that a predetermined voltage Vcc2 is applied to the collector terminal of the first phototransistor T1 and bypassed to the ground through the emitter terminal. Accordingly, the low level signal 0V is input to the first driver A connected in parallel to the collector terminal of the first photo transistor PT.

On the contrary, when the low level first control signal S1 is output from the control circuit 20, the low level first control signal S1 is input to the first buffer BUF1, and the first buffer ( BUF1) outputs a high level signal. Accordingly, the voltage of Vcc1 (5V) is applied to the anode terminal of the first photodiode D1 and the voltage of the high level signal (5V) is applied to the cathode terminal. ) And no current is generated. As no current flows in the first photodiode D1, the first phototransistor T1 is turned off, and a high level signal Vcc2 is input to the first driver A. FIG.

Accordingly, the first driver A switches the first switch of the first arm 11 of the power circuit 10 according to a high or low level signal input from the collector terminal of the first photo transistor T1. The first switching driving signal S1 ′ having a high or low level is output to the element 1, and the switching driving signal S1 ′ is input to a base end of the first switching element 1 to provide the first switching element. The switching element 1 is switched on / off.

At this time, the six switching elements (two switching elements are provided in each of the three arms) present in the power circuit 10 are all six control signals S 1, which are output from the control circuit 20. 2,3,4,5,6).

At this time, when two switching elements 1 and 2 in the arm 11 are turned on at the same time, a short circuit occurs, which is called a dark short.

When the dark short circuit occurs, a current of more than a capacity flows instantaneously, and an expensive switching element frequently occurs due to the overcurrent.

That is, in the conventional inverter, when two photo couplers D1-T1 and D2-T2 for driving two switching elements 1 and 2 in one arm 11 emit light at the same time due to electrical noise, There was a problem that a paragraph could be imported. In particular, as the central control device becomes higher and higher, and the switching speed of the switching device increases, malfunctions due to electrical noise become more frequent.

Accordingly, the present invention has been made to solve the above problems, to provide a switching drive device of the inverter in the motor which is to prevent the switching of the two switching elements (1, 2) in one arm 11 at the same time. Its purpose is to.

In the motor according to the present invention for achieving the above object, the switching driving apparatus of the inverter is composed of three arms, and each arm is composed of a first switching element and a second switching element. A power circuit configured to switch on / off the first switching element and the second switching element by a first switching driving signal and a second switching driving signal to convert the input DC power into an AC power; A control circuit outputting a first control signal and a second control signal to turn on / off the first switching element and the second switching element; And a switching driving circuit receiving a first control signal and a first control signal from the controller and outputting a first switching driving signal and a second switching driving signal to the power circuit. A first buffer unit for buffering a first control signal input from the control circuit; A second buffer unit for buffering a second control signal input from the control circuit; A first push-pull amplifier on which a base end receives the buffered first control signal; A second push-pull amplifier, the base of which receives the buffered second control signal; A first light emitting element having an anode end connected to an output end of the first push-pull amplifier and a cathode end connected to an output end of a second push-pull amplifier; A second light emitting element having an anode end connected to the output end of the second push-pull amplifier and a cathode end connected to the output end of the first push-pull amplifier; A first light receiving element which receives an optical signal output from the first light emitting element and converts the light signal into an electrical signal; A second light receiving element which receives an optical signal output from the second light emitting element and converts the light signal into an electrical signal; A first driver supplying a first switching driving signal to the power circuit according to an electrical signal input from the first light receiving element; And a second driver supplying a second switching driving signal to the power circuit according to the electrical signal input from the second light receiving element.

That is, the apparatus of the present invention connects the first and second light emitting elements in parallel between the output terminals of the first and second push-pull amplifiers in the reverse direction, so that the directionality of the light emitting elements (only emits light when voltage is applied to one side). By using the above, the first and second light emitting devices are prevented from simultaneously emitting light, thereby preventing two switching devices existing in one arm from being switched on at the same time, thereby preventing breakage of the switching device due to a short circuit.

1 is a circuit diagram showing a general inverter circuit,

2 is a circuit diagram showing a switching driving device of an inverter in an electric vehicle according to the present invention;

3A is a view showing the direction of current flow when the first photodiode emits light;

3B is a view showing the direction of current flow when the second photodiode emits light.

