JP2517926B2 - 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. 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 S ₁
Current limiting reactor L ₀ that suppresses current change by connecting point of S ₃
Is connected to one end of the load 1, 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.

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
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. 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 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] The present invention relates to an inverter circuit in which a switching circuit including a power supply having different DC voltage values is connected in series via a current limiting reactor and a load in a single-phase hysteresis comparator type current follow-up inverter. , Switching is decided so that the sum or difference of the DC voltage is applied to the load according to the change rate of the current set value, and the number of times of switching is reduced while satisfying the high-speed followability, thereby enabling a large capacity. Is.

 The present invention will be described below with reference to an 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 to the DC power source E ₁ , and switching elements S ₂ and S ₄ are connected in series, and a regeneration diode is provided between the terminals of each of the switching elements S _{1 to} S _4. D ₁ to D ₄ respectively connected to the energized direction flowing direction of the switching device in the reverse form the switching circuit, also the DC becomes possible voltage from another DC power source E ₁ power E ₂
Hand, the switching element S ₅ and S ₇ in series, connects the switching element S ₆ and S ₇ in series, the switching element S ₅
The regenerative diode D ₅ to D ₈ respectively connected to the energized direction flowing direction of the switching element in reverse to form a switching circuit between each of the terminals to S _6, the switching element S ₁
Load through the suppressing current limiting reactor L ₀ connection change between the connection point of the connection point of the switching element S ₆ and S ₈ of S ₃ 1 is connected to, also, connection of the switching element S ₂ and S ₄ The point and the connection point of the switching elements S ₅ and S ₇ are connected, and switching circuits I and II for the power supplies having two different DC values are connected in series via the current limiting reactor L ₀ and the load 1, and the inverter circuit is connected. Form.

Reference numeral 2 is an inverter load current detector, which is input to an error detector 3 for comparison with a current set value, and the output side thereof judges the error signal with H ₁ and L ₁ with a predetermined hysteresis width. With a hysteresis rape of 1, if the increase or decrease of the error signal further increases after the judgment, with a predetermined hysteresis width
It is connected to a hysteresis comparator 7 having a second hysteresis loop for judging H ₂ and L ₂ .

The output side of this hysteresis comparator 7 is directly connected to S3
S1AMP, S4A connected to AMP, S2AMP and via inverting circuit 5
It is connected to MP, and S5AMP, S8AM by the interlock changeover switch 8.
When P is connected to the hysteresis comparator 7, S
7AMP and S6AMP are connected through the inverting circuit 5, and S5AMP and S8AM
When P is connected through the inverting circuit 5, S7AMP, S6AMP
Are switched so that they can be directly connected to the output side of the hysteresis comparator 7.

As already mentioned, the power supplies E ₁ and E ₂ have different voltage values,
The smaller value is the power source that can be regenerated.

[Operation] If the load current change rate of the inverter is set so as to follow the maximum change rate when the change rate of the current set value changes significantly, the number of times of switching increases when the current setting waveform is flat. For this reason, the load current change rate of the inverter is reduced in the flat portion of the current setting waveform.

Connected in series through a current limiting Akutoru L ₀ and the load 1 to the switching circuit I comprises a power E ₁ a switching circuit 11 having a power E ₂ different DC voltage value of the supply E _1, typically both switching circuits The polarities of the I and II output voltages are different. If the rate of change of the set value is small, this E ₁
Hysteresis operation is performed so as to follow the current setting value by the voltage of the difference of E ₂ .

When the change rate of the current setting value becomes large, the inverter current cannot follow up, the error becomes large and the second hysteresis loop operates, the output voltage polarity of the switching circuit changes, and the voltage of the sum of E ₁ and E ₂ becomes the load. 1 and current limiting reactor
Applied to L ₀ , the current change rate becomes larger than before and follows the set value.

The operation will be specifically described according to the current set value in FIG. In the figure, 20 indicates a current setting value.

In the figure, a indicates a portion where the change in the set current value is small, b indicates a portion where the change in the set current value is large, 21 indicates the first hysteresis width, and 22 and 22 'indicate the second hysteresis loop. Hysteresis width, the upper hysteresis width is installed so that it is above and below the upper limit H ₁ of the first hysteresis loop, and the lower hysteresis width 22 'is the first
It is installed so that it is above and below the lower limit L ₁ of the hysteresis loop of.

The part a shows the operation within the range of the first hysteresis loop. By reaching L ₁ of the first hysteresis loop, the switching elements S ₁ and S ₄ are turned on and S ₆ and S ₇ are turned on, so that the current rises due to the difference voltage between the power sources E ₁ and E ₂ , for example, In FIG. 2C, the upper limit H ₁ of the first hysteresis loop is reached,
The switching elements S ₂ , S ₃ , S ₅ , S ₈ are turned on, and the inverter load current drops. As indicated by the point d, when the inverter load current reaches the upper limit H ₂ of the second hysteresis loop, S ₆ and S ₇ are turned on by the changeover switch 8 while the switching elements S ₂ and S ₃ are on. , Power supplies E ₁ and E ₂ are added,
It causes a rapid drop and responds to large changes in current setpoint. As shown by the point d in the inverter load current value,
The second within the hysteresis width 21 of the hysteresis loop of
Reaching the upper and lower limit e of the hysteresis loop of, the changeover switch 8 is changed over, the switching elements S ₂ and S ₃ are turned on, S ₅ and S ₈ are turned on, and the inverter load currents are the power supplies E ₁ and E _2. A differential voltage of 1 flows through the load 1 and the current limiting reactor L ₀ .

