JPH06284742A - Inverter equipped with battery charging function - Google Patents

Abstract

PURPOSE:To take out a controlled DC output for battery charging simultaneously while an AC output is being taken out by a method wherein, when a battery is charged, an offset voltage is added to each phase voltage instruction. CONSTITUTION:A capacitor 7 for an inverter 5 is formed as divided capacitors 7A, 7B, and a neutral point for a generator 4 is connected to a dividing point A. A reactor 20 equipped with a center tap 21 is connected between U-phase and V-phase output terminals U, V for the inverter 5. The positive pole of a battery 10 is connected to the center tap 21. The negative pole is connected to the connection point A for the capacitors 7A, 7B via a switch 22a for charging, and it is connected to the negative pole N of an inverter DC bus via a switch 22b for a starter. In a charging operation, the switch 22a is turned on, and a charging-voltage instruction V*B which is output by a deviation amplifier 42 amplifying the deviation of a charging-current instruction I* from the output of a current sensor 43 is added to U-phase and V-phase voltage instructions V*U, V*V=.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter having a battery charging function.

[0002]

2. Description of the Related Art FIG. 4 shows the structure of a conventional portable engine-type power generator. In the figure, 1
Is a fuel tank, 2 is a fuel supply device (injector), 3
Is a gas turbine engine (hereinafter, simply referred to as engine) E, 4 is a magnet type three-phase synchronous generator (hereinafter, simply referred to as generator) SG, and 5 is a power converter. The AC output of this power converter 5 is the reactor Lo and the capacitor C.
It is output through a smoothing circuit consisting of o. The power conversion device 5 includes a forward conversion unit 6, an electrolytic capacitor 7, and a reverse conversion unit 8. 9u and 9w are output terminals.

The generator 4 has a main winding 4P on the high voltage side and an auxiliary winding 4S on the low voltage side, and the main winding 4P is connected to a power converter (inverter) 5. The electric power generated by the auxiliary winding 4S is used as electric power for auxiliary equipment such as the fan and the fuel supply device 2. The generated voltage of the main winding 4P is Vp. Auxiliary winding 4
The generated voltage Vs of S is taken into the rotation speed detector 20 and is used to detect the rotation speed of the generator 4. The detected rotation speed N is compared with the rotation speed command N ^* , the deviation thereof is given to the fuel supply device 2 through the deviation amplifier 21, and the fuel supply device 2 is controlled so as to eliminate the deviation.

The forward conversion section 6 has six transistors Q _{1 to} Q ₆ which are bridge-connected as shown in FIG. 5, and diodes D _{1 to} D ₆ which are respectively connected in antiparallel to each other.
The inverse conversion unit 8 is a single-phase bridge circuit including four transistors T _{r1 to} T _r4 connected in a bridge and four diodes D _{7 to} D ₁₀ connected in anti-parallel to each of the transistors.

Reference numeral 10 denotes a battery for an engine starter having a nominal voltage of 12 or 24 volts, which is connected between a positive electrode P and a negative electrode N of a DC circuit of the inverter 5 via a step-down circuit (step-down chopper circuit) 11. There is. 10A
Indicates the internal resistance r of the battery 10, and 10B indicates the battery voltage V _BT . The step-down chopper circuit 11 is a chopper element 1
2, a reactor 13 and a diode 14 are provided. 1
A charge control circuit 5 compares the charging current I _B detected by the current sensor 16 with the charging current command value I _B ^* and amplifies the deviation, and a PWM signal generator 18 for generating a PWM signal. The PWM signal is applied to the base of the chopper element 12 via the switch 19 to control the chopper element 12. The switch 19 is opened except when charging the battery.

In this apparatus, when the engine 3 is started, the switch SW is closed, the battery 10 is connected to the output circuit of the inverter 5, and one of the transistors, one of the diodes, and the filter circuit that constitute the inverse conversion unit 8 are connected. The reactor is used to form a booster circuit, which boosts the voltage of the battery 10 and causes the forward conversion unit 6 to perform a reverse conversion operation to operate the generator 4 as a motor.

After the start of the engine 3 is completed, the battery 10 is charged by operating the step-down circuit (step-down chopper circuit) 11 by opening the switch SW.

