JP2003235267A - Rectifier - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rectifier having highly stabilized output voltage control characteristics, which can suppress fluctuation of a capacitor voltage without causing an increase in power loss, enlargement of a device in size and an increase in the number of components. <P>SOLUTION: In the rectifier 1, an AC voltage is inputted into a rectification circuit 2 having a switching element 3 from an AC power source to obtain a DC voltage Vrec as an output, the voltage Vrec is smoothed by a reactor 4 and a capacitor 5, and the voltage is supplied to a load 6. In this rectifier, a differential value Vd of a capacitor voltage obtained by detecting a vibration current flowing to the reactor 4 by a current detector 12 is added to an error signal Ve created by a voltage controller 9 from a capacitor voltage Vc and a capacitor voltage command signal Vc*, thereby creating an ignition phase command signal Vref for determining a controlled firing angle of the element 3. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention converts an input AC voltage into a DC voltage, which is mounted on a vehicle auxiliary power supply device mounted on an electric vehicle running on an AC overhead line section, for example.
The present invention relates to a forward conversion device that supplies DC power to the next-stage inverter device and the like.

[0002]

2. Description of the Related Art FIG. It is a block diagram which shows the forward conversion apparatus in the conventional auxiliary power supply device for AC overhead line trains shown in FIG. In the figure, 1 is an AC power supply, 2 is a rectifier circuit, 3 is a switching element that constitutes a rectifier circuit, 4 is a smoothing reactor, 5 is a smoothing capacitor, 6 is a load connected to the smoothing capacitor, and 7 is a capacitor 5. Voltage detector, 8
Is a capacitor voltage command value Vc * generator, 9 is a voltage detection value Vc between the terminals of the capacitor 5 and a capacitor voltage command value Vc
A voltage controller that outputs a difference signal (error signal) Ve of *, 1
Reference numeral 0 is an input voltage detector that detects the power supply voltage, and 11 is a firing circuit that determines the firing control angle of the switching element 3.

As a main circuit operation, a rectifier circuit composed of a switching element 3 whose ignition phase is controlled by a control unit composed of a voltage controller 9 and an ignition circuit 11 for an AC voltage input from an AC power supply 1. Converted to DC voltage at 2. However, the DC voltage Vrec appearing at the output of the rectifier circuit 2 is
The voltage includes a pulsating component of the input AC voltage, and in order to smooth this pulsating component, the reactor 4 and the capacitor 5
Is used to smooth the capacitor voltage and supply it to the load 6.

The operation of the control unit for constant voltage control of the voltage across the terminals of the capacitor 5 is the voltage controller 9 and the voltage detector 7
A voltage error Ve is generated by amplifying the difference (error) between the inter-terminal voltage Vc of the capacitor 5 and the capacitor voltage command value Vc * detected by. Here, the voltage error Ve is the voltage controller 9
When the gain of K1 is K1, the following formula is obtained. Ve = K1 (Vc * -Vc) (1) From the above formula, when there is a difference between the capacitor voltage Vc and the capacitor voltage command value Vc *, the product of this difference and the gain K1 is the voltage. The voltage error Ve is output from the controller 9, which becomes the ignition phase command signal Vref and is input to the next ignition circuit 11.

In the ignition circuit 11, as shown in FIG. 2, the S1 element of the switching element 3 has a negative power supply synchronization signal Vsync detected by the input voltage detector 10 and has a phase from the power supply synchronization signal Vsync. The carrier wave Vcos shifted by 90 degrees and the signal -Vref obtained by inverting the firing phase command signal Vref are compared, and the firing signal is generated at the phase B where -Vref <Vcos.

The S2 element of the switching element 3 is
Power supply synchronization signal Vsync detected by input voltage detector 10
Is positive, and the carrier phase Vcos, which is 90 degrees out of phase with the power supply synchronization signal Vsync, is compared with the firing phase command signal Vref,
The ignition signal is generated at the phase A where Vref> Vcos.

With this configuration, when the capacitor voltage Vc becomes smaller than the capacitor voltage command value Vc *, the voltage error Ve and the ignition phase command signal Vref are positively large, and -Vref is negatively large. , Firing phase command signal Vre
Phases A and B where f, −Vref and carrier Vcos intersect advance,
The ignition control angle θ of the switching element 3 becomes small. As a result, the output voltage average value Vrec of the rectifier circuit 2 increases.