* Names of symbols for main parts of the drawings

10: power circuit 20: control circuit

30: switching drive circuit 11: first arm

1: first switching means 2: second switching means

31: first buffer 32: second buffer

33: first push-pull amplifier 34: second push-pull amplifier

35 first light emitting element 36 second light emitting element

37: First light receiving element 38: Second light receiving element 38

39: first driver 40: second driver

D: Reverse current blocking diode R1, R3: Current limiting resistor

Q1, Q2, Q3, Q4: Transistor

R2-C1, R4-C2: Speed Up Resistors and Capacitors

Hereinafter, the operation and effects of the apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

2 is a circuit diagram showing a switching driving device of an inverter in an electric vehicle according to the present invention.

As shown in FIG. 2, the apparatus of the present invention is composed of three arms, and each of the arms 11 is composed of a first switching element 1 and a second switching element 2. The first switching element 1 and the second switching element 2 are switched on / off by the first switching driving signal S1 'and the second switching driving signal S2', respectively, to exchange the input DC power. A power circuit 10 for converting and outputting to a power source; A control circuit (20) for outputting a first control signal (S1) and a second control signal (S2) to turn on / off the first switching element (1) and the second switching element (2); And a first switching signal S1 ′ and a second switching driving signal S2 ′ received from the control unit 20 by receiving a first control signal S1 and a first control signal S2. In the inverter of the electric vehicle provided with a switching drive circuit 30 for outputting, the switching drive circuit 30, the first to invert the first control signal (S1) input from the control circuit 20 A buffer section 31; A second buffer unit 32 for inverting and outputting the second control signal S2 input from the control circuit 20; A first push-pull amplifier (33) whose base end receives the inverted first control signal (S1); A second push-pull amplifier (34) on which a base end receives the inverted second control signal (S2); A first photodiode 35 having an anode end connected to the output end of the first push-pull amplifier 33 and a cathode end connected to the output end of the second push-pull amplifier 34; A second photodiode 36 having an anode end coupled to the output end of the second push-pull amplifier 34 and a cathode end connected to the output end of the first push-pull amplifier 33; A first photo transistor 37 which receives an optical signal output from the first photo diode 35 and converts the optical signal into an electrical signal; A second photo transistor 38 which receives an optical signal output from the second photo diode 36 and converts it into an electrical signal; A first driver 39 supplying a first switching driving signal S1 'to the power circuit 10 according to an electrical signal input from the first photo transistor 37; And a second driver 40 supplying the second switching driving signal S2 ′ to the power circuit 10 according to the electrical signal input from the second photo transistor 38.

In addition, the apparatus of the present invention includes: a first reverse voltage blocking diode (D1) connected in parallel with the first photodiode 35 in a reverse direction to protect the first photodiode 35 from reverse voltage; The second photodiode 36 is connected in parallel in a reverse direction, and further includes a second reverse voltage blocking diode D2 that protects the second photodiode 36 from reverse voltage.

In addition, the apparatus of the present invention is connected between the output terminal of the first push-pull amplifier 33 and the first photodiode 35, so as to quickly switch on / off the first photodiode 35. 1 speed-up part R2, C1; Second speed-up parts R4 and C2 connected between the output terminal of the second push-pull amplifier 34 and the second photodiode 36 to quickly switch on / off the second photodiode 36. It is configured to further include.

Subsequently, when the first photodiode 35 emits light, when the second photodiode 36 emits light, and the first and second photodiodes 35, 36) will be described below in case of not emitting light at the same time.

3A shows the direction of current flow when the first photodiode 35 emits light, and FIG. 3B shows the direction of current flow when the second photodiode 36 emits light.

1. When the first photodiode emits light

When the control circuit 20 outputs the low level first control signal S1 and the high level second control signal S2, the low level first control signal S1 is output to the first buffer 31. Inverted output.

Accordingly, the high level signal output from the first buffer 31 is input to the base terminal of the first push-pull amplifier 33, whereby the first transistor Q1 is turned on and the second transistor Q2 is turned on. Is off.

On the other hand, the high level second control signal S2 output from the control circuit 20 is input to the second buffer 32 is inverted and output.

