JPS58207876A - Voltage type inverter device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a voltage source inverter device applied to speed control of an AC motor.

FIG. 1 shows an example of a block diagram of a conventionally known voltage source inverter device for an AC motor.

As shown in Figure 1, the main circuit includes forward conversion l#1 for converting alternating current to direct current, glue handle 2 for DC smoothing, capacitor V3 for DC smoothing, and inverse conversion for converting direct current to alternating current. 4 and an AC motor 5 as a load. The l1ilf converter 1 in this example is formed of a diode, and the output voltage and output frequency are all controlled by the inverter 4. The inverse transformer 64 is formed from a gate turn-off thyristor, a conventional thyristor, a transistor, or the like.

On the other hand, the control circuit includes a current transformer 6 as an output current detector,
A transformer 7 as an output voltage detector, rectifier circuits 8 and 9 that rectify the output current or voltage detection signal detected by these, and output a speed command signal of voltage according to the desired speed set. A speed setting device 10, a voltage frequency conversion port M (V/F) 11 that outputs a pulse signal with a frequency proportional to the speed command signal, and a subtraction device that subtracts the voltage detection signal from the speed command signal and outputs a difference signal. 12, and an automatic voltage controller (AVRl) that outputs a control signal for controlling the output voltage according to the speed command signal based on this difference signal.
13. A subtracter 14 that subtracts the current detection signal from this control signal and outputs a difference signal; and an automatic controller that outputs a control signal for adjusting the output current according to the speed command signal based on this difference signal. Current controller (ACR) 15, this ACR
a pulse width modulation circuit (PWM) 16 that outputs a pulse width modulated ignition pulse signal according to the control signal output from V/Fil and the pulse signal output from V/Fil;
A pulse amplifier (AMP) 17 amplifies this ignition pulse signal and sends it to the thyristor of the inverter 4.

The basic operation of the voltage source inverter device configured as described above is based on the speed command signal set by the speed setting device 10. The frequency of the motor is V/FIIK!
Voltage control loop consisting of voltage F'1AvR13, i.e., transformer 7→rectifier circuit 9-+AVR13-+A
It is controlled by a loop consisting of CR15-+PWM16-+AMP17→inverter 4. In addition, the current transformer 6
→ Rectifier 8 → ACR, 15 → PWM16 → AMP17 →
The flow control loop formed by the inverter 4 is a minor loop, and is primarily used to maintain the output current below a predetermined level, or may not be provided in particular.

When starting the electric motor using the above-described conventional voltage source inverter device, the motor is started with the speed setter 10 set to the minimum position, and then the motor is started so as to gradually increase the speed to a desired speed. Similarly, when decelerating or stopping the motor, the setting value of the speed setting device 10 is gradually lowered, and both the output frequency and the output voltage are lowered, thereby decelerating the motor.

However, when the electric motor enters the regeneration mode during deceleration operation, the voltage of the main circuit DC section may be abnormally increased due to the regenerated power. This abnormal overvoltage can cause damage to semiconductor elements such as diodes and thyristors that constitute the forward converter 1 and the inverse converter 4, or to the smoothing capacitor 3 and the like.

Here, the voltage increase in the DC section in the regeneration mode will be explained in more detail.

Now, let N be the initial rotation speed of the motor before the deceleration value. , if the load torque and output at that time are 1ToIPa, then the load torque T. Hato becomes.

The deceleration torque T required for ri, and all flywheel effects that impede the motor and its load are GD''.

Here, the difference torque between the load torque T0 and the deceleration torque TD is T1, that is, Ts = To TD -...-
... (3) Then, the motor output P generated by this torque T becomes. (1) When the deceleration torque Tt+ is large and Tt becomes negative, the motor output P1 in equation (4) becomes a regenerative output. In other words, this regenerative current is sent to the inverter device, and the voltage of the DC section is increased according to the output P, which may lead to damage to the above-mentioned components of the inverter device.

Therefore, in order to prevent the abnormal rise in the DC voltage due to the regenerative operation of the electric motor, conventional methods have been used to stop the inverter device during deceleration and disconnect it from the electric motor, or to install a load resistor in the DC section as shown in Figure 2. -1fll= is provided, and a method has been devised in which the regenerative current is consumed by this resistance and the rise in DC voltage is suppressed.