On the contrary, when the capacitor voltage Vc becomes larger than the capacitor voltage command value Vc *, the voltage error Ve and the ignition phase command signal Vref become large negatively, and -Vref becomes positively large, and the ignition phase command signal Vref becomes large. , -Vref and carrier wave Vcos intersect, the phases A and B are delayed, and the ignition control angle θ of the switching element 3 becomes large. As a result, the output voltage average value Vrec of the rectifier circuit 2 decreases. With the above control operation, the voltage across the terminals of the capacitor 5 is controlled to be constant, and a constant DC voltage is supplied to the load 6.

[0009]

In the conventional forward converter as shown in FIG. 8, the output side of the rectifier circuit 2 is composed of the reactor 4 and the capacitor 5, but the voltage across the terminals of the capacitor 5 is When the capacitor voltage Vc is fed back as described above for constant control, the voltage across the terminals of the capacitor 5 is determined by the inductance value L (H) of the reactor 4 and the capacity C (F) of the capacitor 5. There has been a problem that vibration is likely to occur at a frequency f (Hz) = 1 / 2π√LC.

The mechanism of this vibration generation is based on the rectification circuit 2
Since the output side of is composed of the reactor 4 and the capacitor 5, the system is a secondary oscillating system, and feedback control is performed by the voltage controller 9 in order to constantly control the terminal voltage Vc of the capacitor 5 of this system. This is because it is difficult to secure the phase margin of the control system and the control system becomes oscillating. A control system block diagram in this case is shown in FIG. Where K1 is the voltage controller gain, Krec is the rectifier gain, and L is the reactor inductance.
(H) and C are capacitor capacitances (F), and KS1 is voltage detector gain. FIG. 10 shows the frequency characteristics of the gain-phase open loop transfer function of the control system of this block diagram. However, the circuit constants are K1 = 10, Krec = 1, KS1 = 1, L = 0.0
28H, C = 0.014F. From the gain characteristics in FIG. 10, there is a resonance point near 10 Hz and the phase changes abruptly with a delay of 180 degrees, which shows that this control system is oscillatory and has poor stability.

The above vibration generating mechanism will be described from the viewpoint of the operating state with reference to the circuit diagram of FIG. Assuming that the load 6 suddenly increases, the output of the rectifier circuit 2 has the reactor 4, so that the increased energy required by the load cannot be instantaneously supplied from the AC power supply 1, so that the increased energy is supplied from the capacitor 5 to the load. As a result, the voltage across the terminals of the capacitor 5 drops.

Next, since the voltage across the terminals of the capacitor 5 decreases, the capacitor voltage Vc detected by the voltage detector 7 also decreases, and the error signal Ve, which is the output of the voltage controller 9,
The firing phase command signal Vref increases positively, the phases A and B at which the firing phase command signal Vref and the carrier wave Vcos shown in FIG. 2 intersect advance, and the firing control angle θ of the switching element 3 decreases. Thereby, the output voltage average value Vre of the rectifier circuit 2
c increases. As a result, a current due to an error between the output voltage average value Vrec and the voltage of the capacitor 5 flows into the reactor 4, charges the capacitor 5, and recovers the capacitor voltage that has dropped due to a sudden increase in load.

Next, when the voltage of the capacitor 5 is restored and the detected capacitor voltage value Vc becomes equal to the capacitor voltage command value Vc *, the voltage controller 9 sets the difference signal Ve to zero, so that the ignition circuit 11 switches the switching element. Ignition control angle of 3
The output voltage Vrec of the rectifier circuit 2 is narrowed by increasing the phase delay of, but the current flowing in the reactor 4 at this time has a peak value because the phase is advanced by 90 degrees from the capacitor voltage. Since the energy stored in 4 further flows into the capacitor 5, the terminal voltage of the capacitor 5 overshoots the set value. As a result, the voltage error Ve increases negatively, and thus the control operation is performed so as to suppress the voltage increase of the capacitor 5. By repeating this, the capacitor voltage gradually converges to the set value.

As described above, in the conventional configuration, the control operation is performed so as to correct the magnitude of the voltage of the capacitor 5 and then, the overshoot from the set value of the voltage of the capacitor 5 occurs. Inevitably, the voltage of the capacitor 5 oscillates and converges to the set value. Further, when the control gain K1 of the voltage controller 9 is increased, the control operation becomes excessive, and the phenomenon that the capacitor voltage oscillation does not converge occurs, so that it is difficult to increase the control response.

