JPH0785656B2 - Voltage control device for constant voltage constant frequency inverter - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a voltage control device for a constant voltage constant frequency inverter device.

[Technical background of the invention] The input voltage of an inverter device used as an auxiliary power source of an electric vehicle is supplied from an overhead wire via a current collector.

However, the capacity of substations for electric railways is small for economic reasons, considering the number of electric cars in the same substation, the time lag that consumes a large amount of starting current, and the overhead line. Since the power itself is also supplied over a very long distance, the voltage of the overhead wire often changes drastically when the electric car is started. Further, since the electric car itself travels at a high speed, there are many opportunities to instantaneously disconnect from the overhead wire of the current collector.

In this way, the input voltage of the inverter device used in the electric car is extremely unstable and its fluctuation range is large,
The inverter device is required to maintain a quick response and a stable constant output voltage in response to a sudden change in the input voltage and a large voltage change.

For this reason, conventionally, a constant voltage constant frequency inverter device (hereinafter referred to as an inverter) has been used as an inverter device for an electric vehicle, which will be described below with reference to the block diagram of FIG. In FIG. 1, reference numeral 1 is a reference voltage generator, and a reference voltage Ex serving as a reference value of the output voltage of the inverter device is applied to one input terminal of the adder 7. The output voltage −Eo of the inverter is added to the other input terminal of the adder 7, and the deviation value ΔE is obtained in the adder 7. This deviation value ΔE is input to the flow phase (flow angle) generating section 2 to obtain the flow phase α ₁ . Here, the conduction phase generator 2 is, for example, a delay compensator for stabilizing the output voltage of the inverter device, a ramp function generator that outputs a repetitive waveform signal at a cycle synchronized with the output frequency of the inverter device, and this ramp. A comparator that compares the output of the function generator with the output of the delay compensator and outputs a conduction phase α, and a conversion element such as a thyristor for each phase of the inverter according to the time width of the conduction phase α of the comparator. It is composed of a phase pulse distributor that outputs a set conduction phase α ₁ that gives ON and OFF pulses to.

Damping control unit 3 for preventing the oscillation of the output voltage of the inverter when the input voltage of the inverter changes and the load changes.
To the inverter, the input voltage Ei and the output current Io of the inverter are input, and the damping term α ₂ determined by this is output to the adder 8. The set conduction phase α ₁ is also output to the adder 8 and is passed through in the adder. The flow phase (flow angle) α is output,
As a result, the output voltage of the inverter is controlled.

[Problems of the Background Art] In such a configuration, in order to keep the output voltage constant regardless of the input voltage of the inverter and the state of the load, the first
As shown in the figure, the voltage deviation ΔE between the reference voltage Ex and the output voltage Eo
To control the flow phase of the conversion element. However, in the conduction phase control of the conversion element, the range of possible values is limited in order to protect the conversion element itself and keep the output frequency constant. This will be described with reference to FIG. 2 as an example. In the input voltage range N lower than the value of the input voltage at which the output voltage can be kept constant by the maximum possible conduction phase αmax, the conduction phase of the conversion element is always fixed to the maximum conduction phase αmax. Here, when the input voltage is lowered and the conduction phase is fixed to the maximum conduction phase αmax as described above, the damping control unit 3 changes the conduction phase of the dynamic range M required for preventing the output voltage oscillation. The maximum flow phase αmax cannot be increased in the increasing direction, and it is inevitable that the effect for preventing the oscillation of the output voltage is reduced. Further, when the load is inductive such as a cooler, it is difficult to suppress the oscillation of the output voltage due to the change of the load. This is because the inrush current at the start of the inductive load is large, and the current of the inductive load lags behind the voltage phase as compared with the resistive load.

[Object of the Invention] The present invention has been made in view of the above circumstances, and is caused by fluctuations of an inductive load such as a cooler even in an input voltage range in which the conduction phase of the conversion element of the inverter is fixed to the maximum phase. An object of the present invention is to provide a voltage control device for a constant voltage constant frequency inverter device that does not cause output voltage oscillation.

[Summary of the Invention] In order to achieve the above-mentioned object, the present invention relates to the first aspect of the invention, in which the maximum phase of the current flowing through the conversion element of the inverter is determined so as to protect the conversion element itself and keep the output frequency constant. The setting maximum conduction phase is obtained by subtracting the dynamic range of damping control required to prevent oscillation of the output voltage from the current phase, and the conduction phase of the conversion element is set as the maximum conduction phase when the input voltage drops. Below an equal input voltage,
By fixing the current-flowing phase of the conversion element to the set maximum current-flowing phase, the dynamic range of damping control is secured even in the range where the input voltage drops, so that the fluctuation of the output voltage due to the change of inductive load such as cooler is prevented. To prevent.

