JPH0487572A - Power unit - Google Patents

Abstract

PURPOSE:To obtain a power unit having high control-accuracy and high efficiency by coarsely adjusting voltage variations caused by load variations with large-capacity 3-phase rectangular wave inverters, and by finely adjusting with small-capacity single-phase PWM sine-wave inverters at every phase. CONSTITUTION:Each phase output of large-capacity 3-phase rectangular wave inverters 5a, 5b is connected with the outputs of three small-capacity single- phase PWM sine-wave inverters 12a-12c in series respectively. By this constitution, composite voltages of the output voltages of 3-phase rectangular wave inverters 5a, 5b and those of three single-phase PWM sine-wave inverters 12a-12c added in series at every phase are applied to a load. On this occasion, voltage variations caused by load variations are adjusted coarsely by the large-capacity 3-phase rectangular wave inverters 5a, 5b, and adjusted finely by the small- capacity single-phase PWM sine-wave inverters 12a-12c at every phase.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a power supply device for a 400 Hz or high frequency (about several hundred Hz) power distribution system used, for example, to supply power to parked aircraft at an airport. It is something.

[Conventional technology]

For example, the power distribution inside an aircraft is - Frequency 400H for boat fishing.
z, a three-phase four-wire wiring system with a phase voltage of 115V and a line voltage of 200V. On the other hand, the loads inside the aircraft include three-phase loads such as motors, and single-phase loads such as lighting equipment. Each load is connected to one of the three-phase, four-wire wiring as appropriate, and the loads are It is often unbalanced.

The power supply equipment that supplies power to the loads in the three-phase, four-wire distribution system described above requires voltage adjustment for each phase to maintain each phase voltage at a specified value, so a three-phase inverter that can be used on a boat is used. However, it is configured using three single-phase inverters. Such a conventional example is shown in FIG. In FIG. 6, 51 is a three-phase AC power source at a commercial frequency, 52 is a rectifier that rectifies the voltage of the three-phase AC power source 51, and 53 is a DC filter made of an electrolytic capacitor and removes ripple components. 54a to 54c are single-phase PWM sine wave inverters, respectively, between output terminals u and x, and v.

A single-phase sine wave voltage of 400 Hz is generated between Question 7, W, and 2, respectively. 55a to 55c are single-phase transformers, and 56a to 56C are filters for removing switching frequency components. 57a to 57c are A phase, B phase,
Each C-phase power supply terminal 57n is a neutral (N) phase power supply terminal, and a load (not shown) is connected to each power supply terminal 57a to 57c, 57n.

The power supply device configured as described above converts the DC voltage obtained by the rectifier 52 and the DC filter 53 into three single-phase P
400Hz with 3-phase 4-wire wiring by WM sine wave inverters 54a to 54C and three single-phase transformers 55a to 55C
It will be converted into a high frequency voltage. At this time, the switching frequency components appearing on the secondary side of the single-phase transformers 55a to 55C are removed by the switching frequency component removal filters 56a to 56c made of capacitors, and the voltage waveform between the power supply terminals 57a to 57C157n becomes a sine wave. .

In this case, the phase voltage of each phase is set to, for example, 115V, that is, the line voltage is set to 200V.

The above single-phase PWM sine wave inverters 54a to 54c are
In both cases, pulse width modulation (PWM) control is performed to switch a power semiconductor switching element (for example, an insulated gate bipolar transistor, etc.) at a high frequency of 10 KHz or higher in order to bring the output voltage close to a sine wave. The switching frequency components are removed by the switching frequency component removal filters 562 to 56c.

FIG. 7 shows a circuit example of single-phase PWM sine wave inverters 542 to 54C, in which Q, to Q, and 4 are insulated gate bipolar transistors, and DI+-'-DI4 is a diode.

For example, the PW in the single-phase PWM sine wave inverter 54a
The M control compares the magnitude of the target voltage VIIIF having a sinusoidal waveform as shown in FIG. By controlling, a voltage including a switching frequency component as shown in FIG. 8 (bl) can be obtained as the inverter output, that is, the input voltage to the single-phase transformer 55a. 56a
The switching frequency component is removed, and a sine wave voltage as shown in FIG. 8 (C1) is obtained as the secondary voltage of the single-phase transformer 55a.