Accordingly, the low level signal output from the second buffer 32 is input to the base terminal of the second push-pull amplifier 34, whereby the fourth transistor Q4 is turned on and the third transistor Q3 is turned on. Is off.

Accordingly, as shown in FIG. 3A, a predetermined voltage Vcc1 is applied to the collector terminal and the emitter terminal of the first transistor Q1 to provide a predetermined current ( ) Is applied to the emitter terminal and the collector terminal of the fourth transistor Q4 through the first photodiode 35 and flows to the ground.

As the current flows through the first photodiode 35, the first photodiode 35 emits light. As a result, the first phototransistor 37 is turned on so that a predetermined voltage Vcc3 is applied to the first photodiode 35. It is applied to the collector stage of transistor 37 and bypassed to ground through the emitter stage.

Accordingly, the low level signal 0V is input to the first driver 39 connected in parallel to the collector terminal of the first photo transistor 37.

The first driver 39 may be configured as a first switching element 1 of the first arm 11 of the power circuit 10 according to a high or low level signal input from the collector terminal of the first photo transistor 37. ) To output a high or low level first switching driving signal S1 ′, and the first switching driving signal S1 ′ is input to a base end of the first switching element 1 to switch the first switching. Switch device 1 on and off.

2. When the second photodiode emits light

When the control circuit 20 outputs the high level first control signal S1 and the low level second control signal S2, the high level first control signal S1 is output to the first buffer 31. Inverted output.

Accordingly, the low level signal output from the first buffer 31 is input to the base terminal of the first push-pull amplifier 33, whereby the second transistor Q2 is turned on and the first transistor Q1 is turned on. Is off.

On the other hand, the low level second control signal S2 output from the control circuit 20 is input to the second buffer 32 is inverted and output.

Accordingly, the high level signal output from the second buffer 32 is input to the base terminal of the second push-pull amplifier 34, and accordingly, the third transistor Q3 is turned on and the fourth transistor Q4 is turned on. Is off.

Accordingly, as shown in FIG. 3B, a predetermined voltage Vcc2 is applied to the collector terminal and the emitter terminal of the third transistor Q3 to provide a predetermined current ( ) Is applied to the emitter terminal and the collector terminal of the third transistor Q3 through the second photodiode 36 and flows to the ground.

As the current flows through the second photodiode 36, the second photodiode 36 emits light. As a result, the second phototransistor 38 is turned on so that a predetermined voltage Vcc4 is applied to the second photodiode 36. It is applied to the collector stage of transistor 38 and bypassed to the ground through the emitter stage.

Therefore, the low level signal 0V is input to the second driver 40 connected in parallel to the collector terminal of the second photo transistor 38.

The second driving unit 40 is the second switching element 2 of the first arm 11 of the power circuit 10 in response to a high or low level signal input from the collector terminal of the second photo transistor 39. ) And outputs a second switching driving signal S2 'having a high or low level, and the second switching driving signal S2' is input to a base end of the second switching element 2 so as to output the second switching driving signal S2 '. Switch on / off device 2.

3. When the first and second photodiodes do not emit light at the same time

The control circuit 20 outputs a high level first control signal S1 and a high level second control signal S2, or a low level first control signal S1 and a low level second control. When the signal S2 is output, the first and second photodiodes 35 and 36 do not emit light at the same time.

For example, when the control circuit 20 outputs the high level first control signal S1 and the high level second control signal S2, the high level first control signal S1 is the first buffer 31. Inverted output.

Accordingly, the low level signal output from the first buffer 31 is input to the base terminal of the first push-pull amplifier 33, whereby the second transistor Q2 is turned on and the first transistor Q1 is turned on. Is off.

On the other hand, the high level second control signal S2 output from the control circuit 20 is input to the second buffer 32 is inverted and output.

Accordingly, the low level signal output from the second buffer 32 is input to the base terminal of the second push-pull amplifier 34, whereby the fourth transistor Q4 is turned on and the third transistor Q3 is turned on. Is off.

Accordingly, since no current flows in the first and second photodiodes 35 and 36, the first and second photodiodes 35 and 36 do not emit light, and thus the first and second phototransistors 37 38 is turned off, and high level signals Vcc3 and Vcc4 are input to the first and second driving units 39 and 40.