In order to achieve the above object, the present invention provides a second invention,
The dynamic range of the damping control necessary to prevent the oscillation of the output voltage was added to the conduction phase of the conversion element of the inverter from the maximum conduction phase determined to protect the conversion element itself and keep the output frequency constant. If the input voltage is lower than the set minimum current flow phase and the input voltage drops and the current flow phase of the conversion element becomes equal to the set minimum current flow phase, fix the current flow phase of the conversion element to the set minimum current flow phase. Thus, the dynamic range of the damping control is secured even in the range where the input voltage is reduced to prevent the output voltage from vibrating due to the change of the inductive load such as the cooler.

[Embodiment of the Invention] The method of the present invention will be described below. First, an embodiment of the device of the present invention will be described with reference to FIG. FIG. 3 shows a control block added to the apparatus of FIG. 1 for fixing the conduction phase of the conversion element of the inverter to the set maximum conduction phase when the input voltage of the inverter is less than the set maximum conduction phase input voltage. It was done. That is, the set maximum conduction phase input voltage Eith output from the set maximum conduction phase input voltage generator 5 is input to the adder 9. The input voltage Ei of the inverter is input to the adder 9, and the value obtained by subtracting the input voltage Ei from the set maximum conduction phase input voltage Eith is output to the minimum value 0 limiter 4. The minimum value 0 limiter 4 passes the value input from the adder 9 when the value is greater than 0, or 0 when a value less than 0 is input through the coefficient unit 6 and the adder 7
Output to. In addition to the input from the coefficient unit 6, the output voltage Eo of the inverter and the reference voltage Ex output from the reference voltage generator 1 are input to the adder 7. The voltage deviation ΔE output from the adder 7 is input to the current-flowing phase generating section 2 and the set current-flowing phase α ₁ is output from the current-flowing phase generating section 2. The input voltage is applied to this to prevent the output voltage. The output voltage is controlled by the conduction phase α obtained by adding the damping term (damping conduction phase) α ₂ determined by Ei and the output current Io.

The operation of the device having the control block for fixing the conduction phase of the conversion element to the set maximum conduction phase when the input voltage configured as shown in FIG. 3 is equal to or less than the set maximum conduction phase input voltage will be described below. To do. In FIG. 3, the input voltage Ei
And set maximum current phase input voltage Eith, and input voltage
When Ei is higher, the value obtained by subtracting the input voltage Ei from the set maximum distribution phase input voltage Eith output from the adder 9 is 0.
Since it becomes smaller, 0 is output from the minimum value 0 limiter 4. Therefore, 0 is output from the coefficient unit 6 to the adder 7.

That is, when the input voltage Ei is higher than the set maximum distribution phase input voltage Eith, the distribution phase α is controlled so as to output a constant voltage determined by the reference voltage Ex.

FIGS. 4 (a) and 4 (b) are for explaining the above. When the input voltage Ei is higher than the set maximum conduction phase input voltage Eith, the output voltage Eo ₂ should be kept constant. The value of the conduction phase α is controlled according to the value of the input voltage Ei. Also,
In this range, the dynamic range M of the phase required for performing damping control is secured. If the input voltage Ei is less than the set maximum conduction phase input voltage Eith, the third
In the figure, the value obtained by subtracting the input voltage Ei from the set maximum conduction phase input voltage Eith output from the adder 9 is 0 or more, so the minimum value 0 limiter 4 outputs this value to the coefficient unit 6.

The coefficient unit 6 fixes the conduction phase α to the value obtained by subtracting the input voltage Ei from the set maximum conduction phase input voltage Eith within the range of the set maximum conduction phase input voltage or less to the set maximum conduction phase α _0. The value multiplied by a constant K that can be determined is input to the adder 7. With this input, the adder 7 has the same effect as lowering the reference voltage Ex as shown in the set maximum flowing phase range A in FIG. 4, and this effect makes the flowing phase α the set maximum flowing phase α ₀ . The voltage deviation ΔE becomes
Entered in. The voltage deviation ΔE obtained in this way
As a result, the flow phase α ₁ generated by the flow phase generator 2 has a value fixed to the set maximum flow phase α ₀ , and the dynamic range required for damping control is secured between the flow phase α ₁ and the maximum flow phase α max. Will be things.

The maximum conduction phase input voltage Set by the action shown in Fig. 4
With the following input voltage Ei, as shown in FIG. 5, a variable range of the commutation phase α remains between the maximum commutation phase α max and the set maximum commutation phase α _0. Since the dynamic range M of damping control necessary for preventing voltage oscillation is secured, it is possible to perform voltage control while preventing output voltage oscillation even when an inductive load such as a cooler changes.

