JP2517915B2 - Hysteresis comparator type current tracking type inverter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to an improvement in a hysteresis comparator type current tracking type inverter.

[Prior Art and Problems] FIG. 3 shows a conventionally known hysteresis comparator type current tracking type inverter.

As shown in the figure, for the DC power source E, a switching element
The S ₁ and S ₃ in series, also connects the switching element S ₂ and S ₄ in series, each switching element regenerative diode D ₁ to D ₄ between each of terminals of the switching elements S ₁ to S ₄ Connected in the reverse direction of the energization, and with the switching element D ₁
Connected to one end of the load 1 via the source current reactor L ₀ that suppresses current change from the connection point of D ₃ , and the other end of the load 1 is connected to the connection point of the switching elements S ₂ and S ₄ to form an inverter circuit. To be done.

Reference numeral 2 is a current detector for detecting the inverter load current, and its output signal is input to the error detector 3. Although not shown, the error detector 3 inputs a current set value from a current setter and detects an error of the inverter load current with respect to the set current. Reference numeral 4 denotes a hysteresis comparator, the output signal of which is input to the driving amplifiers 6-1 and 6-4 for the switching elements S ₁ and S ₄ through the inverting circuit 5, and the switching elements S ₂ and S 4. amplifier for driving to the ₃ 6
2, 6-3 are directly input to the hysteresis comparator 4, and the polarity of the hysteresis comparator 4 is H.
Whether the level is (positive) or L (negative) is determined, the output signal from the hysteresis comparator 4 is amplified, and the switching elements S ₁ and S ₄ are closed and S ₂ and S ₃ are opened. In the opposite of this, energization control of the inverter circuit is performed.

FIG. 4 is an explanatory diagram of an operating state of the inverter shown in FIG.

The inverter load current is detected, the error between this value and the set value is found, and the switching elements S ₁ , S ₄ , and
Alternatively, S ₂ and S ₃ are operated. In the figure, 20 indicates a current setting value, 21 indicates a hysteresis width, and 22 indicates an inverter load current.

The inverter load current (output current) 22 is detected, the error between this value and the current setting value 20 is calculated, and the polarity is, for example, L
When it is (negative), the switching elements S ₁ and S ₄ are operated, and when the polarity is H (positive), the switching elements S ₂ and S ₃ are operated and the load including the source reactor L ₀ is applied. Apply the positive or negative voltage to make the inverter load current follow the set value of 20.

In general, the rate of change of the inverter output current is larger than the rate of change of the set value in all cases.
The reason is that if the rate of change of the inverter output current is smaller than that of the set value, it cannot follow.

In this case, for example, the inverter output current may be reduced according to the output of the hysteresis comparator even while the set value is increasing. Further, even when the set value does not change much, the inverter output current is repeatedly increased and decreased.
This is also a feature of the hysteresis comparator.

Since it operates in this way, it is necessary to increase the rate of change of the inverter output current in order to improve the followability to the current setting value. It is necessary to narrow the width. However, in both cases, there is a problem in increasing the number of times of switching, increasing the capacity and increasing the accuracy in terms of switching loss of the element and speed.

[Means for Solving the Problem] The present invention has been made for the purpose of reducing the number of times of switching and improving the followability to a current set value and the follow-up accuracy to a set value in the above-mentioned conventional hysteresis comparator type current follower inverter. In addition to the conventional tracking type inverter described above, a circuit that further detects a change in the current setting value and determines the polarity thereof and outputs the circuit, and a circuit that determines the polarity of the inverter output current. A latch circuit that latches the output of one polarity determination circuit when the hysteresis comparator changes (rising and falling),
Furthermore, by attaching a control circuit that determines the switching mode by the output of the latch circuit and the output of the hysteresis comparator, the inverter output current is controlled by the energization control of the switching elements S ₁ , S ₄ or S ₂ , S ₃ , and at a certain control stage, A return circuit is formed by a switching element and a regenerative diode to reduce the number of operating times of the switching element by the output of the hysteresis comparator, which is caused by the fluctuation of the conventional inverter output current, and at the same time improve the tracking accuracy.

 The present invention will be described below with reference to the embodiment shown in FIG.

 The same parts as those in FIG. 3 are designated by the same reference numerals.

Switching elements S ₁ and S ₃ are connected in series, and switching elements S ₂ and S ₄ are connected in series to a DC power source E, and a regeneration diode D is provided between the terminals of each of the switching elements S _{1 to} S _{4. 1 to} D ₄ are connected by reversing the energizing direction and the energizing direction of the switching elements, respectively, and connecting points of the switching elements S ₁ and S _{3 and} the connecting points of S ₂ and S ₄ that are parallel to each other with respect to the DC power source E. The point 1 is connected to the load 1 via the source reactor L ₀ that suppresses the current change to form an inverter circuit, and the output signal from the current detector 2 that detects the inverter output current is input to the error detector 3. On the other hand, the input of the current setting value to the error detector 3 and the input of the detected error signal to the hysteresis comparator 4 are the same as those shown in FIG.