The first and second driving units 39 and 40 may include the first arm 11 of the power circuit 10 according to a high or low level signal input from the collector terminals of the first and second photo transistors 37 and 38. The first and second switching driving signals S1 'and S2' having high or low levels are outputted to the first and second switching elements 1 and 2 of the second, second and second switching driving signals S1 ', S2 ') is input to the base end of the first and second switching elements 1 and 2 to switch on / off the first and second switching elements 1 and 2.

At this time, the six switching elements (two switching elements are provided in each of the three arms) present in the power circuit 10 are all six control signals S 1, which are output from the control circuit 20. 2,3,4,5,6).

Here, the diodes D1 and D2 are reverse voltage blocking diodes for protecting the first and second photo transistors 35 and 36 from reverse voltage, and the resistors R1 and R3 are current limiting resistors. (C1, C2) and resistors R3, R4 are speed-up capacitors and resistors for quickly performing switching on / off of the first and second photodiodes 35,36.

As described above, the apparatus of the present invention connects the first and second light emitting elements 35 and 36 in parallel between the output terminals of the first and second push-pull amplifiers 33 and 34 in reverse directions, thereby providing directivity of the light emitting elements. Using the characteristic of emitting light only when a voltage is applied to only one side, by preventing the first and second light emitting elements 35 and 36 from emitting light at the same time, The effect is that the two switching elements 1 and 2 are prevented from being switched on at the same time to prevent breakage of the switching element due to a dark short.

Claims (3)

It consists of three arms, and each said arm 11 is comprised from the 1st switching element 1 and the 2nd switching element 2, The 1st switching drive signal S1 'and the 2nd switching drive A power circuit 10 for switching the first switching element 1 and the second switching element 2 on and off by a signal S2 'and converting and outputting the input DC power to AC power; A control circuit (20) for outputting a first control signal (S1) and a second control signal (S2) to turn on / off the first switching element (1) and the second switching element (2); And a first switching signal S1 ′ and a second switching driving signal S2 ′ received from the control unit 20 by receiving a first control signal S1 and a first control signal S2. In the inverter of the electric vehicle provided with a switching drive circuit 30 for outputting The switching drive circuit 30, A first buffer part 31 for buffering the first control signal S1 input from the control circuit 20; A second buffer unit 32 for buffering the second control signal S2 input from the control circuit 20; A first push-pull amplifier (33) on which a base end receives the buffered first control signal (S1); A second push-pull amplifier (34) on which a base end receives the buffered second control signal (S2); A first light emitting element 35 having an anode end connected to the output end of the first push-pull amplifier 33 and a cathode end connected to the output end of the second push-pull amplifier 34; A second light emitting element 36 having an anode end connected to the output end of the second push pull amplifier 34 and a cathode end connected to the output end of the first push pull amplifier 33; A first light receiving element 37 which receives an optical signal output from the first light emitting element 35 and converts it into an electrical signal; A second light receiving element 38 which receives an optical signal output from the second light emitting element 36 and converts the light signal into an electrical signal; A first driver 39 supplying a first switching driving signal S1 'to the power circuit 10 according to an electrical signal input from the first light receiving element 37; And And a second driver 40 for supplying a second switching drive signal S2 'to the power circuit 10 in accordance with an electrical signal input from the second light receiving element 38. In the switching of the driving device. The method of claim 1, A first reverse voltage blocking diode D1 connected in parallel with the first light emitting element 35 to protect the first light emitting element 35 from a reverse voltage; And a second reverse voltage blocking diode D2 which is connected in parallel with the second light emitting element 36 in a reverse direction and protects the second light emitting element 36 from reverse voltage. Switching drive device of inverter in electric motor. The method of claim 1, First speed-up parts R2 and C1 connected between an output terminal of the first push-pull amplifier 33 and the first light emitting device 35 to quickly switch on / off the first light emitting device 35. Wow ; Second speed-up parts R4 and C2 connected between the output terminal of the second push-pull amplifier 34 and the second light emitting element 36 to quickly switch on / off the second light emitting element 36. Switching drive device of the inverter in the motor, characterized in that it further comprises.