JPS61199481A - Inverter - Google Patents

Abstract

PURPOSE:To rapidly and accurately control a regeneration by controlling a power regenerative switch element parallel to a power reactor rectifier on the basis of a voltage detection and a current direction detection to return the regenerative energy to an AC power source. CONSTITUTION:When a motor 6 normally rotates and is not in a regenerative brake state, 3-phase ACs are converted by a power factor 4 to a DC, and further converted by an inverter 5 to 3-phase AC, and supplied to the motor 6. When becoming a regenerative state, switches 21-23 are closed by the outputs of a voltage detector 13 and a direction detector 15, and a control signal is supplied to transistors Q1-Q6. The transistors Q1-Q6 are connected in parallel with power reactor rectifiers D1-D6, and the regenerative energy is returned therethrough to an AC power source.

Description

DETAILED DESCRIPTION OF THE INVENTION [Eleventh Industrial Field] The present invention relates to an inverter device for controlling and driving an AC motor, and more particularly to an inverter device equipped with a power regeneration circuit.

[Conventional technology]

Tanu's conventional inverter device for operating a conventional AC motor (induction motor or synchronous motor) at variable speed was constructed as shown in FIG. In Figure 4, 111121
+: 3+ is a three-phase AC power line, (4) is a forward conversion circuit, (5) is an inverse conversion circuit, (6) is an AC motor, (71 (
8) is a pair of DC lines, (9) is a capacitor for voltage flat steel, 00) is a resistor for energy discharge, (111 is a transistor, and 02) is a voltage configuration (RO) path. Note that the inverse conversion circuit (5; includes a three-phase bridge-connected transistor Q and a power regeneration diode D.

With this circuit, when the electric motor 16) is stopped or at axle speed,
When the electric motor 16) operates as a generator, the voltage generated in the winding of the electric motor (6) also turns on the diode D, and regenerated energy is absorbed into the capacitor (9). The regenerative energy is large and the DC line +7)
(When the voltage between 81 and 81 becomes higher than a predetermined value, the output of the heavy pressure detection circuit (12) turns on the transistor 011, and the resistor (1, +11) consumes energy, achieving regenerative braking.

[Problems that the invention attempts to solve]

When the regenerative braking condition frequently occurred in the circuit shown in FIG. 4, current frequently flowed through the resistor port 0) and the temperature rose abnormally.

For this reason, it was necessary to increase the power capacity of the resistance 0()). It was. In order to prevent the transistor "old" from turning on in response to the voltage VD between the pair of DC lines +71 and +81 during normal operation,
In order to turn on the transistor (1,]J'Y, the level of the reference voltage (base voltage) vDS had to be set high as shown by the broken line in FIG.

In addition, there was a problem that regeneration did not start quickly, and a problem that the withstand voltage of the capacitor (9) had to be increased. As mentioned above, due to the large capacitance of the resistor GO and the high withstand voltage of the capacitor (9), if these components become large, even if the forward/inverse conversion circuit is made small, the inverter device as a whole will become large. Ta. Unfortunately, energy was consumed when the resistance was 0ω, so overall efficiency could not be improved. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an inverter device that can quickly and appropriately perform regeneration control with little power loss.

[Tanu's means of solving problems]

The inverter device of the present invention, which achieves the above objects, includes a forward conversion circuit comprising a forward conversion rectifier connected to an AC power supply, and a power regeneration circuit connected in antiparallel to the +1IiIII conversion rectifier. an inverse conversion circuit consisting of a switch element for inverse conversion, a switch element for inverse conversion connected between a pair of DC lines of the forward conversion circuit and an AC motor, and a rectifier element connected in antiparallel to the switch element for inverse conversion. A capacitor connected between the pair of DC lines, a DC voltage detection circuit that detects the voltage between the pair of circulating lines, and a current flowing through the DC line between the capacitor and the inverse conversion circuit. a current direction detection circuit that detects that the direction is reversed; a reference voltage generation circuit that generates a voltage that indicates the level at which the regeneration switch is turned on; and DC detection obtained from the DC' heavy pressure detection circuit. a voltage comparison circuit that compares a voltage with a reference voltage obtained from the reference voltage generation circuit and determines whether a voltage relationship exists that allows power regeneration through the power regeneration switch element; A signal indicating that the direction of the current obtained from the circuit is reversed, and a signal indicating that the power regeneration switch element Y'lf obtained from the voltage comparison circuit is capable of performing a force regeneration operation. and a regeneration control circuit that controls the power regeneration switch element to be in the on state within a period in which the power regeneration switch element and the power regeneration switch element simultaneously occur.