A transistor or the like is used as the switching element.

Reference numeral 7 is a current change amount detection circuit for inputting the current set value and its polarity determination circuit, and detects whether the change amount of the current set value which changes with time takes H (positive) or L (negative). To do. Reference numeral 8 is a circuit for detecting the change in the current set value and determining the extreme value thereof.
Is a latch circuit that receives the H (positive) and L (negative) signals as input, and holds one of the above signals when the hysteresis comparator 4 changes (rises and falls) and the AND circuit. Input to 11-1 or 11-2. In FIG. 1, terminal 8-1 is a signal terminal that becomes H when the current change of the current setting value is positive, and 8-2 is a signal terminal that becomes H when the current change is negative.

A load current polarity determination circuit 9 is connected to the load current detection circuit and determines the polarity of the inverter output current.

The output side of the polarity determination circuit 9 is directly connected to the AND circuits 11-1, 11
-4 and an AND circuit 11 via an inverting circuit 5-2.
-2, 11-3, the output side of the hysteresis comparator 4 via the inverting circuit 5-1 to the AND circuit 11-4,
Further, it is directly connected to the AND circuit 11-3 and the latch circuit 8.

FIG. 2 is an operation explanatory view of the inverter, and the current setting value is illustrated as a sine wave for convenience of description.

The current polarity of the determination result of the load current polarity determination circuit 9 of the inverter output current is indicated by H-L in the upper stage, and the signal of the determination result by the current setting value change detection and the polarity determination circuit 7 is H-L in the next stage. L-H, and the output signals H and L of the hysteresis comparator 4 are shown in the third stage.

[Operation and Action] In the figure, the operation for eight divisions of the polarity (H, L. hereinafter referred to as level H. level L) indicated by the hysteresis comparator 4 will be described.

In the classification, the hysteresis comparator 4 from the previous stage
Is at the L level, the signal from the current setting value change detection and polarity determination circuit 7 is at H (positive), and the polarity is indicated by the load current polarity determination circuit 9 at H (positive).
The switching elements S ₁ and S ₄ are closed by 11-1 and 11-4, and the load including the current limiting reactor L ₀ is energized, and the hysteresis comparator 4 reaches the level H during this period.

In the division, the signal H (positive) from the current setting value change detection and its polarity determination circuit 7 is still present and the signal from the load current polarity determination circuit 9 is H (positive), but the hysteresis comparator 4 is at level H. By reaching
Switching element S ₄ is open.

As a result, the element through which the current flows is the switching element.
S _1, the reflux mode in inverter caused by the regenerative diode D _2, the load current including the load 1 and the current limit reactor L ₀
It decays with a time constant of LR, forms a flat slope, and the hysteresis comparator 4 reaches the level L.

 Division works under exactly the same conditions as division.

 In the division, the operation is performed under the same conditions as the division.

In the classification, the current setting value is in the falling state and the hysteresis comparator 4 is in the level H state.
The signal from -1 to AND circuit 11-1 disappears and terminal 8
-2 signal goes into the AND circuit 11-2, but the switching element S ₁ goes from the closed state in the section to the open state, and the return current flows through the regenerative diodes D ₂ and D ₃ in the section, during which the output current Rapidly falls, and the hysteresis comparator 4 reaches the level L.

In the classification, the hysteresis comparator 4 is set to level L
As the switching element S ₄ is closed, the load current is circulated by the switching element 4 and the regenerative diode D ₃ .

In the section, the switching element S ₄ opens when the hystericin comparator 4 reaches the level H in the section, and the load current flows back by the regenerative diodes D ₂ and D ₃ without involving other switching elements.

Although the operation has been partially described above, the inverter load current can be controlled so as to follow the change in the set current value.

The switching operation of the inverter of the present invention will be summarized as follows with reference to FIG.

(1) When the load current is positive (H) is, S ₁ is turned off to S _2, S _3, S ₄ only on, performs off, and when a negative polarity (L) is, S _1, S ₄ Is turned off, and only S ₂ and S ₃ are turned on and off.

(2) Even when determining the polarity (positive or negative) of the current change in the current setting value, S ₂ is always turned off when increasing (positive) and always decreasing (negative)
Turn off S ₁ .

(3) when the load current is positive (H) is従Gai the hysteresis comparator output, on the S _4, are turned off. When the load current is negative (L) is the S ₃ on, it is turned off in accordance with the hysteresis comparator output.

