JP2517930B2 - Current tracking type inverter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement in a current tracking type inverter.

[Prior Art and Problems] FIG. 2 shows a conventionally known hysteresis comparator type current tracking type inverter.

As shown in the figure, for the current source E, the 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 S ₁
It is connected to one end of the load 1 via the current limiting reactor L ₀ that suppresses the current change from the connection point of S ₃ , the other end of the load 1 is connected to the connection point of the switching elements S ₂ and S ₄ , and the inverter circuit is Composed.

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 via the opposite circuit 5, and the switching elements S ₂ and S 4 are also provided. amplifier for driving to the ₃ 6
The hysteresis comparator 4 is configured to be directly input to 2, 6-3, and determines whether the polarity of the polarity is positive (H) or negative (L), and outputs the hysteresis comparator 4. The signal is amplified, the switching elements S ₁ and S ₄ are closed, and S ₂ and S ₃ are opened, or the opposite is done, so that energization control of the inverter circuit is performed.

FIG. 3 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 calculated, and the switching elements S ₁ , S ₇ or S ₂ , S ₃ are operated according to their polarities H, L. In the figure, 20 is the current set value. , 21 indicates the hysteresis width, and 22 indicates the 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 when the polarity is negative (L), the switching elements S ₁ and S ₄ are operated, and When the polarity becomes positive (H), the switching elements S ₂ and S ₃ are operated and the positive or negative voltage is applied to the load including the current limiting reactor L ₀ to set the inverter load current to the set value 20. Make them follow.

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] In the present invention, in a single-phase current follow-up type inverter, two equivalent inverters are connected in series, switching of one of the inverters is determined according to the rate of change of the current set value, and the other By operating the inverter in accordance with the output of the hysteresis comparator, a mode for reducing the rate of change of the load current is created, the number of times of switching is reduced, and the capacity of this type of inverter device can be increased.

 The embodiment shown in FIG. 1 will be described below.

 The same parts as those in FIG. 2 are designated by the same reference numerals.

For the DC power source E ₁ , switching elements S ₁ and S ₃ are connected in series, and switching elements S ₂ and S ₄ are connected in series, and between the terminals of each of the switching elements S _{1 to} S ₄ for regeneration. first switching circuit iN diodes D ₁ to D ₄ each energization direction and energization direction of the switching elements S ₁ to S ₄ in the opposite
Forming a V1, another of the DC power source, with respect to E _2, the switching element S ₅ and S ₇ in series, connects the switching element S ₆ and S ₈ in series, each of the switching elements S ₅ to S ₈ Regenerative diodes D _{5 to} D ₈ are connected between the
S ₅ to the current direction and current direction to S ₈ in the opposite second switching circuit INV2 formed, between the connection point of the switching element S ₁ and the connection point between the switching element S ₆ and S ₈ of S ₃ A load 1 is connected via a current limiting reactor L ₀ that suppresses current change, and is connected at the connection point of switching elements S ₂ and S _{4 and} the connection point of switching elements S ₅ and S ₇ The switching circuits INV1 and INV2 are connected in series with the current limiting reactor L ₀ via the load 1 to form an inverter circuit. Here, the DC power supplies E ₁ and E ₂ may have the same size or different sizes.

Reference numeral 2 denotes an inverter load current detector, which is input to an error detector 3 which compares the current setting value to obtain an error, and the output side of the error detector 3 is connected to a hysteresis comparator 4 and a band comparator 8. Reference numeral 7 is an inverter load current polarity determiner, 6 is a current set value change rate detector, and the output side of the change rate detector 6 is connected to a band comparator 9.

The bandwidth of the band comparator 8 has a predetermined error current width wider than that of the hysteresis comparator 4, and the band comparator 9 has a predetermined change rate width.

The outputs of the band comparators 8 and 9 are input to the OR circuit 12, and the output side of the OR circuit 12 is input to the reset flip-flop circuit 10. This reset flip-flop circuit 10
Is also connected to the output side of the pulse generation circuit 11 connected to the output side of the hysteresis comparator 4.

The pulse generation circuit 11 outputs a pulse (H) when the output of the hysteresis comparator 4 changes. In the reset flip-flop circuit 10, when the S signal becomes H, Q = H, (=
L), and even if the S signal becomes L in this state, Q does not change, and if H is input to the Re signal in this state, Q = L, (
= H). Since the set value of the band comparator is set outside the hysteresis width, S signal = H and Re signal = H do not hold.

As shown in the figure, the output from the polarity determiner 7 is input to the AND circuit 13-1 together with the output of, and also input to the AND circuit 13-2 via the inversion circuit 5 together with the output.

The output side of the hysteresis comparator 4 is connected to the S ₁ amplifier and the S ₄ amplifier via the inverting circuit 5, and directly connected to the S ₃ amplifier and the S ₂ amplifier, and the hysteresis comparator 4 for the Q output signal and the S ₂ amplifier is used. The output signal is input to the S ₆ amplifier via the AND circuit 14-3, and the Q output signal and the output signal to the S ₄ amplifier are input to the S ₈ amplifier via the AND circuit 14-4.

Further, the Q output signal and the signal from the hysteresis comparator 4 for the S ₃ amplifier are input to the AND circuit 14-1, and the output side of the AND circuit 14-1 and the output side of the AND circuit 13-2 are connected to the OR circuit 15-2. The output side is connected to the S ₇ amplifier, and the Q output signal and the signal from the hysteresis comparator 4 for the S ₁ amplifier are input to the AND circuit 14-2,
The output side of the AND circuit 14-2 and the output side of the AND circuit 13-1 are connected to the OR circuit 15-1, and the output side thereof is connected to the S ₅ amplifier.