However, in the former case, the deceleration of the electric motor becomes a natural deceleration, so it has the disadvantage that it is only possible to decelerate to the desired rotation speed and operate at a constant speed. Since direct current flows through the resistor, losses are increased and the efficiency of the inverter device is reduced.

SUMMARY OF THE INVENTION An object of the present invention is to provide an inverter device that can suppress abnormal increases in DC power voltage due to regenerative current without increasing loss, and can control deceleration speed operation.

The present invention prevents the DC power voltage from exceeding the set upper limit value.
By controlling the deceleration rate of the electric motor, it is possible to suppress an abnormal increase in DC section voltage due to regenerative current without increasing recoil, and to make it possible to control deceleration operation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on illustrated embodiments.

FIG. 3 shows a block diagram of an embodiment of the present invention. In the figure, parts having the same functions and configurations as those of the conventional example shown in FIG.

As shown in FIG. 3, an isolation amplifier 19 for detecting and amplifying the voltage of the DC section and a speed ramp @l,in circuit 20 are added, and a speed command output from the speed setting device 10 is added. The signal is passed through the speed ramp control circuit 20 to V/F 1
1 and is input to the subtracter 12. Further, the speed slope control circuit 20 receives a DC section detection voltage from the isolation amplifier 19 . ....

The speed gradient control circuit 20 has the circuit configuration shown in FIG. 4.

As shown in FIG. 4, a speed command signal V is connected to the terminal 21.
, and a DC voltage detection signal V is input to the terminal 22. Terminal 21#: is connected to the operational amplifier ICs forming a transmitter circuit that presses W through resistors R,, yt)
Connected to the input end. I.C.

(4) The input end is grounded, and the output end is resistor R1゜R4? to +Vc through resistors Ry, Re'fr
It is connected to Vcc via. The connection point between the resistors R1 and R4 is connected to the housing resistors R5 and 'R1 through the diode D.
The connection point with 6 is connected to the input terminal of IC8 via diode D. Moreover, the output terminal of IC, is a resistor R
It is connected to the H input terminal of IC1 forming an integrating circuit through an angle of 8°. The input terminal (A) of these ICs is grounded, and the output terminal is connected to the feedback circuit of capacitor C1.
at the input end and also at the signal output end 23 of the speed ramp control circuit;
Furthermore, resistance R1,.

At the (c) input terminal of IC4 forming an inverting circuit via
each connected. The (g) input terminal of this circuit C4 is grounded, and the output terminal is connected to the (c) input terminal via a feedback resistor RIB, and to the ←) input terminal of the ICt via a resistor R.

On the other hand, the terminal 22 is connected to the input terminal of IC50 via a resistor R6. This (c) input end is connected to an upper limit value setter VB via a resistor R1. The input end of the IC is grounded, and the output end is a capacitor C8, a resistor R0, and a diode D.

(c) to the input terminal through the parallel circuit of
: is connected to the input end of the IC through the input terminal.

The operation of the embodiment configured as described above will be explained below.

The speed ramp control circuit 20 receives the voltage signal of the speed command signal (2) from the speed setter 10 and receives the voltage signal of the DC voltage detection signal (V) through the isolation amplifier 19. In addition, the setting upper limit value signal set by the upper limit value setter VR,
4 corresponds to the DC part voltage that starts suppressing the slope of the speed command, and since the absolute value of v4 is normally larger than the absolute value of V, the output of IC, ■, becomes almost zero voltage. There is.

IC+ voltage limiter circuit, IC3 integration circuit and I
The closed loop circuit formed with the inverting circuit of C4 operates as a speed slope limiter circuit that controls the output signal 6 so that it does not change beyond a certain slope even if the speed command signal 2 changes stepwise. There is.

Here, the operation of the speed gradient control circuit 10 will be further explained in cases where the motor load is heavy and cases where the motor load is light, with reference to FIGS. 5 and 6.

When the load on the motor is heavy, the regenerative power during regenerative operation: As shown in FIG.
, the output voltage signal ■, instantaneously reaches the lower limit value −■,. becomes.

Further, the detection signal V of the DC section voltage is at a level □ which hardly changes before and after startup, if the voltage drop of the forward converter is ignored. It becomes. At this time, the output signal ■6 is the integral constant of XC8 and ■, as shown in FIG. 5(f).
T is raised at a slope determined by the level (lower limit - ■, .).

If you achieve the same level as Vlo in
,. will be maintained.