Next, another embodiment of the present invention will be described with reference to FIG. 6, in which the horizontal axis Ei is the input voltage of the inverter and the vertical axis Eo.
Indicates the output voltage of the inverter. C is a stable output voltage control range, D is a stable output voltage control range when the method of the present invention is not used, F is a set maximum conduction phase range, G is a set minimum conduction phase range, H is an output voltage fluctuation range, and Ei. ₁ is the minimum input voltage, Eith is the set maximum conduction phase input voltage, Either 'is the set minimum conduction phase input voltage, Ei ₃ is the maximum input voltage, Eo ₁ is the minimum output voltage, Eo ₂ is the normal output voltage, Eo ₃ Is the maximum output voltage. Fig. 6 shows that when the input voltage drops below the maximum input voltage Ei ₃ and the current phase of the conversion element of the inverter becomes equal to the set minimum conduction phase (Fig. 4G), the set minimum conduction phase becomes It is a fixed voltage control device.

Even in this voltage control device, the output voltage does not oscillate due to the inductive load variation even in the range of the input voltage in which the conduction phase of the conversion element of the inverter is fixed to the maximum phase.

Further, if the voltage control device (method of fixing to the set minimum conduction phase) and the voltage control device (method of fixing to the set maximum conduction phase) described above are combined, a stable output voltage with respect to fluctuation of inductive load can be obtained. It is possible to expand the range of the input voltage that can obtain the stable output voltage control range D in the case of not using the device of the present invention to the stable output voltage control range C of the device of the present invention.

[Effects of the Invention] As described above, according to the present invention, the output voltage oscillates due to the inductive load variation such as the cooler even in the input voltage range in which the conduction phase of the conversion element is fixed at the maximum phase. It is possible to provide a voltage control device for a constant-voltage constant-frequency inverter device that does not have a problem.

[Brief description of drawings]

FIG. 1 is a block diagram of a device for carrying out a method for controlling a flow phase of a conventional constant voltage constant frequency inverter device, and FIG.
The figure shows the relationship between the input voltage Ei and the conduction phase α controlled by the block diagram of FIG. 1, and FIG. 3 shows the setting of the conduction phase of the constant voltage constant frequency inverter device according to the present invention. FIG. 4 is a block diagram showing an example of an apparatus for fixing the set maximum conduction phase within an input voltage range below an input voltage, and FIG. 4 is a constant voltage constant frequency inverter apparatus for explaining the operation of the apparatus of FIG. FIG. 5 is a diagram showing the relationship between the input voltage, the output voltage, and the conduction phase, and FIG. 5 is a diagram showing the relationship between the damping controllable dynamic range and the set maximum conduction phase and the maximum conduction phase of the device of FIG. FIG. 6 shows a constant voltage constant frequency inverter device, and a control method by the device of FIG.
It is the figure which showed that the range of the input voltage which can control the output voltage stably when performing the control method applied to the minimum conduction phase similarly to the control of the figure can be expanded. 1 ... reference voltage generator, 2 ... current phase generator, 3 ...
Damping control unit, 4 ... Minimum value 0 limiter, 5 ... Set maximum current phase input voltage generator, 6 ... Coefficient unit, 7 ...
Adder, 8 ... Adder, 9 ... Adder, Ex ... Reference voltage, Ei ... Input voltage, Eo ... Output voltage.

Claims (2)

[Claims] 1. A constant voltage constant frequency inverter device in which electric power is supplied to an inductive load by the output of a constant voltage constant frequency inverter composed of a conversion element, and the conversion element is controlled by a conduction phase. First calculation means for obtaining the set conduction phase of the conversion element according to the deviation between the voltage and the reference voltage, and the input voltage and the output current of the inverter prevent the oscillation of the output voltage due to the input voltage fluctuation and the load fluctuation. The second calculating means for obtaining the damping flow phase of the conversion element is compared with the input voltage of the inverter and the set value, and when the input voltage becomes equal to or less than the set value, the first calculating means is obtained. Control means for adding a predetermined value to the deviation and outputting the set maximum flow phase from the first calculating means; and a set flow level obtained by the first and second calculating means. A voltage control device for a constant voltage constant frequency inverter device, comprising: an output unit that outputs a conduction phase obtained by adding a phase and a damping conduction phase to the conversion element. 2. A constant-voltage constant-frequency inverter device for supplying electric power to an inductive load by the output of a constant-voltage constant-frequency inverter composed of a conversion element and controlling the conversion element according to the conduction phase, wherein the output of the inverter First calculation means for obtaining the set conduction phase of the conversion element according to the deviation between the voltage and the reference voltage, and the input voltage and the output current of the inverter prevent the oscillation of the output voltage due to the input voltage fluctuation and the load fluctuation. The second computing means for obtaining the damping flow phase of the conversion element is compared with the input voltage of the inverter and the set value, and when the input voltage exceeds the set value, it is obtained by the first computing means. Control means for subtracting a predetermined value from the deviation to output the set minimum flow phase from the first calculating means, and set flow position obtained by the first and second calculating means A voltage control device for a constant voltage constant frequency inverter device, comprising: an output unit that outputs a conduction phase obtained by adding a phase and a damping conduction phase to the conversion element.