JPH01190268A - Transistor inverter - Google Patents

Abstract

PURPOSE:To save electric power, by adding a comparator, a second transistor and a detection diode. CONSTITUTION:A transistor inverter is composed of a rectification section 1, a main circuit transistor(Tr) 2 and a reverse-parallel diode 3, a waveform generation section 4, a photocoupler 5, the 1st Tr 7, a comparator 9, a detection diode 10, the 2nd-4th Tr 11-13, a diode group 16, etc., and it drives a motor 18. When the current flows through this main circuit Tr 2, the 2nd Tr 11 turns OFF as the output of the comparator 9 gets to an 'L' level, so that the current is supplied to the base of the Tr 2 and it works. On the other hand, when the current flows through reverse-parallel diode 3 (when the Tr 2 need not work), the output of the comparator 9 gets to an 'H' level; the 2nd Tr 11 turns 'ON' and works so as not to supply the current to the base of the Tr 2.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a transistor inverter that arbitrarily changes the rotational speed of an electric motor.

BACKGROUND TECHNOLOGY Generally, transistor inverter devices are provided with a transistor base drive circuit in order to control the main circuit transistors, as shown in Japanese Patent Application Laid-open No. 82-138069, but in particular, in large capacity transistor inverter devices, However, the problem is that the power consumption of the base drive circuit increases and the heat generated by the circuit components increases. In the figure, 21 is a DC power supply, 22 is a transistor bridge forming an inverter circuit, 23 is a load, and a current detector 24 for detecting a load current is provided on the output side of the inverter circuit.

Further, the output of the current detector 24 is introduced into a current detection circuit 26, and the output signal of this current detection circuit 26 is further passed through a current direction discriminator 27 to a base signal distribution circuit (one phase).
8. On the other hand, the output signal of the inverter control circuit 25 is also introduced into this base signal distribution circuit 28, but this circuit 28 has a timer 29. This imposes an AND condition on the transistor drive signal from 25 and the current direction signal from current direction determination 27.

The operation of the conventional example having the above configuration is as follows.

The current detector 24 detects the load current, guides it to the polarity discriminator 27 to detect the current direction, and uses the AND condition of this current direction signal and the transistor drive signal given from the control circuit 26 to drive the transistor. Ru. Thereby, as shown in FIG. 3, supply of base current during unnecessary periods can be eliminated. That is, the current direction signal is 1
! 1111 means that the transistor T1 or the diode D4 is conductive, and it is meaningless to supply the base current to the transistor T4, and only when the current direction signal is "○"'. The transistor was driven according to the signal.

Problems to be Solved by the Invention However, the conventional configuration requires a large number of circuits and components such as a current detection circuit, a current direction discriminator base signal distribution circuit, and a timer, resulting in an increase in cost.

SUMMARY OF THE INVENTION In order to solve the above problems, it is an object of the present invention to provide a base drive circuit that uses fewer components and can save power.

Means for Solving the Problems In order to achieve the above problems, the present invention comprises: a main circuit transistor bridge-connected to the output of a rectifier; an anti-parallel diode connected anti-parallel to the main circuit transistor;
a comparator whose reference input is connected to the emitter of the main circuit transistor; a detection diode whose anode is connected to the signal input of the comparator; a detection diode whose cathode is connected to the collector of the main circuit transistor; and the output of the comparator and the base thereof. A second transistor (NPN) connected to the base, a third transistor (NPN) connected to the base of the collector of the second transistor and the collector of the first transistor, and the emitter and emitter of the third transistor, In addition, a fourth transistor (PNP) whose base is connected to the base
and a second transistor connected to the collector of the third transistor.
The configuration has a resistance of .

Effect of the present invention Due to the above-mentioned configuration, when current flows through the main circuit transistor, the output of the comparator becomes 11 L I+
When the level is reached, the second transistor becomes a FF, and current is supplied to the base of the main circuit transistor.
The main circuit transistor operates, but when current flows through the anti-parallel diode, that is, when the main circuit transistor does not need to operate, the output of the comparator becomes "H" level and the second transistor is "ON". However, it operates in such a way that no current is supplied to the base of the main circuit transistor.