[0008]

Since this type of portable engine-type power generator is required to be as inexpensive as possible, the number of parts can be reduced as much as possible and inexpensive parts can be used. However, in the case where the charging power is obtained from the inverter 5 as described above, a circuit (battery charger) for exclusive use of battery charging, which includes a step-down circuit (step-down chopper circuit) 11 and its control circuit 15, is provided. The ratio of the charging circuit portion to the cost of the circuit device becomes large, which is a bottleneck for cost reduction. The present invention has been made to solve this problem, it is not necessary to provide a dedicated circuit for charging the battery (battery charger), it is possible to further miniaturize the device including a battery for the engine starter, Another object of the present invention is to provide an inverter with a battery charging function that can reduce costs.

[0009]

In order to achieve the above object, the present invention provides an inverter having a switching element bridge-connected, wherein a reactor with a center tap is connected between output terminals and the center tap is connected. A battery is connected between the center tap of the attached reactor and the intermediate potential of the inverter DC circuit via a battery charging switch, and the offset voltage is added to the voltage command for each phase of the inverter control circuit during battery charging. And In the present invention, the battery is a battery for an engine starter, the inverter is connected to the generator connected to the engine, and the negative electrode of the battery is connected to the negative electrode of the inverter DC circuit through the starter switch. It was configured.

According to another aspect of the present invention, the inverter is a single-phase inverter, and the control circuit thereof has a circuit for generating a U-phase voltage command and a V-phase voltage command, a carrier signal, a U-phase voltage command and a V-phase voltage command, respectively. A U-phase PWM signal generation circuit and a V-phase PWM signal generation circuit to be compared, a driver for applying the output of the U-phase PWM signal generation circuit and an inverted signal of the output to the positive and negative switching elements of the U-phase arm of the inverter, and the V-phase PWM signal generation A driver for applying an output of the circuit and an inverted signal of the output to the positive and negative switching elements of the V-phase arm of the inverter, and a circuit for calculating a deviation between the battery charging current and the battery charging command value and outputting a charging voltage command, The charging voltage command is added as an offset voltage to the voltage command of each phase.

[0011]

In the inverter of the present invention, since the offset voltage is added to the voltage command for each phase when charging the battery, it is possible to take out the controlled DC output for charging the battery at the same time while taking out the AC output.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, the capacitor 7 of the inverter 5 is composed of divided capacitors 7A and 7B, and the neutral point of the generator 4 is connected to the divided point A. 20 is a center tap reactor (tap point is O), and one end is K
Is connected to the U-phase output terminal U of the inverter 5, and the other end L is connected to the V-phase output terminal V of the inverter 5. The positive electrode of the battery 10 is connected to the center tap 21, and the negative electrode is connected to the interconnection point A of the capacitors 7A and 7B via the charging switch 22a and the starter switch 22.
It is connected to the negative electrode N of the inverter DC circuit via b.

Reference numeral 30 is a control circuit for the inverter 5. Three
Reference numeral 1 is a control input (Vsinωt). 32 is a carrier generator for generating a carrier signal, 33 is the control input 3
A converter for converting 1 into a sine wave having a phase difference of 180 ° from the control input 31, 34 and 35 adders, 36 and 37 PWM signal generators (comparators), 38 and 39 sign inverters, 40 and 41 are isolation amplifiers (drivers), the isolation amplifier 40 alternately sends ON / OFF signals to the bases of the transistors T _r1 and T _r3 of the U-phase arm, and the isolation amplifier 41 is the transistor T of the V-phase arm. _An ON / OFF signal is alternately sent to the bases of _r2 and T _r4 as a drive signal.

42 is a charging current command I _B ^* and a current sensor 4
A deviation amplifier that amplifies a deviation from the actual charging current I _B taken out via step 3, and its output voltage (charging voltage command) V _B ^* is added to the U-phase voltage command (to be V _U ^* ). It is added by the device 34. Similarly, the V-phase voltage command (V _V
^* ) Is added by the adder 35. The comparator 36 compares the output of the adder 34 with the carrier signal to perform U-phase PWM.
Output a signal. Similarly, the comparator 37 compares the output of the adder 35 with the carrier signal and outputs the V-phase PWM signal.

In this structure, when the engine 3 is started, the starter time switch 22b is turned on and the charge time switch 22a is turned off. A booster circuit is formed by using one of the transistors, one of the diodes, and the reactor that form the reverse conversion unit 8, boosts the voltage of the battery 10 and performs the reverse conversion operation of the forward conversion unit 6 to drive the generator 4 as a motor. Although driven, the center tap reactor 20 plays the role of this reactor in the present embodiment.