Thus, in the conventional configuration, the capacitor 5
Since the voltage of V is oscillating, the voltage over the set value is applied to the load due to the overshoot of the capacitor voltage, the stable operation of the load is disturbed by the voltage vibration, and the oscillating power flows to the AC power supply 1 side. Therefore, there is a problem that the device connected to the AC power supply side system is affected or an inductive failure occurs in a nearby device.

In order to avoid this problem, conventionally, the gain K1 of the voltage controller 9 of the control unit is reduced to loosen the constant voltage control, or a resistor is inserted between the reactor 4 and the capacitor 5 to generate the vibration power. Is consumed by the resistor to reduce the vibration, or a resonance filter is installed in parallel with the reactor 4 or the capacitor 5 to install the reactor 4 and the capacitor 5.
The means for suppressing the vibration is adopted by absorbing the vibration power generated between the two. However, if the gain K1 of the voltage controller 9 is reduced, the constant voltage control performance of the inter-terminal voltage of the capacitor 5 is degraded, and the method of inserting the resistor is generated by the resistor in a device that handles large power. Loss increases, which leads to an increase in size of the device and unnecessary power consumption.
Further, in the method of installing the resonance filter, it is necessary to install a large resonance filter that can withstand a high voltage, which causes a problem of increasing the size of the device and increasing the number of parts.

The present invention has been made in order to solve the problems of the conventional device as described above, and by adding a control circuit to the conventional configuration, wasteful power loss and resistance increase in size of the device are achieved. An object of the present invention is to obtain a forward conversion device that suppresses the vibration of the reactor 4 and the capacitor 5 and obtains a stable constant voltage between the terminals of the capacitor 5 without using a container or a resonance filter.

[0018]

A forward converter according to the present invention comprises a rectifier circuit having a controllable switching element in a main circuit, a smoothing reactor and a smoothing capacitor provided on the output side of the rectifier circuit. In order to control the terminal voltage of this capacitor to a set constant DC voltage, the switching of the rectifier circuit is performed by using the voltage error signal obtained from the difference between the terminal voltage of the capacitor and the capacitor reference voltage. In the forward conversion device that controls the firing phase of the element and controls the voltage between the terminals of the capacitor to be constant, the signal obtained from the current detector that detects the AC component of the output current of the rectifier circuit is the voltage error signal. In addition to the signal obtained,
By firing the switching element, the inter-terminal voltage of the capacitor is controlled to a stable DC voltage.

Further, the signal obtained from the current detector for detecting the input current of the rectifier circuit is added to the voltage error signal to control the switching element by the signal obtained, whereby the terminal of the capacitor is controlled. The inter-voltage is controlled to a stable DC voltage.

The signal obtained from a current detector for detecting a current flowing through the capacitor on the output side of the rectifier circuit is added to the voltage error signal to control the switching element by firing. As a result, the voltage across the terminals of the capacitor is controlled to a stable DC voltage.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1. 1 is a block diagram showing a forward conversion device according to a first embodiment of the present invention. In FIG. 1, 1 is an AC power supply, 2 is a rectifier circuit, 3 is a controllable switching element that constitutes a rectifier circuit, 4 is a smoothing reactor, 5 is a smoothing capacitor, 6 is a load connected to the capacitor 5, and 7 is Voltage detector between the terminals of the capacitor 5,
8 is a capacitor voltage command generator, 9 is a voltage controller that outputs a difference signal (error signal) Ve between the voltage detection value Vc between the terminals of the capacitor 5 and the capacitor voltage command value Vc *, and 10 is a power supply voltage. An input voltage detector, 11 is a firing circuit that determines the firing control angle of the switching element 3, 12 is a current detector that detects an alternating current component flowing in the reactor 4,
13 is an operational amplifier that multiplies the output of the current detector 12 by a gain K2, and 14 is an adder that adds the output of the operational amplifier 13 to the difference signal Ve. The feature of the first embodiment is that a circuit including 12 to 14 is added.

As the main circuit operation, the AC voltage input from the AC power supply 1 is turned on by the control unit having a function of controlling the terminal voltage of the capacitor 5 composed of the voltage controller 9 and the ignition circuit 11 to be constant. It is converted into a DC voltage by the rectifier circuit 2 composed of the switching element 3 whose arc control angle θ is controlled. The DC voltage Vrec that appears at the output of this rectifier circuit 2 is
The voltage includes a pulsating component of the input AC voltage, and in order to smooth this pulsating component, the reactor 4 and the capacitor 5
Is used to smooth the output voltage and supply it to the load 6 as a constant voltage.