Embodiment FIG. 1 is an electric circuit diagram showing an embodiment of the present invention, in which 1 is a rectifier for rectifying and smoothing the power supply, 2 is a main circuit connected to the output of the rectifier 1 in a bridge, and transistor 3 is connected to this main circuit. an anti-parallel diode connected in anti-parallel with transistor 2;
4 is a waveform generator that outputs an arbitrary frequency waveform. 6
6 is a photocoupler that receives the output signal of the waveform generator, and 6 is a phototransistor within the photocoupler 5. 7
is a first transistor (NPN) that operates in reverse phase with this phototransistor 6, 8 is a first resistor connected to the collector of this first transistor 7, and 9 is a reference input (9-
a) is a comparator connected to the emitter of the main circuit transistor 2. 10 is the signal input of the ratio 11iZ unit 9 (
9-b) and a sensing diode whose anode is connected to the collector of the main circuit transistor 2, and whose forward voltage is smaller than that of the anti-parallel diode 3. 11
is a second transistor (NPN) whose base is connected to the output (a-c) of the comparator 9; 12 is the collector of this second transistor 11 and the first transistor 7;
A third transistor (N
PN), 13 is a fourth transistor (PNP) in which the emitter of the third transistor 12 is connected to the emitter, and 14 is a second resistor connected to the collector of the third transistor. 15 is a third resistor connected to the anode of the detection diode 1°; 16 is a diode group whose anode is connected to the emitter of the main circuit transistor; 17 is a fourth resistor connected to the anode of the diode group 16; A motor is connected to the output of the main circuit transistor 2.

Next, the operation of the transistor inverter configured as described above will be explained. First, when the power is turned on, the rectifier 1 converts it into a direct current, and a voltage is applied to the main circuit transistor 2 and the anti-parallel diode 3. On the other hand, the waveform generating section 4 generates a PWM waveform of an arbitrary frequency, communicates with the photocoupler 6, and turns the internal phototransistor into ○N/○FF. This○
N/○FFN/upper first transistor 7 that operates in reverse phase
can lead to That is, when the phototransistor is ON, the first transistor 7 is OFF, current flows through the first resistor 8, and current flows into the base of the third transistor 12, so the third transistor 12 is ONL. , the current flows into the base of the main circuit transistor 2 through the second resistor 14, and the main circuit transistor 2 is turned ON.
However, since a voltage is applied to this main circuit transistor 2, a current flows to the motor 18.

On the other hand, when the phototransistor is OFF, the first transistor 7 is ON, and in order to draw out the base current of the fourth transistor 13, the base current of the main circuit transistor 2 rapidly increases due to the reverse voltage created by the diode group 16. The main circuit transistor 2 is turned off. In other words, the main circuit transistor 2 operates in the same mode as the phototransistor 6.

Next, considering the output load, it is an electric motor, so-called L
Since it is a load, there is a period in which current flows through the anti-parallel diode 3 due to the action of back electromotive force.

Conventionally, current flowed through the base of the main circuit transistor 2 even during this period, but the present invention cuts the base current during this period by the operation shown below. First, no current flows through the anti-parallel diode 3. In other words, when the main circuit transistor 2 needs to be 0N10FF (called the transistor region), and when current flows through the anti-parallel diode 3, that is, when the main circuit transistor 2 does not need to be 0N10FF (called the diode region) ) operation will be explained.

Now, the signal input value is vIN, and the reference input value is vREF.