[For production]

In the above inverter, when the motor is rotating normally, the DC voltage of the forward conversion circuit is converted into AC by the inversion circuit. When the motor enters a regenerative braking state, regenerative energy is returned to the capacitor through the regenerative rectifier. If the direction detection circuit detects that regeneration is in progress and at the same time detects that the recirculation voltage is higher than FN and the main voltage, the regeneration switch element is turned on only within this period, and regeneration starts. The energy is returned to the father's mail. Since the device of the present invention is provided with a flow direction detection circuit, regeneration control is not performed solely in response to the magnitude of the DC voltage. That is, it can be determined whether the DC line voltage is high due to normal ripple or whether the °C voltage is high based on regeneration. Therefore, regeneration control is performed quickly and appropriately.

〔Example〕

Next, FIG. 1 showing an inverter device according to an embodiment of the present invention will be explained. However, in this Figure 1, the symbol mountain ~
Since what is indicated by (9) is substantially the same as what is indicated by the same reference numerals in FIG. 3, the explanation thereof will be omitted. In addition to the sixth diodes D1 to D6, first to sixth transistors Q1 to Q6 are included as power regeneration switching elements. first to sixth transistors Q,
~Q6 is connected in antiparallel to the first to sixth diodes D and ~D6, and is controlled to be reversely converted during regeneration.

The inverse conversion circuit (5) includes seventh to twelfth transistors Q as inverse conversion switching elements connected in a three-phase bridge;
In addition to ~Q+t, seventh to twelfth diodes D7 to T are connected in antiparallel to this as power regeneration rectifying elements)
Including n.

(I3) is a DC voltage detection (b) path, which is connected to a pair of curved lines +71 (81) and generates a DC voltage VD. Inverse conversion circuit] 5) and the DC line (connected outside the 81K plane. (I5) is a current direction detection circuit that detects the direction of current according to the direction of the voltage across V and resistor -, and It generates a high level output when in the direction.

(15a) is a reference voltage generation circuit, which is composed of a rectifier circuit connected to the AC cylinder 1 source line +l l (21++3+), and generates a reference voltage vDS corresponding to the AC power supply voltage.

(16) is a comparison circuit that compares the detected DC voltage VD of the voltage detection circuit (13) with the reference voltage vDS as shown by the solid line in FIG. 2 obtained from the reference voltage generation circuit (15j), and This circuit also generates a high level output when the detected DC voltage VD becomes high.

(17) is a regeneration control circuit, which consists of three comparator circuits that act as signal sources: u8, F) 3 horn N OT circuit c!
1) 1251 t21i1 and an AND gate 071 for determining the regeneration w3, and the six output lines are connected to the bases of the sixth transistors Q and Q6.

Reference numeral 1 [29+ +301 is a phase current detector for each phase, which is provided at a position where the instantaneous value of the regenerative current is detected.

(3) J is a reference phase Kamelyu Hakugo generation circuit, which detects the line voltage of the turtle line +ll 121 +31 with, for example, a transformer, and generates a phase voltage that has a phase lag of 30 degrees with respect to this line voltage. For example, it is a circuit that generates a reference phase current signal obtained from the secondary winding of a transformer and indicating a phase current that matches the phase voltage.

The comparison amplifier circuit 08J f+ 91 C20) uses the detected DC voltage obtained from the current detector (28I (29) (g)) of each phase and the detected DC voltage obtained from the reference phase commercial signal generation circuit (3]J. When the detected phase current signal is smaller than the quasi-phase commercial signal 8, a high level output is generated, and when the opposite is true, an al/hel output is generated.

Next, the operation of the circuit shown in FIG. 1 will be explained. Now electric motor 16
) rotates normally and is not in a regenerative braking state, the forward conversion diodes D1 to D6 convert three-phase AC to DC, and this DC is converted to three-phase AC by transistors Q and Qn. Ru. During this period, regenerative transistors Q, ~Q6
and the regeneration diodes D, ~I)+t are kept off.

On the other hand, in the regenerative state, the detected normal pressure between the pair of DC lines +71 and +81 obtained from the voltage detection circuit Q3+
If D is higher than the reference voltage VDs, the comparator circuit (I6)
output goes high, and the direction detection circuit (15) generates a high level output indicating reverse current.