This will be described in comparison with the conventional device of FIG. 3 from the viewpoint of function. In the conventional device, the inverter load current is decreased (di / dt is negative) even if the temporal change of the current setting value is positive. There was a mode in which the inverter load current was increased (di / dt was positive) even when the mode changed and the temporal change in the current setting value was negative.

On the other hand, in the present invention, in the case of the increase of the current set value, when the load current of the inverter reaches the upper end of the hysteresis width, the inverter load voltage is set to zero to reduce the output current of the inverter (flat When the hysteresis output current reaches the lower end of the hysteresis width of the set value after the set value exceeds the inverter load current, the mode is changed to the inverter load current rising mode again. ing. Current setting value
The same applies when di / dt is negative.

That is, when the current setting value is increasing, the inverter load current is not decreased, and when the current setting value is decreasing, the inverter load current is not increased and the number of times of switching is reduced. .

[Effect] In the device shown in FIG. 3, the number of switching times is 1
Although the cycle was 22 times, the first improved system shown in FIG.
In the apparatus shown in the figure, the number of times of switching was 12 times per cycle. Although a large-sized switching element generally operates slowly, according to the present invention, since the number of times of switching can be reduced, a large-current inverter can be constructed.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention. FIG. 2 is a diagram for explaining the operation of the embodiment shown in FIG. FIG. 3 shows the circuit of a conventional hysteresis comparator type current tracking type inverter. FIG. 4 is an operation explanatory view of the inverter shown in FIG. S _{1 to} S ₄ ...... Switching element, D _{1 to} D ₄ ...... Regeneration diode, L ₀ ...... Current limiting reactor, 1 ...... Load, 2 ...... Current detector, 3 ...... Polarity judgment circuit, 4 ... ... Hysteresis comparator, 5 ... Inversion circuit, 7 ... Current setting value change detection and polarity determination circuit, 9 ... Load current polarity determination circuit, 8 ... Latch circuit, 11 ... AND circuit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-59-123476 (JP, A) JP-A-62-230366 (JP, A) JP-A-62-290361 (JP, A) JP-B-53- 33734 (JP, B2)

Claims (1)

(57) [Claims] 1. A circuit in which switching elements S ₁ and S _{3 in} which regenerative diodes D ₁ and D ₃ are respectively connected in parallel are connected in series and a switching element S in which regenerative diodes D ₂ and D ₄ are respectively connected in parallel. A circuit in which ₂ and S ₄ are connected in series is connected in parallel to the DC power source E, and the switching elements in series are connected.
An error detector 3 for detecting an error between a current setting value and a load current detection value in an inverter circuit in which a current limiting reactor L ₀ and a load 1 are connected in series between the connection points of S ₁ , S ₃ and S ₂ , S _4. And a hysteresis comparator 4 for generating an H signal when the error signal from the detector 3 exceeds a first predetermined value and an L signal when the error signal falls below a second predetermined value, and a current setting value. Detecting a change in the set current as an input and determining the polarity, and outputting a H (positive) signal when the current change is in the increasing direction, and outputting an L (negative) signal when the current is changing, and its polarity Judgment circuit 7 and the polarity of the inverter load current are judged and H
A load current polarity determination circuit 9 that outputs a (positive) or L (negative) signal, an H (positive) or L (negative) signal from the current setting value change detection and polarity determination circuit 7, and an H from the hysteresis comparator 4. Alternatively, a latch circuit 8 for inputting an L signal is provided, and one input terminal of an AND circuit 11-1 connected to the preceding stage of the switching elements S ₁ , S ₂ , S ₃ and S ₄ driving amplifiers has one of the current H (positive) or L input to the latch circuit 8 from the setting value change detection and polarity determination circuit 7
One input terminal of the AND circuit 11-2 is connected to the latch circuit terminal that generates the same signal as one of the (negative) signals, the other input terminal is connected to the output terminal of the load current polarity determination circuit 9, H (positive) or L (negative) input to the latch circuit 8 from the current setting value change detection and polarity determination circuit 7
Of the load current polarity determination circuit 9 is connected to the latch circuit terminal that outputs a signal opposite to the signal of
Of the AND circuit 11-3 is connected to the output terminal of the hysteresis comparator 4, and the other input terminal is connected to the terminal of the load current polarity determination circuit 9. Connected via the inverting circuit 5-2, one input terminal of the AND circuit 11-4 is connected to the output terminal of the hysteresis comparator 4 via the inverting circuit 5-1.
The other input terminal is connected to the output terminal of the load current polarity determination circuit 9 and is a hysteresis comparator type current tracking type inverter.