During charging, the charging switch 22a is turned on.
Since the starter switch 22b is turned off, the main circuit has the connection configuration shown in FIG. Since the charging voltage command V _B ^* is added to both the U-phase voltage command V _U ^* and the V-phase voltage command V _V ^* , the U-phase terminal U Voltage (shown in FIG. 5A) appears, and this voltage is applied to the series circuit of the K-O portion of the center tap reactor and the battery 10. Further, the V-phase terminal V is Voltage appears (shown in FIG. 5 (B)), this voltage is added to the series circuit of the O-L portion of the center tap reactor 20 and the battery 10, and V _UV = Vsinωt.・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・
(3) appears (shown in FIG. 5A).

The waveform of the current I _B flowing into the battery 10 at this time is shown in FIG. 5D, and the waveform of the offset voltage V _B is shown in FIG.
Each is shown in (E).

The center tap reactor 20 has a high impedance with respect to the AC component Vsinωt of the above equations, but has a low impedance with respect to the voltage V _B , in which the mutual inductance M is offset as shown in FIG. Since (1 indicates leakage inductance), the circuit of FIG. 1 forms a charging circuit equivalently as shown in FIG. 3 when the battery is charged.

Thus, in this embodiment, the inverter 5
Thus, the controlled charging power can be taken out while taking out the desired AC output.

Although the inverter 5 of the above embodiment is a single-phase inverter, the same effect can be obtained also in the case of a three-phase inverter if the center tap reactor is connected to two phases.

[0022]

As described above, the inverter of the present invention can take out a controlled direct current output for battery charging at the same time as taking out an alternating current output. There is an advantage that it is not necessary to provide a dedicated circuit (battery charger) for charging.

Therefore, when the present invention is applied to the above-mentioned portable engine generator, etc., it is possible to further reduce the size and to reduce the cost because the battery charger is not provided. There is something.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a circuit diagram for explaining the operation of the above embodiment.

FIG. 3 is a diagram showing an equivalent circuit at the time of charging in the above embodiment.

FIG. 4 is a diagram for explaining the operation of the reactor during charging in the above embodiment.

FIG. 5 is a waveform diagram for explaining the operation of the above embodiment.

FIG. 6 is a circuit diagram showing a conventional engine-type power generator.

FIG. 7 is a diagram showing a main circuit of an inverter in the conventional example.

[Explanation of symbols]

 1 Fuel Tank 2 Refueling Device 3 Gas Turbine Engine 5 Power Converter 6 Forward Converter 7 Electrolytic Capacitor 8 Inverse Converter 10 Battery 20 Center Tap Reactor 22a Charging Switch 22b Starter Switch 30 Inverter Control Circuit 31 Control Input 32 Carrier signal generator 34, 35 Adder 36, 37 PWM signal generator (comparator) 40, 41 Driver 42 Deviation amplifier 43 Current sensor

Claims (3)

[Claims] 1. An inverter comprising switching elements bridge-connected, wherein a reactor with a center tap is connected between output terminals, and a battery is charged between the center tap of the reactor with the center tap and an intermediate potential of an inverter DC circuit. An inverter with a battery charging function, wherein a battery is connected via a switch for charging, and when the battery is charged, an offset voltage is added to a voltage command for each phase of the inverter control circuit. 2. A battery is a battery for an engine starter, an inverter is connected to a generator connected to the engine, and a negative electrode of the battery is connected to a negative electrode of an inverter DC circuit via a starter switch. The inverter with a battery charging function according to claim 1, wherein: 3. The inverter is a single-phase inverter,
The control circuit includes a circuit that generates a U-phase voltage command and a V-phase voltage command, a U-phase PWM signal generation circuit that compares the carrier signal with the U-phase voltage command and the V-phase voltage command, and a V-phase PWM signal generation circuit.
The output of the phase PWM signal generation circuit, the output of the U-phase PWM signal generation circuit and the inverted signal of the output to the positive and negative switching elements of the U-phase arm of the inverter, the output of the V-phase PWM signal generation circuit and the inverted signal of the output, respectively. A driver for each positive / negative switching element of the V-phase arm of the inverter, a circuit for calculating a deviation between the battery charging current and the battery charging command value, and outputting a charging voltage command are provided, and the charging voltage command is used as an offset voltage for each phase. The inverter with a battery charging function according to claim 1 or 2, wherein the inverter is added to the voltage command.