By detecting the voltage of each phase and changing the amplitude of the target voltage V ltF according to the detection result, the voltage of each phase applied to the load can be maintained constant regardless of load fluctuations.

[Problem to be solved by the invention]

When the power semiconductor switching elements that make up the inverter perform a switching operation, a loss called a switching loss occurs, and this loss increases as the switching frequency becomes higher.

Therefore, as in the conventional example shown in FIG. 6, when the power semiconductor switching elements constituting the full-rated single-phase PWM sine wave inverters 541 to 54c are switched at a high frequency of about 10 KHz or higher, the power semiconductor switching elements 543 to 54c Since the switching loss of the single-phase PWM sine wave inverters 543 to 54c is large, the operating loss of the single-phase PWM sine wave inverters 543 to 54c increases, and the efficiency as a power supply device becomes less than 90%, which is not preferable.

On the other hand, a rectangular wave inverter can also be considered as an inverter, but since this rectangular wave inverter has low control accuracy,
Not suitable for the above uses.

An object of the present invention is to provide a power supply device with high control accuracy and high efficiency.

[Means to solve the problem]

The power supply device of the present invention connects the outputs of three small-capacity single-phase PWM sine wave inverters in series to the outputs of each phase of a large-capacity three-phase rectangular wave inverter, and The voltage applied to the load is roughly controlled, and the single-phase PWM
The voltage applied to the load is finely controlled for each phase using a sine wave inverter.

[For production]

According to the configuration of the present invention, a composite voltage obtained by applying the output voltage of each phase of the three-phase square wave inverter and the output voltage of three single-phase PWM sine wave inverters in series to each phase is applied to the load. become. At this time, the voltage fluctuation due to load fluctuation is
Coarse adjustment is performed using a large-capacity three-phase square wave inverter, and fine adjustment is performed for each phase using a small-capacity single-phase PWM sine wave inverter.

In this way, by performing coarse adjustment with a large-capacity three-phase rectangular wave inverter and fine-tuning each phase with a small-capacity single-phase PWM sine wave inverter, the voltage applied to the load can be adjusted with high precision for each phase. can be controlled.

Moreover, most of the voltage applied to the load is provided by a three-phase rectangular wave inverter, and a small capacity single-phase PWM sine wave inverter is used to compensate for small fluctuations in each phase due to load fluctuations. Even if the operating loss of a large-capacity single-phase PWM sine wave inverter is large, the operating loss of a large-capacity three-phase rectangular wave inverter is small, so the overall efficiency can be made sufficiently high.

〔Example〕

An embodiment of the present invention will be described based on FIGS. 1 to 5. As shown in FIG. 1, this power supply device includes a large capacity three-phase rectangular wave inverter 5a.

The outputs of three small-capacity single-phase PWM sine wave inverters 12a to 12C are connected in series to the output of each phase of 5b, respectively.
The three-phase rectangular wave inverters 5a and 5b roughly control the voltage applied to the load, and the single-phase PWM sine wave inverters 12a to 12c
The voltage applied to the load is finely controlled for each phase.

With this configuration, the three-phase rectangular wave inverters 5a, 5
b output voltage and three single-phase PWM sine wave inverters 12
A composite voltage obtained by adding the output voltages of a to 12c in series for each phase is applied to the load. At this time, voltage fluctuations due to load fluctuations are handled by a large-capacity three-phase rectangular wave inverter 5a,
5b, and fine adjustment is performed for each phase by small-capacity single-phase PWM sine wave inverters 12a-12c.

The power supply device of this embodiment will be explained in detail below.

As shown in Fig. 1, this power supply device consists of two three-phase AC power
0 voltage is subjected to three-phase full-wave rectification by a thyristor rectifier 2 via a three-phase input transformer 1, and the ripple component is removed by a ripple removal reactor 3 and a ripple removal capacitor 4, resulting in two three-phase intelligent waves. Power is supplied to inverters 5a and 5b.

These three-phase rectangular wave inverters 5a, 5b, for example, as shown in FIG. Diode D + connected in antiparallel to Q.
”= D & each switching element Q1
~Q, is turned on and off at a predetermined timing to output a three-phase rectangular wave voltage of, for example, 4001 (z) whose phase is shifted by 120 degrees from the midpoint of each of the three series circuits. The output adjustment is performed by controlling the firing angle of the thyristor of the thyristor rectifier 2 in the previous stage to increase or decrease the DC voltage applied to the three-phase rectangular wave inverters 5a and 5b.The capacity is, for example, when the load rating is 100 K va. , the output capacity of the three-phase rectangular wave inverters 5a and 5b is also set to the same capacity of 100 K v^.