When the current setting value suddenly rises and the error signal reaches the lower limit L ₂ of the second hysteresis loop, the switching elements S ₁ , S
_{When 4} is on, S ₅ and S ₈ are turned on by the interlock changeover switch 8 and the sum of the power supplies E ₁ and E ₂ flows to the load 1 and the current limiting reactor L ₀ , causing the inverter load current to rise sharply and set To follow.

[Effects] As described above, the present invention provides a hysteresis comparator type current follow-up type inverter that improves current follow-up when the rate of change of the set current is large and does not unnecessarily increase the number of times of switching even when the rate of change is small. realizable.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention. FIG. 2 is an operation explanatory diagram of the present invention. FIG. 3 shows an example of a conventional hysteresis comparator type current tracking type inverter. FIG. 4 is an operation explanatory view of the inverter shown in FIG. 1 ... Load, 2 ... Inverter load current detector, 3 ...
Error detector, 5 ... polarity reversing circuit, 7 ... hysteresis comparator, 8 ... interlocking selector switch.

Claims (1)

(57) [Claims] 1. A regenerative diode in parallel with a DC power source E _1.
Switching elements S ₁ and S _{3 in} which D ₁ and D ₃ are connected in parallel
Is connected in series with a circuit in which switching elements S ₂ and S _{4 in} which regenerative diodes D ₂ and D ₄ are respectively connected in parallel are connected, and the power source E _1. A circuit in which switching elements S ₅ and S _{7 in} which regeneration diodes D ₅ and D ₇ are respectively connected in parallel are connected in series to a DC power source E ₂ of different voltage and regeneration diode D ₆ and
A second switching circuit in which a circuit in which switching elements S ₆ and S _{8 in} which D ₈ are respectively connected in parallel are connected is connected to a connection point of the switching elements S ₁ and S ₃ and switching elements S ₆ and S ₈ Current limiting acrylic resin L ₀ and load 1 between the connection points
An error detector for detecting an error between a current setting value and a load current value in an inverter circuit in which the connecting points of the switching elements S ₂ and S _{4 and} the connecting points of the switching elements S ₅ and S ₇ are connected in series. 3 and an error signal from the detector as an input, the upper limit H _{1 of} the signal with a first predetermined hysteresis width,
Or, if the increase / decrease of the error signal expands even after the first hysteresis loop for judging the lower limit L ₁ and the judgment of the error signal, the upper limit H ₂ of the signal or the lower limit of the second predetermined hysteresis width
A _second hysteresis loop for determining L ₂ , and when the error signal returns from the second hysteresis width region to the first hysteresis width region, the first hysteresis width upper limit H ₁ and comprising a hysteresis comparator 7 determines the lower limit L _1, the switching element S _1, S ₄ side via the polarity inversion circuit 5, the S _2, S ₃ side is connected to the output side of the direct hysteresis comparator 7, the switching element S ₅ , S
_6, S _7, the interlocking switch 8 between the S ₈ side to the output side of the hysteresis comparator 7, the switching element S _5, S
_{When the 8} side is directly connected to the output side of the hysteresis comparator 7, the S ₆ and S ₇ sides are connected to the output side of the hysteresis comparator 7 via the polarity inverting circuit 5, and the S ₅ and S ₈ sides are connected to the polarity inverting circuit 5 when connected to the output side of the hysteresis comparator 7 via, S _6, S ₇ side is formed so as to be connected to the direct output side of the hysteresis comparator 7, current, characterized by the following sequence of operations Follow-up inverter. a: When the error signal reaches the lower limit L ₁ of the first hysteresis loop, the switching elements S ₁ , S ₄ , S ₆ , S ₇ are turned on and the other switching elements are turned off. b: When the error signal reaches the upper limit H ₁ of the first hysteresis loop, the switching elements S ₂ , S ₃ , S ₅ , S ₈ are turned on, and the other switching elements are turned off. c: When the error signal reaches the upper limit H ₂ of the second hysteresis loop, the switching elements S ₂ and S ₃ are turned on, and the interlocking selector switch 8 turns on S ₆ and S ₇ , and the other switching elements. Turns off. d: When the error signal reaches the lower limit L ₂ of the second hysteresis loop, the switching elements S ₁ and S ₄ are turned on, and the interlocking changeover switch 8 turns on S ₅ and S ₈ , and the other switching elements Turns off.