The operation of the control unit for constant voltage control of the voltage across the terminals of the capacitor 5 is the error between the voltage Vc across the terminals of the capacitor 5 detected by the voltage detector 7 by the voltage controller 9 and the capacitor voltage command value Vc *. To generate a voltage error signal Ve. Here, the voltage error signal Ve is given by the following equation when the gain of the voltage controller 9 is K1. Ve = K1 (Vc * -Vc) (1) From the above equation, the voltage error signal Ve is obtained from the voltage controller 9 by multiplying the difference between the capacitor voltage Vc and the capacitor voltage command value Vc * by the gain K1. And is input to the adder 14. The adder 14 adds the capacitor voltage oscillation component differential value signal Vd (differential value Vd of the voltage between the terminals of the capacitor), which is the feature of the first embodiment, to the voltage error signal Ve to create the firing phase command signal Vref. .

A method of creating the capacitor voltage oscillation component differential value signal Vd will be described below. An oscillating current component of the reactor 4 is detected by the current detector 12. Since this oscillating current component is an oscillating current flowing between the capacitor 5 and the reactor 4, if this is ILac, ILac can be expressed by the following equation. ILac = C × dVc / dt (2) From the above equation, ILac is the time differential value of the capacitor voltage multiplied by the capacitor electrostatic capacity C, and the 90 ° phase from the vibration component of the capacitor voltage. Is an advanced value. The gain of the operational amplifier 13 is set to K2, and the gain is inverted to obtain the capacitor voltage oscillation component differential value signal Vd. Therefore Vd
Can be expressed as Vd = -K2 × C × dVc / dt (3)

Therefore, the ignition phase command signal Vref is expressed by the following equation. Vref = Ve + Vd = K1 × (Vc * −Vc) + (− K2 × C × dVc / dt) (4) Compared with the conventional device (1), the voltage error Ve of the capacitor 5 The feature is that the differential value Vd of the voltage oscillation component is added. This firing phase command signal Vr
Input ef to the ignition circuit 11.

In the firing circuit 11, as shown in FIG. 2, the S1 element of the switching element 3 has a negative power supply synchronization signal Vsync detected by the input voltage detector 10 and a phase of 90 degrees from the power supply synchronization signal Vsync. The shifted carrier wave Vcos is compared with the signal −Vref obtained by inverting the firing phase command signal Vref, and −
The firing signal is generated at the phase B where Vref <Vcos.

The S2 element of the switching element 3 is
Power supply synchronization signal Vsync detected by input voltage detector 10
Is positive and the carrier phase Vcos, which is 90 degrees out of phase with the power supply synchronization signal Vsync, is compared with the firing phase command signal Vref, and Vr
The ignition signal is generated at the phase A where ef> Vcos.

With this configuration, when the capacitor voltage Vc becomes smaller than the capacitor voltage command value Vc *, the voltage error Ve becomes positively large. Further, when the capacitor voltage change rate becomes negative, the capacitor voltage oscillation component differential value signal Vd becomes positively large, these are reflected in the ignition phase command signal Vref, and the ignition phase command signal Vref and the carrier wave Vcos intersect. Phase shifts, switching element 3
The ignition control angle θ becomes smaller. As a result, the output voltage average value Vrec of the rectifier circuit 2 increases.

On the contrary, when the inter-terminal voltage Vc of the capacitor 5 becomes larger than the capacitor voltage command value Vc *, the voltage error Ve becomes negatively large. Further, when the capacitor voltage change rate becomes positive, the capacitor voltage oscillation component differential value signal Vd becomes negatively large, which is reflected in the ignition phase command signal Vref, and the ignition phase command signal Vref and the carrier wave Vcos intersect. The phase is delayed, and the firing control angle θ of the switching element 3 becomes large. Thus, the output voltage average value V of the rectifier circuit 2
rec is reduced. By the above control operation, the voltage across the terminals of the capacitor 5 is controlled to be constant, and a constant DC voltage can be supplied to the load 6.

