JPH0710173B2 - Power supply - Google Patents

Description

TECHNICAL FIELD The present invention relates to a switching type power supply device (AC / DC converter) for producing a stable DC power supply from an AC power supply.

<< Prior Art >> Recently, a power factor correction type AC / DC converter as shown in Fig. 2 has been developed. In FIG. 2, a sine wave AC input is full-wave rectified by a rectifier circuit 10 composed of a diode bridge and input to a booster type chopper circuit 20 described in detail below. The chopper circuit 20 includes a switching element Q1 that is turned on / off by a PWM (pulse width control) circuit 31 at a frequency sufficiently higher than an AC power source, and an inductor L1 that is connected in series between the switching element Q1 and the output of the rectifier circuit 10.
And a diode D1 and a capacitor C1 connected in series at both ends of the switching element Q1 so that a current flows through the inductor L1 when the switching element Q1 is off. The capacitor C1 has a considerably large capacity, and a smoothed and voltage-stabilized DC output (described later) is taken out from both ends thereof. The capacitor C2 is a small-capacity capacitor for absorbing high-frequency ripple, and is not essential to this device.

A signal of the full-wave rectified output voltage V1 of the rectifier circuit 10 is input to a differential amplifier 33 via a VCA (voltage control type variable gain amplifier) 32. The current I1 flowing through L1 flowing through the inductor L1 of the chopper circuit 20 is detected by the current transformer 34, and the low frequency component signal thereof is input to the differential amplifier 33. The PWM circuit 31 operates according to the differential output of the differential amplifier 33, and changes the drive pulse width (ON time) of the switching element Q1 so that the differential output is minimized. In addition, the output voltage V2 of the chopper circuit 20
Error with respect to the reference voltage V _S of is detected by the error amplifier 35,
This output becomes the control voltage of VCA32.

In the above configuration, in the differential amplifier 33, the waveform of the input V1 of the chopper circuit 20 and the waveform of the current I1 flowing through the inductor L1 are compared, and the PWM waveform is changed so that the current waveform changes following the voltage waveform. The circuit 31 changes the on-time of the switching element Q1.

When the switching element Q1 is on, current flows from the rectifier circuit 10 to the inductor L1 through the switching element Q1 and energy is stored in the inductor L1. The current increase value during the ON period is proportional to the input voltage V1 and also to the ON time. When the switching element Q1 is turned off, a current due to the release of energy accumulated in the switching element Q1 is superimposed on the output of the rectifier circuit 10 and is supplied to the capacitor C1 side.

As a result, the pulse width control by comparing the input voltage waveform and the current waveform of the inductor L1 acts to shorten the ON time of the switching element Q1 as the input voltage V1 increases. By this control, the change of the current waveform becomes almost equal to the full-wave rectified waveform of the input voltage. That is, when viewed from the AC input side, the input voltage and the input current have substantially the same waveform and there is no phase difference, and the state is almost the same as when the load is a resistor. The above is the operation of the first control means.

Moreover, the second control means operates as follows. Output voltage
The gain of VCA32 decreases as V2 is higher than the reference voltage V _S , and the gain of VCA32 increases as V2 is lower than V _S. This VCA32 is a circuit through which the waveform signal of the input voltage in the first control means passes, and the gain thereof is a basic parameter of the first control means. That is, if the output voltage V2 is too high, the ON time of the switching element Q1 is shortened,
On the other hand, if it is too low, the on-time is extended to act so that the output voltage V2 approaches the reference voltage V _S.

As described in detail above, in this type of power supply device,
The input current changes almost according to the AC input voltage, and becomes almost sinusoidal with no phase difference, and the relationship between the voltage and current seen from the AC power supply side is almost the same as when a resistor is added (the power factor is improved. Be done). Therefore, unlike the conventional capacitor-input type rectifier circuit, a large pulse current does not flow intensively in a short time, the restrictions on the withstand current characteristics of the circuit elements are relaxed, and various AC power lines are connected. It is possible to reduce noise that has an adverse effect. Further, the output voltage is kept constant even when the AC input voltage fluctuates or the voltage rank is changed by the boosting action of the chopper circuit and the feedback control action of the output voltage by the second control means. You can As a result, it is possible to easily configure a power supply device that does not require switching at all and is suitable for, for example, an AC 100V power supply to an AC 200V power supply.