The emitter-collector voltage of main circuit transistor 2 is vc
E. When the forward voltage of the detection diode 1o is vDl and the forward voltage of the anti-parallel diode 3 is tossed with ■D2, in the transistor region, ■work h:vREF+(vCE+vD1), and vcE+vD1 on the right side is a positive number. Therefore, vIN on the left side is vR
Greater than EF. In this case, the output of comparator 9 (9-
c') outputs "L'" level and the second transistor 11 is turned off, so the third transistor 12 and the fourth transistor 13 operate in the same way as the phototransistor 6, so the main circuit transistor 2 is 0N10F
F works.

Next, considering the diode area, vIN:vREF+(vDl-■D2), vDl-vD2 on the right side is a negative number, and vIN on the left side is vREF.
become smaller. Therefore, the output of comparator 9 (9-c)
becomes “H” level, and the second transistor 11 becomes O
Therefore, the base current of the third transistor 12 is no longer supplied. Therefore, the main circuit transistor 2
N10FF does not work.

According to the configuration of the above embodiment, by simply adding the comparator 9, the second transistor 11, and the detection diode 10, it is possible to cut the base current to the main circuit transistor 2 when current flows through the antiparallel diode 3. , the power consumption of the inverter base drive circuit can be reduced.

In addition to the effects of the invention, as is clear from the examples, the present invention includes a rectifier that rectifies and smoothes a power supply, a main circuit transistor connected in parallel to the output of this rectifier, and a main circuit transistor connected in inverse parallel to this main circuit transistor. an antiparallel diode connected to the diodes, a waveform generator that outputs an arbitrary frequency waveform, a photocoupler that receives the output signal of the waveform generator, and a first transistor (NPN) that operates in opposite phase to the phototransistor of the photocoupler. and a first transistor connected to the collector of this first transistor.
a comparator whose reference input is connected to the emitter of the main circuit transistor, an anode connected to the signal input of the comparator, a cathode connected to the collector of the main circuit transistor, and a forward voltage is connected to the anti-parallel diode. a second transistor (NPN) having its base connected to the output of said comparator; a second transistor (NPN) having its base connected to the collector of said first transistor; transistor (NP
N), and a fourth transistor (PNP) in which the emitter of the third transistor is connected to the base of the transistor,
Since it is equipped with a second resistor connected to the collector of the third transistor, it is possible to obtain the desired effect without adding a large number of parts as in the conventional case, that is, with a small increase in cost. Therefore, it contributes to improving product value.

[Brief explanation of the drawing]

FIG. 3 is an electrical circuit diagram of the system inverter, and is an explanatory diagram of the operation of FIG. 2. DESCRIPTION OF SYMBOLS 1... Rectifying section, 2... Main circuit transistor, 3... Anti-parallel diode, 4... Curved waveform generating section, 5... Photocoupler, 7... ...First
transistor, 8...first resistor, 9...mountain...
Comparator, 1o...Detection diode, 11...Mountain, second transistor 12...Third transistor, 13...Fourth transistor, 14...
...Second resistance. Name of agent: Patent attorney Toshio Nakao and 1 other person/-
---I-ga? -Main mouth g7-Rareshienuku

Claims (1)

[Claims] A rectifier that rectifies and smoothes the power supply, a main circuit transistor bridge-connected to the output of this rectifier, an anti-parallel diode connected in anti-parallel to this main circuit transistor, and a waveform generator that outputs an arbitrary frequency waveform. a photocoupler that receives the output signal of the waveform generator, a first transistor that operates in opposite phase to the phototransistor of the photocoupler, and a first transistor that is connected to the collector of the first transistor.
a comparator whose reference input is connected to the emitter of the main circuit transistor, an anode connected to the signal input of the comparator, a cathode connected to the collector of the main circuit transistor, and a forward voltage is connected to the anti-parallel diode. a second transistor having its base connected to the output of said comparator; and a third transistor having its base connected to the collector of said second transistor and the collector of said first transistor; A transistor inverter comprising: a fourth transistor having a polarity opposite to that of each of the transistors in which the emitters of the third transistor are connected together and the bases thereof are connected; and a second resistor which is connected to the collector of the third transistor. .