Then, these two high level outputs are connected to an AND gate (27
), the AND game) [The output of 271 becomes high level 9, the first, second, and third switches 12
1) +221 and +231 are turned on, and it becomes possible to supply the il control signal to the transistors Q, -Q. The regenerative state is not detected only by voltage, but is determined by considering the direction of the current, so what is the difference between ripple and voltage rise during regeneration? The base S voltage VD8 for regeneration detection can be set low enough to be applied to the ripple as shown by the solid line in FIG.

The comparison surface M (181 discharge (20) of each phase compares one regenerative current signal and the reference current signal 1s as shown in Fig. 3, and outputs a high level when one detected current signal is lower than the reference current signal 1. Low level output occurs when the level is high.

Now, if the output of the comparator circuit 08) is at a high level and the switch circuit 08) is on, then the second transistor Q
, turns on and regenerative current flows. At this time, the second transistor Q is supplied with a low level signal by valving the NOT circuit (241), so it is kept off.When the transistor Q is turned on, the detected current signal ID changes to the violent current signal. ■When the 8 yen also increases, the output of the comparator circuit (181 becomes low level and the transistor Q1 is turned off.The regenerative current is controlled by the instantaneous value in this way), the phase of the phase voltage and phase current is changed. It is possible to perform regeneration with an unmatched power factor.

The same inventory +m+ as in the comparison circuit (18) is also performed in the comparison circuits (1, 9) +20) of other phases.

η→, by the motive 16) stopping or rotating normally.

When reverse current is no longer detected, the switch's old 221
(23j is controlled off, transistors 1 to Q
6mo is kept off.

Although the embodiments of the present invention have been described above, the invention is not limited thereto and can be further modified. For example, instead of the transistors Q1 to Qn, self-extinguishing type transistors, FETs, etc. may be used.Instead of the three switches t2] + +221 +231, six switches combined with the transistors Q1 to Q6 can be used. A switch may also be provided. Comparison circuit (181Q9) A power supply that always generates a high-level or low-level voltage is provided in the circuit that generates the controlled output from (20), and based on this, the transistors Q1 to Q6 are operated as inverters. Form a control signal to be distributed to the
(27) may be used for control.

[The power of invention]

As is clear from the above, according to one aspect of the present invention, the power regeneration switch element parallel to the forward conversion rectifier is controlled based on voltage detection and current direction detection to return regenerated energy to the AC power source. Low consumption can be achieved. Since the start of regeneration is not decided based on voltage alone, but the direction of current is taken into consideration, the voltage level at which regeneration is started can be lowered, and regeneration can be controlled quickly and accurately. Furthermore, if you lower the voltage level at the start of 1st regeneration,
The withstand voltage of the capacitor between a pair of current lines can be lowered. This eliminates the need for a resistor that consumes regenerative energy, making it possible to downsize the device.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an inverter device according to an embodiment of the present invention, FIGS. 2 and 3 are waveform diagrams of various parts of FIG. 1, and FIG. 4 is a block diagram of a conventional inverter device. Mountain t21131...AC power line, (4)...Forward conversion circuit, +51...Inverse conversion circuit, (6)...AC motor, +71 +81...DC line, (9)...
Capacitor, (13)...DC voltage detection circuit, 0. I
I... Resistor for current direction detection, Q5a)... Reference voltage generation circuit, Ob... Comparison circuit, (17)... Regeneration control circuit.

Claims (1)

[Claims] (1) A forward conversion circuit consisting of a forward conversion rectifier connected to an AC power source, a power regeneration switch element connected antiparallel to the forward conversion rectifier, and a pair of DC lines in the forward conversion circuit. and an AC motor; a rectifying element connected in antiparallel to the inverse conversion switching element; and a capacitor connected between the pair of DC lines. a DC voltage detection circuit that detects the voltage between the pair of DC lines; and a current direction that detects that the direction of the current flowing in the DC line has become reversed between the capacitor and the inversion circuit. a detection circuit; a reference voltage generation circuit that generates a voltage indicating a level for turning on the regeneration switch element; a DC detection voltage obtained from the DC voltage detection circuit and a reference voltage obtained from the reference voltage generation circuit; A voltage comparison circuit that compares and determines whether or not there is a voltage relationship that allows power regeneration through the power regeneration switch element, and a current direction detection circuit that determines that the direction of the current obtained from the current direction detection circuit is opposite. The power regeneration switch element is turned on within a period in which a signal indicating that the power regeneration switch element is capable of operating the power regeneration switch element obtained from the voltage comparison circuit is generated at the same time. An inverter device consisting of a regeneration control circuit for controlling.