A block diagram of the control system in the configuration of FIG. 1 is shown in FIG. Here, K1 is a voltage controller gain, Krec is a rectifier gain, L is a reactor inductance (H), C is a capacitor capacity (F), KS1 is a voltage detector gain, KS2 is a current detector gain, and K2 is a calculation. It is the amplifier gain. FIG. 4 shows the frequency characteristics of the gain / phase open-loop transfer function of the control system in this block diagram. However, the circuit constant is K1
= 10, Krec = 1, KS1 = 1, L = 0.028H, C =
0.014F, KS2 = 1, K2 = 1. From the gain characteristic of FIG. 4, the resonance point existing in the vicinity of 10 Hz in FIG. 10 of the conventional method is eliminated, and the phase slowly delays as the frequency increases and the phase margin also increases. , It turns out that this control system is not oscillatory. That is, it can be seen that the stability of the control system can be improved.

The above vibration generating mechanism will be described from the viewpoint of the operating state with reference to the circuit diagram of FIG. Assuming that the load 6 suddenly increases, since the reactor 4 is present at the output part of the rectifier circuit 2, the increased energy cannot be instantaneously supplied from the AC power source 1 to the load 6, so that the increased energy is increased from the capacitor 5 to the load 6. Will supply the capacitor 5
The inter-terminal voltage Vc of the capacitor starts to decrease, and the voltage change rate of the capacitor 5 has a negative maximum value. A schematic diagram of this state is shown in FIG.

The fact that the rate of change of the inter-terminal voltage Vc of the capacitor 5 has a negative maximum value means that the second item of the equation (4) of the ignition phase command signal Vref is -K2 × C × dVc / dt (= Vd )
Takes a positive maximum value, and therefore the capacitor voltage oscillation component differential value signal Vd takes a positive maximum value. By adding this to the voltage error Ve, the magnitude of the firing phase command signal Vref is positively set to -Vref before the voltage of the capacitor 5 decreases and the voltage error Ve increases as shown in FIG. The magnitude can be increased negatively. This is the feature of the first embodiment.

By this operation, the phase angles A and B at which the firing phase command signal Vref and the carrier wave Vcos shown in FIG. 2 intersect can be advanced earlier than the conventional method, and the switching element 3
The ignition control angle θ becomes smaller. As a result, the average value Vrec of the output voltage of the rectifier circuit 2 increases before the voltage of the capacitor 5 greatly decreases. As a result, a current due to the output voltage average value Vrec and the voltage error of the capacitor 5 flows in the reactor 4, charges the capacitor 5, and operates to recover the voltage before the voltage of the capacitor 5 greatly decreases due to a sudden increase in load.

Next, when the change rate of the voltage Vc between the terminals of the capacitor 5 becomes positive and starts to increase, the capacitor voltage oscillation component differential value signal Vd takes a negative value. Therefore, the detected voltage Vc between the capacitor terminals is the capacitor voltage command value Vc *
Before being equal to, the magnitude of the firing phase command signal Vref is negatively increased and the magnitude of -Vref is positively increased, and the phase angles A and B at which the firing phase command signal Vref and the carrier wave Vcos intersect are delayed. By increasing the firing control angle θ of the switching element 3, it is possible to obtain an operation of reducing the output voltage Vrec of the rectifier circuit 2 and braking so that the capacitor voltage does not overshoot the set value. This is the feature of the first embodiment, and by this operation, the overshoot from the set value of the terminal voltage of the capacitor 5 can be significantly reduced as compared with the conventional device as compared with the conventional device. That is, highly stable capacitor voltage control can be realized.

As described above, in the conventional configuration of FIG. 8, control is performed so as to correct the magnitude of the voltage of the capacitor 5 after the magnitude of the voltage of the capacitor 5 has changed, so that the capacitor voltage exceeds the set value when the load changes. Shooting is unavoidable, and the capacitor voltage oscillates to a set value while oscillating and is unstable, whereas in the device of the first embodiment, in addition to the magnitude of the voltage of the capacitor 5, the voltage change rate (= capacitor voltage oscillation Since the magnitude of the component differential value signal Vd) is taken into consideration, control can be performed to suppress the capacitor voltage before it changes. Therefore, the characteristic feature is that the capacitor voltage overshoot at the time of load change can be effectively suppressed, and highly stable capacitor voltage control characteristics can be obtained.

Due to the above effects, the voltage of the capacitor 5 can be controlled stably, so that a voltage higher than a set value is applied to the load, stable operation of the load is hindered, and oscillating power flows to the AC power source 1 side. As a result, it is possible to suppress the influence on the device connected to the power system side and the occurrence of inductive failure.

