JPS5836176A - Transistor inverter - Google Patents

Abstract

PURPOSE:To perform a sinusoidal wave-triangular wave modulation system by controlling a DC voltage in response to the set frequency, counting via a ring counter and employing as a base signal of a transistor a data signal in an ROM. CONSTITUTION:A DC voltage is controlled via controllers 49, 32 peoportionally to a set frequency from a frequency setter 46, an ROM50 which stores a signal obtained via sinusoidal wave-triangular wave modulation and a ring counter 48 which counts in the set frequency are provided. The data signals which are stored in the addresses of the ROM corresponding to the counted values of the counter 48 are applied to the bases of transistors 35-36, 36-39, 37-40. In this manner, the waveform signals corresponding to the angle are stored in the ROM, thereby performing a sinusoidal wave-triangular wave modulation system with a simple circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sine wave-triangular wave modulation system, and relates to a transistor inverter device that combines PMM and sine wave PWM.

Generally, when driving a II conductive motor, if the power supply frequency is changed in order to change the rotational speed, the applied voltage must also be changed.

Therefore, conventionally, as shown in Figure 1, six transistors ill f21 (31 (41 (5) (6)),
Three sets of two connected in series are connected in parallel, and the output signal is obtained from the connection point of each series circuit at the base of each transistor fil --- +61 of the transistor inverter. A modulation signal is applied to control the on/off of each of these transistors (11--(6)), so that the applied voltage changes in accordance with the power frequency.And this sine wave-triangular wave modulation method is As shown in Figure 2, the voltage is set by the 1 frequency setter 0.

Phase % It is converted into a three-phase sine wave of S phase and T phase, which have different phases by 120 degrees from each other. Further, the pulse train signal r) is input to a triangular wave generator α and is converted into a triangular wave (SW). On the other hand, the voltage (?,) is
A signal (vo) is output corresponding to the output voltage (af)K of the inverter shown in the figure.

This signal (vo) is multiplied by the three-phase sine wave of @(5)■ in the multiplier ae, and the signals (R4) (S, ) (T,
) is output. This signal (R,)(S,)(T,) is compared with the triangular wave (8W) by the comparator αD of spear 1, and the base signal of the inverter transistor fil f2) (31 base signal (T,)(T,) We get (T,). Also, we get the signal (
R,)(S,)(T,) is the voltage (-k) generated from the DC voltage generator α field in the adder (ilm).
They are compared with the triangular wave (8W) by the second comparator (total), and the base signal ('r4) (T-(T,)k of the inverter transistors (41+51+61) is obtained.

That is, a method is adopted in which the peak value of the output voltage is kept constant and the pulse width is changed by pulse width modulation (hereinafter referred to as PWM) to change the output voltage.

However, this conventional method uses a three-phase sine wave generator (
11, triangular wave generator a4), multiplier (1ω, adder Nishiki,
Comparison 1t(In(A)) and other complicated circuits were required.

In view of the above drawbacks, the present invention was made with the aim of achieving a sine wave-triangular wave modulation method with a simple circuit.
A DC voltage is input to a circuit in which three pairs of transistors are connected in series, and a signal is applied to the base of each of the transistors to control on/off of each transistor. In a transistor inverter device that obtains a three-phase AC voltage from the connection point of a pair of transistors, there is a lead/lead device that controls the DC voltage in proportion to the set frequency and stores the signal obtained by sine wave-triangular line modulation. the read-only memory, and a ring counter that performs a counting operation corresponding to the set frequency;
The present invention provides a transistor inverter device characterized in that a data signal stored at an address in a memory is applied to the base of the transistor.

Next, one embodiment of the present invention will be described based on FIG.

SI D is an inverter that rectifies the commercial three-phase AC voltage input from the input terminal @ (2) in the rectifier circuit @, converts the transistor (to), inductor (5), capacitor (to) (
A chopper circuit C32, which is controlled by a modulation circuit C31 (to be described later) and a diode (to), sets it to a predetermined voltage and outputs it to a terminal (to).

Three sets of transistors ncm, 67)-, which are connected in series by connecting the emitter at the front stage and the collector at the rear stage, are connected in parallel to this terminal (to) (to) (to). These three sets of front-stage transistors C39 (to) oi
The connection point between the emitter of the transistor (to) and the collector of the subsequent transistor (to) G (4G) is connected to the induction motor 0υ and receives the detection signal (-) via the transformer and rectifier circuit (c).
(V)fl connected to the detection terminal that outputs f)
The output line of M is connected.

A diode (43) is connected between the collector and the power supply terminal of each of the transistors (to)-11.

(2) is a voltmeter that measures the input voltage of the inverter C1'l).

Gυ is each transistor (
to) --- (a) base K, these transistors (
This is a modulation circuit that inputs a modulation signal for on/off control of (to)-m-) and also controls the chopper circuit (to).

(C) is a frequency setter, and the voltage (
νl) is output. The output terminal of this frequency setter (c) is a pulse train signal σ of frequency f corresponding to the input voltage.
) is connected to the ring counter (48) and to the chopper circuit control section (41).
41 is the voltage (V, ) and the detection signal (-f) of the inverter Qυ
), and by this input, the chopper circuit 03
Controls the voltage proportional to the set wave number to terminal c33 (b)
output in between.

The ring counter decoy receives a pulse train signal (
360Xa4 that performs multiple operation using b) as a clock signal
The output terminal of this ring counter (double) is tightly connected to a read-only memory (ROM), and the ROM corresponding to the count value of this ring counter (c)
The data signal (T, ) (
T, )(T,)(T4)(T,)(T,) is read out and output from the output terminal 511 sa q 64)(to)(to) to the inverter (each transistor of 2υ(to)-11 Apply to one base.