The outputs of the three-phase square wave inverters 5a, 5b are applied to multiplexing transformers 6a, 6b. In this case, multiplexing transformer 6b
performs Δ-Y conversion, and the multiplexing transformer 6a employs a staggered winding to perform Δ-open Δ conversion, adding the secondary voltages of both multiplexing transformers 6a and 6b in series. The combined voltage is as shown in FIG. 3 (ta), for example. With this configuration, the harmonic content can be minimized.

The combined voltage of the secondary voltages of the multiplexing transformers 6a and 6b is:
Harmonic components are removed by filter capacitors 73 to 7c, and the waveform of each phase becomes a sine waveform, which is connected in series with the output voltage of single-phase PWM sine wave inverters 12a to 12c, which will be described later, by series compensation transformers 16a to 16c. Electricity is applied and output from the output cables 21a to 21c and 2In.

In addition, this power supply device performs three-phase full-wave rectification of the voltage of a three-phase AC power supply 20 via a three-phase input transformer 8 with a diode rectifier 9, and removes ripples with a ripple removal reactor 10 and a ripple removal capacitor 11. The components are removed and power is supplied to three single-phase PWM sine wave inverters 12a-12c.

These single-phase PWM sine wave inverters 128 to 12C turn on/off switching elements based on the comparison result between a target voltage consisting of a three-phase sine wave of 400 Hz, for example, and a triangular wave voltage with a frequency of about 10 KHz, which is a carrier voltage. By doing so, a sine wave voltage (including a carrier wave component) as shown in, for example, the third equivalent corresponding to the target voltage
This outputs the following.

The capacity of this single-phase PWM sine wave inverter 122~12c is, for example, 6~12c when the load rating is 100KV^ mentioned above.
It is set to about 10KV^.

Each output voltage of each of the above-mentioned single-phase PWM sine wave inverters 12a to 12c is converted to a series compensation transformer 162 to 16c after carrier components are removed by filter reactors 13a to 13C and filter capacitors 14a to 14C.
is added in series with the summed voltage of the three-phase rectangular wave inverters 5a and 5b mentioned above through the output cables 21a to 21a.
It will be output from 21C and 21rl. The voltage output from the output cables 212 to 21C21n and applied to the load is, for example, 40V as shown in FIG. 3(C).
It becomes a 0Hz sine wave.

In this case, the phase voltage and line voltage are, for example, 115V,
It is set to 200V.

Bypass switches 158 to 15C that short-circuit the primary sides of series compensation transformers 162 to 16c are activated when a failure occurs in any of the circuit parts from input transformer 8 to filter reactors 132 to 13C and filter capacitors 148 to 14C. When the single-phase PWM sine wave inverter 128~12C is no longer able to generate a sine wave voltage
By shorting the output side of the three-phase rectangular wave inverter 5a, 5
b is provided to continue supplying power to the load by itself.

The above-mentioned thyristor rectifier 2, 3-phase square wave inverter 5
a, 5b and single phase PWM sine wave inverter 12a~1
2c is controlled by the control circuit 19. In this case, the control circuit 19 controls the voltage detection transformers 17a to 17.
C detects the output voltage VSA+vSl+VSC of each phase of the three-phase rectangular wave inverters 5a, 5b, and current detection current transformers 18a to 18C detect the output current of each phase of the three-phase rectangular wave inverters 5a, 5b. I LAI I Lm
, I LC is detected, and based on the detected voltage and current, the thyristor rectifier 2, three-phase square wave inverter 5a
, 5b and single-phase PWM sine wave inverters 12a-12
c.

Note that 22 is a voltage detection resistor, 23 is a current detection current transformer, and 243 to 24C are current detection current transformers.

Here, three-phase rectangular wave inverters 5a, 5b and single-phase P
The control circuit for the WM sine wave inverters 12a-12c will be explained based on FIGS. 4 and 5.

First, the control of the three-phase rectangular wave inverters 5a and 5b will be explained with reference to FIG.