Further, the gain of the voltage controller of the control unit, which has been conventionally used, is reduced to loosen the constant voltage control, or a resistor is inserted in the vibration path of the reactor and the capacitor, and the vibration power is consumed by the resistor. In order to suppress the vibration or to suppress the vibration by installing the resonance filter in parallel with the reactor or the capacitor to absorb the vibration power of the reactor and the capacitor, the gain K of the voltage controller 9 is increased.
In the means for dropping 1, the constant voltage control performance of the voltage across the terminals of the capacitor 5 is lowered, and in the means for inserting the resistor, the loss generated in the resistor is large in the device handling a large electric power, and In the means for installing a resonance filter, a large resonance filter that withstands a high voltage must be installed, which leads to an increase in the size of the device and an increase in the number of parts. Although there is a problem, according to the device of the first embodiment, the current detector 12, the operational amplifier 13, and the adder 14 are only added without wasteful power loss and size increase of the device. Can be composed of inexpensive electronic parts, and the installation space for the parts is very small. Therefore, the conventional problems can be solved.

Although the first embodiment has been described with respect to the forward conversion device having a single-phase alternating current as an input, it can be applied to a forward conversion device having a multi-phase alternating current as an input. Although the rectifier circuit section has a mixed bridge configuration, it may have a full bridge configuration. Further, the first embodiment is characterized in that the switching element is ignited by the signal obtained by adding the signal obtained from the (differential oscillation component) differential value of the voltage across the capacitor to the voltage error signal. The configuration of the ignition circuit 11 and the type of the switching element 3 are not limited to the means shown in FIG. 1 and can be widely applied. Although the current detector 12 is described by using the AC CT, it goes without saying that the DC CT and the high pass filter can be used in combination.

Embodiment 2. FIG. 6 is a configuration diagram showing a forward conversion device according to the second embodiment of the present invention. In FIG. 6, a high-pass filter (HPF) 15 and an absolute value circuit 16 are added, and the position of the current detector 12 is set on the input side of the rectifier circuit 2. Is the same as the configuration.

In FIG. 6, since the rectifier circuit 2 has no energy storage element, the instantaneous power is the same on the input side and the output side of the rectifier circuit 2. Therefore, even in the configuration of FIG. 6, the absolute value circuit 16 takes the absolute value of the input current of the rectifier circuit 2 and inputs the absolute value to the HPF 15 to thereby obtain the first embodiment.
As in the above configuration, the capacitor voltage oscillation component differential value signal V
d can be obtained, and the same control performance as that of the first embodiment can be obtained. In the configuration of FIG. 6, if there is an existing input current detector, it can also be used, and there is an advantage that the number of current detectors need not be increased. Further, as the current detector 12, both an AC CT and a DC CT can be used.

Embodiment 3. FIG. 7 is a configuration diagram showing a forward conversion device according to Embodiment 3 of the present invention. In FIG. 7, the configuration is the same as that of the first embodiment except that 12 current detectors are installed at positions where the current of the capacitor 5 is detected.

In the configuration of FIG. 7, if there is an existing current detector for protecting the capacitor 5 or the like, it can be used also as this, and there is an advantage that the number of current detectors need not be increased. Further, since the current flowing through the capacitor 5 is AC, the current detector 12 can be used for both AC CT and DC CT.

[0043]

As described above, according to the forward converter of the present invention, a rectifier circuit having a controllable switching element in the main circuit, and a smoothing reactor and a smoothing reactor provided on the output side of the rectifier circuit. For controlling the terminal voltage of the capacitor to a set constant DC voltage, using the voltage error signal obtained from the difference between the terminal voltage of the capacitor and the capacitor reference voltage, the rectification In the forward conversion device that controls the ignition phase of the switching element of the circuit and controls the voltage between the terminals of the capacitor to be constant, the signal obtained from the current detector that detects the AC component of the output current of the rectifier circuit is It is possible to control the voltage between the terminals of the capacitor to a stable DC voltage by controlling the ignition of the switching element with the signal obtained in addition to the voltage error signal. Therefore, the vibration of the smoothing reactor and the smoothing capacitor can be suppressed and a stable constant voltage can be obtained between the terminals of the capacitor, without using a resistor or a resonance filter that would cause unnecessary power loss and increase the size of the device. You can

Further, the signal obtained from the current detector for detecting the input current of the rectifying circuit is added to the voltage error signal to control the switching element by the signal obtained, whereby the terminal of the capacitor is controlled. Since it becomes possible to control the DC voltage to a stable DC voltage, the same effects as above can be obtained, and if there is an existing input current detector, this can also be used, and the number of current detectors can be increased. There is an advantage that can be eliminated.