Next, the signals stored in each address of the ROM 61 will be explained using FIG. This is obtained by determining a fundamental frequency and using a sine wave-triangular wave modulation method at this fundamental frequency.

In sine wave-triangular wave modulation, the R phase (A,
), 8-phase (A, ), and T-phase (mu, ) are converted into sine waves and triangular waves (A
Among 4), the base of the transistor (to) has an R phase (mu,
) is larger or more powerful than the triangular wave (Mu4) (A, ≧
A4)^The signal (T1) that becomes “H” only when the S phase (A2) is at the base of the transistor (to) is a triangular wave
) is greater than or equal to (A2≧A4) A signal (T2) that becomes rHJ only when IQ is greater than or equal to (A2≧A4); .

≧A4) 1) A signal (T, ) that becomes rHJ only when Q is input.

In addition, the base of each transistor (to) c (1 m) in the subsequent stage has a rise time of Δt, not congruence with the base signal (T, ) (T2) (T5) of the transistor (to) OD in the previous stage. , and the fall time is accelerated by Δt (T4), (T5), and (T6), that is, T−2Δt.

1 T5=〒2-2Δt1 T6-〒, -2Δt.

is input. This Δt4 time is for preventing the transistors in the front and rear stages from being turned on at the same time and being destroyed, and is approximately 50 to 50 P seconds.

The conditions for finding the angle at which this signal (T,) = - (T6) becomes rI (J) are: (a) The period of the triangular wave is 40 degrees,
(2) If the wave height of a sine wave or a triangular wave is expressed in units of 0 degrees, the following tables 1 and 2 are used.
It will look like a table.

In addition, in these tables, the rHJ signal is set to "1", and the rHJ signal is set to "L".
The signal is expressed as "0", "↑" indicates that it went from "0" to "11" at this angle, and "↓" indicates that it went from "1" to "0" at this angle. .

(See next page) Based on Tables 1 and 2, the correspondence between addresses and signals when written in the order of KROM61m addresses at angles of 0.2 degrees is explained. 6 Table shows. In addition, the maximum count value of the address of ROM61 and the ring counter is 0.2.
540x1/(L2 depth 1800
Although it is necessary, it is not limited to every 0.2 degrees,
．． It is also possible to make the interval less than 2 degrees or more than 12 degrees, in which case the number of required addresses of the ROM (to) also changes.

Note that it is a matter of course that the maximum count value of the ring counter changes in accordance with the number of addresses in the ROM.

(Next page below) Talent 3 table Next, the operation of this embodiment will be explained.

When a frequency corresponding to the rotational speed of the I4 motor 0υ is set using the frequency setter, a voltage signal (νi) corresponding to the set frequency is output from the frequency setter.

This voltage signal (ν,) is input to the chopper circuit control unit (41).Then, this chopper circuit control unit controls the chopper circuit (to), and if the set frequency is higher than the fundamental frequency, the terminal (to) is input to the chopper circuit control unit (41). (b) Make the voltage output to the terminal higher than the voltage at the fundamental frequency, and if the set frequency is lower than the fundamental frequency, make the voltage output between the terminals (to) higher than the voltage at the fundamental frequency. Therefore, a voltage proportional to the set frequency is output between the terminals (To) and (B).The output signal (-f) of the inverter Qυ is also input to this chopper circuit control section at the same time. However, this is to stabilize the output voltage.

Further, the voltage signal (νi) is transmitted to a voltage-frequency converter (4).
This generates a pulse train signal of frequency f (f
It is converted to l and output. This signal (fl) is input as the clock signal of the ring counter (incorporated).Then, the ring counter (48) counts the clock signal and reads out the data signal written in the address of ROM5I corresponding to this count value. , the corresponding transistor (to) −
--f4 (input to the base of I, transistor (to))-
Controls on/off of t41.

In this way, the inverter clO(1) chopper circuit (
(To) becomes the voltage peak value corresponding to the set frequency, and even if the set frequency changes, if the set frequency is higher than the fundamental frequency, it will be shorter, and if it is lower, it will be longer, so the modulation signal will remain the same, only the period changes. The waveform is always the same at all angles. Therefore, the inverter output line ([1) (V), (
V) The wave height and period are different between ■ and ■0, but the difference between Figure 4 (U
-V), (V-W), and (W-U) output voltages are obtained.

That is, pulse amplitude modulation (PAM) and pulse width variation11
It is intermediate between il (PWM).

According to the present invention, there is no need for a complicated circuit consisting of a three-phase sine wave generator, a triangular wave generator, a multiplier, an adder, a comparator, etc., and the sine wave can be generated by storing a waveform signal according to the ROMK angle. - Triangular wave modulation method can be achieved with a simple circuit,
This allows the inverter circuit to be simplified.

[Brief explanation of drawings]

Figure 1 is a circuit diagram of a conventional transistor inverter device.
Figure 2 is a modulation circuit diagram as described above, Figure 3 is a circuit diagram of a transistor inverter device showing an embodiment of the present invention, and Figure 4 is an explanatory waveform diagram. (C) (To) C37) (To) (To) (Memorial... Transistor, (C) Fist ring counter, 6I#-Read-only e-memory.

Claims (1)

[Claims] (1) A DC voltage is input to a circuit in which three pairs of transistors connected in series are connected, and a signal is applied to the base of each transistor to control on/off of each transistor. In a transistor inverter device that obtains a three-phase AC voltage from a connection point of a pair of transistors connected to a transistor, the DC voltage is controlled in proportion to a set frequency, and a signal obtained by sine wave-triangular wave modulation is stored. It is equipped with a read-only memory and a ring counter that performs a counting operation in accordance with the set frequency, and receives a data signal stored at an address of the read-only memory that corresponds to the count value of the ring counter. A transistor inverter device characterized in that a voltage is applied to the base of the transistor.