S ₁ amp to S ₈ amplifier it shall be closed during the switching elements S ₁ to S ₈ when there is an input thereto.

[Operation] small change rate of the set value, when the can sufficiently follow the current set value only INV1, INV2 the direction of the inverter load current (polarity) determining only the more the S _5, D ₆ or S _7, D ₈ Only S ₅ or S ₇ are turned on to form the reflux mode.

If the error becomes large or the rate of change of the error value becomes large, IN
The freewheeling mode based only on the polarity determination of the V2 inverter load current is stopped, and operation is performed according to the outputs of the band comparators 8 and 9. When the output of either of the band comparators 8 and 9 becomes H, the reset flip-flop circuit operates and Q = H, =
The output of gate B becomes L, the output of gate A becomes the same signal as the ON signal of INV1, and INV2 behaves similarly to INV1.

For simplicity of explanation, only INV1 has been mainly described, but the roles of INV2 and INV1 may be changed.

[Effect] As described above, according to the present invention, even when the rate of change of the current setting value is largely changed, each switching circuit is switched according to the rate of change. Therefore, the total number of switching times of the inverter circuit is reduced, From the aspects of switching loss, speed, etc., it is possible to increase the capacity of the inverter installation and improve followability.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention. FIG. 2 shows a conventional current tracking type inverter. FIG. 3 is an operation explanatory view of the inverter shown in FIG. 1 ... Load, 2 ... Current detector, 3 ... Error detector, 4
…… Hysteresis comparator, 8 …… Bandwidth comparator, 9 …… Set value change rate detector, 10 …… Reset flip-flop circuit, 11 …… Pulse generation circuit.

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 first switching circuit INV1 in which a circuit in which ₂ and S ₄ are connected in series are connected in parallel to a power source E ₁ and a switching element S ₅ and S _{7 in} which regenerative diodes D ₅ and D ₇ are connected in parallel are connected in series. Circuit connected to and diode D for regeneration
Switching elements S ₆ and S _{8 in} which ₆ and D ₈ are connected in parallel
Forming a second switching circuit INV2 in which a circuit in which is connected in series is connected in parallel to a power source E ₂ and
Current limiting reactor L ₀ and load 1 between the connection points of S ₁ and S ₃ , S ₆ and S ₈
An error detector that detects the error between the current setting value and the inverter load current value in the inverter load circuit formed by connecting the switching elements S ₂ and S ₄ , and S ₅ and S ₇ in series. 3, a rate-of-change detector 6 for detecting the rate of change of the current set value, and a polarity determiner 7 for the inverter load current are arranged, and the error current input to the output side of the error detector 3 is a predetermined error current. When it reaches the width, it is connected to the hysteresis comparator 4 which outputs the H signal or the L signal, and when it is larger than a predetermined error current width wider than the error current width of the hysteresis comparator, it is connected to the band comparator 8 which outputs the H signal, The output side of the change rate detector 6 is connected to a band comparator 9 which emits an H signal when it is larger than a predetermined change rate width, and the output sides of the band comparators 8 and 9 are connected via a core circuit 12. When the input signal to the OR circuit becomes H, the output terminal Q signal becomes H and the output terminal signal becomes L. When the output of the hysteresis comparator 4 changes, the output terminal Q signal becomes L and the output terminal signal becomes H. Is connected to the flip-flop circuit 10 having the function of, and the S ₁ amplifier and S ₄ amplifier for driving the switching elements S ₁ and S ₄ are provided from the hysteresis comparator 4 via inverting circuits 5-1 and 5-2, respectively. The S ₂ and S ₃ amplifiers for driving S ₂ and S ₃ are the hysteresis comparator 4 with all output signals.
Is driven at a output signal, driving S ₅ amplifier of the switching element S ₅ is the AND circuit 13-1 inputs the output signal of the output signal and the flip-flop circuit 10 of the polarity detector 7 of the load current An AND circuit 14-2 receives the output signal, the output signal from the hysteresis comparator 4 to the S ₁ amplifier via the inverting circuit 5-1 and the output terminal Q signal of the flip-flop circuit 10.
Is inputted to the OR circuit 15-1 and driven by the output signal, the driving S ₇ amplifier of the switching element S ₇ outputs from the load current polarity judging device 7 through the inverting circuit 5-3. A signal and the output signal of the flip-flop circuit 10, the output signal of the AND circuit 13-2, the output signal from the hysteresis comparator 4 to the S ₃ amplifier, and the output signal Q of the flip-flop circuit 10. The input signal of the AND circuit 14-1 is input to the OR circuit 15-2 and is driven by the output signal. The driving amplifier of the switching element S ₆ is the hysteresis comparator 4 to the S ₂ amplifier. Driven by the output signal of the AND circuit 14-3 which receives the output signal of the flip-flop circuit 10 and the output signal of the flip-flop circuit 10, and the S ₈ amplifier for driving the switching element S ₈ is the hysteresis to the S ₄ amplifier. Inversion circuit 5
A current tracking type inverter characterized in that it is driven by the output signal of 2 and the output signal of an AND circuit 14-4 which receives the output Q signal of the flip-flop circuit 10.