In the control circuit of FIG. 4, a three-phase rectangular wave inverter 5a
, 5b, the output voltage of each phase V 3A, V 5@.

VSC is detected by voltage detection transformers 17a to 17c, and their secondary voltages are full-wave rectified by rectifiers 318 to 31C, respectively, and added by an adder 34. On the other hand, the output voltage a I tA of each phase of the three-phase rectangular wave inverters 5a and 5b.

111+ I Lc as current detection current transformer 182 to 18
C and detect those secondary currents through the output cables 218 to 218.
The impedance simulation circuits 328 to 32c that simulate the impedance of 21C convert it to voltage, and the voltage of each impedance simulation circuit 328 to 32C is converted to a voltage by the rectifiers 338 to 33C.
They are each subjected to full-wave rectification and added by an adder 35.

The voltage of the impedance simulation circuits 322 to 32c is
Output current I of each phase in output cables 218 to 21C
LAI I Lm, corresponds to the voltage drop due to I LC.

Then, the output of the adder 35 is subtracted by the subtracter 36 from the output of the adder 34, and the result is multiplied by a coefficient of 1/3 in the coefficient unit 37. As a result, the average value of the voltages obtained by subtracting the voltage drops due to the output cables 218 to 21C from the output voltages VSA and VSL+Vsc of each phase is obtained as the output of the coefficient unit 37.

Furthermore, the subtracter 39 subtracts the output of the coefficient multiplier 37 from the reference value output from the reference value generator 38 (for example, a value corresponding to the phase voltage 115■) to find the difference between the two. The gate pulse generation circuit 40 compares the difference amplified by the error amplifier 39A and the sawtooth wave voltage, and a gate pulse is applied to each sirisk of the sirisk rectifier 2 at a timing according to the comparison result.

By controlling the firing angle of the thyristor of the thyristor rectifier 2 using the control circuit as described above, the average value of the voltage applied to the load is controlled to be constant.

At this time, since it is not possible to correct the unbalance of each phase voltage during a single-phase load, the correction is performed using single-phase PWM sine wave inverters 12a to 12c, which will be described below.

Next, control of the single-phase PWM sine wave inverters 12a to 12c will be explained with reference to FIG. Note that since each phase is controlled in the same way, control of the single-phase PWM sine wave inverter 12a corresponding to the A phase will be explained as an example.

In the control circuit of FIG. 5, a three-phase rectangular wave inverter 5a
The A-phase output voltage VSA of the three-phase rectangular wave inverters 5a and 5b is detected by the voltage detection transformer 17a, and is added to the synchronization circuit 41 to generate a synchronization signal synchronized with the A-phase output voltage VSa of the three-phase rectangular wave inverters 5a and 5b. Based on this synchronization signal, a reference amplitude sine wave generation circuit 42 generates a 400 Hz sine wave signal with a reference amplitude. In this case, the reference amplitude sine wave generation circuit 42 is
For example, it includes a counter that counts a clock signal that is an integral multiple of a synchronization signal, and a read-only memory that stores sine waveform data and is accessed using the output value of the counter as an address.

Then, the subtracter 43 calculates the error voltage ε between the sine wave signal and the voltage corresponding to the A-phase output voltage VSa. Further, the adder 44 adds this error voltage ε and the voltage drop z-ILA due to the output cable 21a for the A phase to obtain the target voltage VIII! Creating F.

In the above, in controlling the single-phase PWM sine wave inverter 12a, the voltage drop Z'lLA due to the A-phase output cable 21a is subtracted from the error voltage ε.
This is because, in controlling the three-phase rectangular wave inverters 5a and 5b, voltage correction is performed based on the average value of cable voltage drops.

Then, the target voltage v+tzr and the carrier wave voltage VC consisting of a triangular wave are compared by the comparator 45, and a gate pulse is generated as well-known at a timing according to the comparison result, and this gate pulse is applied to the single-phase PWM sine wave inverter 12a. By adding , a voltage having a waveform as shown in FIG. 3 (bl) is outputted from the single-phase PWM sine wave inverter 12a.

The carrier wave component of the voltage outputted from the single-phase PWM sine wave inverter 12a as shown in FIG. 3(b) is removed by the filtering reactor 13a and the filtering capacitor 14a, resulting in a smooth sine wave. .