<< Problems to be Solved by the Invention >> According to the power supply device having the above configuration, it is possible to deal with a wide voltage range of the AC input power supply without adjustment. However, since the chopper circuit 20 is a boost type, when the voltage peak value of the AC power supply becomes equal to or higher than the output voltage V2, the on / off drive of the switching element Q1 stops, the switching element Q1 remains off, and the rectifier circuit 10 causes the inductor L1, diode
A current flows intermittently through the output capacitor C1 through D1. This is the same operation as the conventional capacitor-input type rectifier circuit. Even if the output voltage V2 is almost equal to the target voltage, the power factor improving effect of this device is not achieved and the input current becomes a pulse current synchronized with the AC power supply. . Such a state is not the correct use state of the device.

Another cause of the switching of the switching element Q1 being stopped is a failure of the switching control system such as the PWM circuit 31. When this control system fails, the switching element Q1 stops switching regardless of the voltage of the AC power supply. In this case, the output voltage depends on the voltage of the AC power supply, and in some cases, the output voltage V2 may fall within the target voltage range.

The conventional power supply device does not take the measures against abnormalities as described above, and if the output voltage is within the target range, even if there is an abnormality, you will not notice it and the power factor improvement effect of the original device cannot be achieved. I sometimes kept using it.

The present invention has been made in view of the above problems, and an object thereof is to provide a power supply device capable of analytically detecting an abnormality related to a switching element of a chopper circuit and an output voltage.

<< Means for Solving the Problem >> Therefore, in the present invention, in the power supply device having the above-described configuration, the switching stop detecting means for detecting that the switching element is not driven on / off and the output voltage of the chopper circuit are An output voltage check means for detecting that the voltage has exceeded a set voltage, and a first logic gate for notifying an abnormal input voltage in response to detection signals from both the switching stop detection means and the output voltage check means. And a second logic gate for notifying a switching stop abnormality under normal output in response to the detection signal of the switching stop detection means and the absence of the detection signal of the output voltage check means.

<< Operation >> When the voltage of the AC power supply becomes higher than the output voltage and the switching element is fixed to OFF, a detection signal is generated from the switching stop detection means, and a detection signal is also output from the output voltage check means. Is output. In this state, the output signal of the first logic gate changes in response to the input signal to notify the abnormality of the input voltage.

The voltage of the AC power supply is within the normal range, and if switching stops due to a failure of the switching control system,
The detection signal of the switching stop detecting means is generated, but the detection signal of the output voltage checking means is not generated. In this state, the output signal of the second logic gate changes in response to it, and the switching stop abnormality under normal output is notified.

<< Embodiment >> FIG. 1 shows an embodiment of the present invention, in which a switching stop detection circuit 50 and a comparator 40 as an output voltage checking means are added to the same power supply device as in FIG. . Since the configuration and operation of the power supply device itself have already been described in detail, the configuration and operation newly added will be described below.

Switching stop detection circuit 50 in the embodiment of FIG.
Is an auxiliary secondary winding L2 attached to the inductor L1 in the chopper circuit 20, a filtering circuit 51 for filtering a high-frequency signal induced in the secondary winding L2, and an output level of the filtering circuit 51. And a binarization circuit 52 for generating a notification signal when the threshold value is exceeded. The output side of the binarization circuit 52 is connected to a light emitting diode lamp that lights up in response to the notification signal, a circuit that notifies an abnormality to other external circuits, and the like.