When the speed command signal V becomes zero stepwise at T3,
The output signal V of the motor C1 is the upper limit of the opposite polarity to that during acceleration■,
1, and begins to fall linearly with time at a slope determined by the integral time constant of C3 and the upper limit value I, -1 output signal V, a. Immediately after the start of deceleration, the DC streetcar pressure detection signal V is increased by the regenerated power, as shown in FIG. 5(C). At this time, VsFi reaches the maximum VSS, but V4o can be reached at the operation start level of the speed slope suppression circuit.
■. The output is linearly lowered at a constant slope. As a result, the electric motor is quickly decelerated and stopped at T4.

Next, when the load on the Hayabusa driver is light, the regenerated power during regenerative operation becomes large, and the signal voltages at each part become as shown in FIGS. 6(a) to ff). Figure 6(a)~
As can be seen from (f), the operation from TI at startup to constant speed operation is the same as in the ms diagrams (a) to (f). T
When a stop command is input at step 3 and deceleration starts,
Regeneration 1 [DC part voltage for current ■.

is increased to a level V corresponding to the setting level of the upper limit signal ■4 - ■4°. At T, which is delayed to , the output signal V of rc is −■, as shown in FIG. 6(e).

becomes a negative level voltage. This-■3. is the integrating circuit IC
8, the downward slope of the output signal V is proportional to the difference voltage (Vt+Vss) between the input signal V and tV, and T in FIG. 6(f).

As shown between T6 and T6, it becomes gradual.

Therefore, the deceleration of the electric motor is suppressed, and thereby the regenerated power is suppressed, so that the DC section voltage is maintained at a voltage corresponding to the set upper limit value 4 degrees or less. In this way, T.I.
When the detection signal V of the DC section voltage becomes less than ■4° at I, the input of the circuit C3 becomes ■2. Only, the output signal ■6
has the same downward slope characteristic as explained in FIG.

Therefore, according to this embodiment, the regenerative power is reduced by suppressing the deceleration rate, thereby suppressing the abnormal rise in the DC section voltage, so a regenerative load resistor etc. is used. This eliminates the need for this, eliminates the loss caused by this, and allows operation at a desired deceleration speed. %, multiple types of electric power can be generated by one inverter! This is even more advantageous when applied to a device that performs t-switching operation.

In the above embodiment, the forward converter is formed of a diode, and the frequency and output voltage are controlled by the inverse converter. However, the present invention is not limited to this. As shown in the figure, the forward converter 24f is formed of a thyristor and controls the output voltage by controlling the phase of this thyristor, and the inverse converter 4 is formed of a thyristor, which controls the output voltage only, and controls the frequency. Shain/
(-It can be applied in exactly the same way to ζ, and the same effect can be obtained.

In addition, the parts in FIG. 7 with the same reference numerals as those in the embodiment shown in FIG. 3 have the same functions and configurations, and are
is a channel splitter (RC), 26 is an automatic/(Russ phase shifter (APP)
S), 27 is a Norms amplifier (AMP).

As explained above, according to the present invention, it is possible to suppress an abnormal increase in the DC section voltage during regenerative operation without using a regenerative load resistor that increases loss, and moreover, it is possible to suppress the abnormal increase in the DC section voltage during regenerative operation. The effect is that it can be operated at high speed.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a conventional example, Fig. 2 is a block diagram of another conventional example, Fig. 3 is a block diagram of an embodiment of the present invention, and Fig. 4 is a block diagram of the embodiment shown in Fig. 3. Detailed circuit configuration diagram of the speed ramp control circuit, FIGS. 5(a) to (f) and 6
Figures (a) to (f) Operation explanatory diagram of the illustrated embodiment in 4 severe cases, w,
FIG. 7 is a block diagram of another embodiment of the present invention. 1.24... Forward converter, 4... Inverse converter, 5...
AC current machine, 10... Speed setter, 19... Isolation amplifier, 20... Speed slope control circuit, VR,... Upper limit value setter. Agent Patent Attorney Akio Takahashi Kaya 1, 2nd Eye, 50 Mu I I 1 17;
Tz no f4 #Otsu eyes

Claims (1)

[Claims] 1. In a voltage type inverter device that controls the speed of a load AC motor by converting input DC power into AC power with a frequency and voltage based on a speed command signal, when a deceleration command signal is input, DC power is Tokyo voltage is the upper limit set ffi
1. A voltage source inverter device comprising a speed slope control circuit for controlling a deceleration rate so as not to exceed .