By controlling the on/off of the switching elements of the single-phase PWM sine wave inverters 12a to 12c using the control circuit as described above, the single-phase PWM sine wave inverter 12
The output voltages of a to 12c are individually controlled, and as a result, the voltage of each phase applied to the load is individually controlled to be constant.

Although not shown, the control circuit 19 is a circuit that controls the switching of the three-phase rectangular wave inverters 53 to 5b, and a circuit that controls the switching of the single-phase PWM sine wave inverters 12a to 12C based on fluctuations in the DC voltage applied to the single-phase PWM sine wave inverters 12a to 12C. It also includes a circuit for correcting the outputs of the phase PWM sine wave inverters 12a to 12c.

In the power supply device of this embodiment, coarse adjustment is performed by three-phase rectangular wave inverters 5a and 5b with large capacity and low control accuracy, and fine adjustment for each phase is performed by a single-phase PWM sine wave inverter 12a with small capacity and high control accuracy. By performing this at ~12C, the voltage applied to the load can be controlled with high precision for each phase.

Moreover, most of the voltage applied to the load is applied to the three-phase rectangular wave inverter 5a, 5 with high efficiency (can be increased to 95% or more).
b, and the correction for small fluctuations due to voltage fluctuations is supplied from small-capacity, low-efficiency (about 85%) single-phase PWM sine wave inverters 12a to 12c. Sine wave inverters 12a to 12c
However, since the operation loss of the large-capacity three-phase rectangular wave inverters 5a and 5b is small, the overall efficiency can be made sufficiently high.

Moreover, since two rectangular wave inverters 5a and 5b are combined, the square wave inverter 5a.

The harmonics generated from 5b can be reduced and removed easily.

In the above embodiment, the present invention is applied to a ground power source for an aircraft, but the present invention is not limited to this, and can also be applied to high frequency power distribution in buildings, etc., and the power source frequency is not limited to 400K.

(Effects of the Invention) According to the power supply device of the present invention, coarse adjustment is performed using a large capacity three-phase rectangular wave inverter, and m!IN adjustment for each phase is performed using three small capacity single phase PWM sine wave inverters. By doing this, it is possible to control the voltage applied to the load with high precision for each phase.Moreover, most of the voltage applied to the load is covered by the 3-phase square wave inverter, and the correction for small fluctuations due to voltage fluctuations is is covered by a small-capacity single-phase PWM sine wave inverter, and even if the operating loss of a small-capacity single-phase PWM sine-wave inverter is large, the operating loss of a large-capacity three-phase rectangular wave inverter is small, so the overall The efficiency can be made sufficiently high.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing the configuration of a power supply device according to an embodiment of the present invention, FIG. 2 is a circuit diagram showing the basic configuration of a three-phase rectangular wave inverter, and FIG. 3 is a waveform of each part of the circuit in FIG. 1. Figure 4 is a block diagram showing the configuration of the circuit portion that controls the thyristor rectifier in the control circuit, and Figure 5 is the configuration of the circuit portion that controls the single-phase PWM sine wave inverter of the 48 circuits. 6 is a circuit diagram showing the configuration of a conventional example of a power supply device, FIG. 7 is a circuit diagram showing the basic configuration of a single-phase PWM sine wave inverter, and FIG. 8 is a waveform of each part in FIG. 7. It is a diagram. 2... Thyristor rectifier, 3... Ripple removal reactor, 4... Ripple removal capacitor, 5a5
b... Three-phase square wave inverter, 6a, 6b... Multiplexing transformer, 72-7c... Filter capacitor, 1
0... Reactor for ripple removal, 11... Capacitor for ripple removal, 12a-12c... Single phase PWM
Sine wave inverter, 13a-13c... Filter reactor, 14a-14c... Filter capacitor, 15... Bypass switch, 16a-16c...
Series compensation transformer, 19...control circuit, 2o...3
Phase AC power supply patent applicant Japan Airport Power Co., Ltd.

Claims (1)

[Claims] The output of each phase of a large-capacity three-phase square wave inverter and the output of three small-capacity single-phase PWM sine wave inverters are each coupled in series, and the voltage applied to the load by the three-phase square wave inverter is roughly calculated. A power supply device in which the voltage applied to the load by the single-phase PWM sine wave inverter is finely controlled for each phase.