In this configuration, when the switching element Q1 is driven on / off by the PWM circuit 31, a current accompanied by a high frequency component due to switching flows through the inductor L1 and the switching element Q1 and a high frequency signal is induced in the auxiliary secondary winding L2. To be done. This high frequency signal is input to the binarization circuit 52 via the filtering circuit 51. When the switching element Q1 is performing the switching operation, the input of the binarization circuit 52 exceeds the threshold value, and the notification signal is not output. When the switching of the switching element Q1 is stopped and fixed to OFF, the high frequency signal is not induced in the auxiliary secondary winding L2, the input of the binarization circuit 52 falls below the threshold value, and the notification signal is output at this time. .

The comparator 40 compares the output voltage V2 of the chopper circuit 20 with the set voltage (V _S + Δ), and generates a detection signal when the output voltage V2 becomes equal to or higher than the set voltage. When the voltage of the AC power supply exceeds the target value of the output voltage V2, the switching operation of the switching element Q1 stops as described above, and the detection signal is generated from the switching stop detection circuit 50. Output voltage at the same time
V2 exceeds the target value due to the influence of excessive input voltage, and becomes the set voltage (V _S + Δ) of the comparator 40 or more.
A detection signal also occurs from 40. Therefore, as shown in FIG. 3, if the detection circuit of the switching stop detection circuit 50 and the detection signal of the comparator 40 are input to the AND gate G1 (first logic gate), the AND gate is activated when the input voltage is abnormal. A notification signal is output from G1 to notify the abnormality.

Depending on the combination of the target value of the output voltage and the voltage of the AC power supply, the output voltage V2 may fall within the target voltage range even if the PWM circuit 31 or the like fails and the switching element Q1 is fixed off. In this case, no detection signal is generated from the comparator 40, but a detection signal is generated from the switching stop detection circuit 50, which indicates that the switching control system is abnormal. Therefore, as shown in FIG. 3, an AND gate G2 (second logic gate) that receives the output of the switching stop detection circuit 50 and the inverted output of the comparator 40 as an input is provided to detect an abnormality in the switching control system of this type. G2
You can know from the output of.

There are various specific circuit means for detecting the switching stop of the switching element Q1, and the present invention can be implemented by any means.

<< Effects of the Invention >> As described in detail above, according to the present invention, in the power supply device of the power factor correction system, the switching stop of the chopper circuit and the abnormal rise of the output voltage can be detected analytically. , The AC power supply voltage is too high for the target voltage, and the switching control system failure can be detected analytically. Even if the output voltage is within the target range, the original power factor improvement effect can be obtained. Abnormal usage conditions that cannot be played can be detected quickly, and the fail-safety of using this type of device is greatly improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a power supply device according to an embodiment of the present invention, FIG. 2 is a configuration diagram of a conventional power supply device, and FIG. 3 is a block diagram of an abnormality detection signal processing circuit in the embodiment device of the present invention. is there. 10 …… Rectifier circuit 20 …… Chopper circuit 40 …… Comparator (output voltage check means) 50 …… Switching stop detection circuit G1 …… First logic gate G2 …… Second logic gate

Claims (1)

[Claims] 1. A rectifying circuit for full-wave rectifying an AC power source to obtain a pulsating current output, a switching element that is driven on / off at a frequency sufficiently higher than the AC power source, and an output of the rectifying circuit together with this switching element. An inductor connected in series between the switching element and a diode and a capacitor connected in series at both ends of the switching element so that a current flows through the inductor when the switching element is turned off. A first chopper circuit for controlling the drive pulse width of the switching element so that the waveform of the low-frequency component of the current flowing through the inductor or the switching element changes following the waveform of the output voltage of the rectifier circuit. Control means and to reduce the error between the output voltage of the chopper circuit and the reference voltage. Second control means for controlling the drive pulse width of the switching element, switching stop detection means for detecting that the switching element is no longer ON / OFF driven, and the output voltage of the chopper circuit is equal to or higher than a set voltage. Output voltage check means for detecting that the input voltage abnormality is detected in response to the detection signals from both the switching stop detection means and the output voltage check means, and the switching stop A power supply device comprising: a second logic gate for notifying a switching stop abnormality under normal output in response to the detection signal of the detection means and the absence of the detection signal of the output voltage check means. .