The signal obtained from the current detector for detecting the current flowing through the capacitor on the output side of the rectifier circuit is added to the voltage error signal to control the ignition of the switching element. As a result, it becomes possible to control the voltage across the terminals of the capacitor to a stable DC voltage, so that it is possible to obtain the same effect as described above, and if there is an existing current detector, this can also be used.
There is an advantage that the number of current detectors need not be increased.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a forward conversion device according to a first embodiment of the present invention.

2 is an operation explanatory view of a switching element firing circuit of the apparatus of FIG. 1. FIG.

FIG. 3 is a block diagram of a control system of the apparatus shown in FIG.

4 is a gain / phase frequency characteristic diagram of a control system of the apparatus of FIG.

5 is an explanatory diagram of an ignition phase command signal of the apparatus of FIG. 1 and a conventional apparatus.

FIG. 6 is a configuration diagram showing a forward conversion device according to a second embodiment of the present invention.

FIG. 7 is a configuration diagram showing a forward conversion device according to a third embodiment of the present invention.

FIG. 8 is a configuration diagram showing a conventional forward conversion device.

FIG. 9 is a block diagram of a control system of a conventional forward conversion device.

FIG. 10 is a gain / phase frequency characteristic diagram of a control system in a conventional forward conversion device.

[Explanation of symbols]

1 AC power supply 2 Rectifier circuit 3 Switching element 4 Smoothing reactor 5 Smoothing capacitor 6 Load 7 Voltage detector 8 Capacitor voltage command generator 9 Voltage controller 10 Input voltage detector 11 Ignition circuit 12 Current detector 13 Gain 14 Addition 15 High-pass filter (HPF) 16 Absolute value circuit.

Claims (3)

[Claims] 1. A main circuit includes a rectifying circuit having a controllable switching element, a smoothing reactor and a smoothing capacitor provided on the output side of the rectifying circuit, and a terminal voltage of the capacitor is set. In order to control to a constant DC voltage, by using the voltage error signal obtained from the difference between the voltage between the terminals of the capacitor and the capacitor reference voltage, the ignition phase of the switching element of the rectifier circuit is controlled, and the terminal of the capacitor is controlled. In the forward conversion device that controls the inter-voltage to be constant, the signal obtained from the current detector that detects the AC component of the output current of the rectifier circuit is a signal obtained by adding the voltage error signal to the switching element. A forward conversion device characterized in that the voltage across the terminals of the capacitor is controlled to a stable DC voltage by performing arc control. 2. The main circuit includes a rectifying circuit having a controllable switching element, a smoothing reactor and a smoothing capacitor provided on the output side of the rectifying circuit, and a terminal voltage of the capacitor is set. In order to control to a constant DC voltage, by using the voltage error signal obtained from the difference between the voltage between the terminals of the capacitor and the capacitor reference voltage, the ignition phase of the switching element of the rectifier circuit is controlled, and the terminal of the capacitor is controlled. In the forward conversion device for controlling the inter-voltage to be constant, the signal obtained from the current detector for detecting the input current of the rectifier circuit is added to the voltage error signal to control the ignition of the switching element. Thus, the forward conversion device is characterized in that the terminal voltage of the capacitor is controlled to a stable DC voltage. 3. The main circuit includes a rectifying circuit having a controllable switching element, a smoothing reactor and a smoothing capacitor provided on the output side of the rectifying circuit, and a voltage between terminals of the capacitor is set. In order to control to a constant DC voltage, by using the voltage error signal obtained from the difference between the voltage between the terminals of the capacitor and the capacitor reference voltage, the ignition phase of the switching element of the rectifier circuit is controlled, and the terminal of the capacitor is controlled. In the forward conversion device that controls the inter-voltage to be constant, the signal obtained from the current detector that detects the current flowing in the capacitor on the output side of the rectifier circuit is the signal obtained by adding the voltage error signal to A forward conversion device characterized in that the voltage across the terminals of the capacitor is controlled to a stable DC voltage by controlling the ignition of the switching element.