JP4669502B2 - Abnormality detection method for resonant switching power supply and resonant switching power supply - Google Patents

Description

  The present invention relates to an abnormality detection method for a resonant switching power supply apparatus and a resonant switching power supply apparatus in which one or a plurality of switching elements that switch an output from a DC power supply are switched so that a resonant circuit resonates and supplies the power. It is about.

For example, as shown in FIG. 1, the resonance type switching power supply device has an output from a DC power source such as a secondary battery B, and a switching circuit Q 1, Q 2 includes a resonance circuit 4 including a primary winding L 1 of a transformer T. It switches so that it may resonate and it is comprised so that a power supply may be supplied from the secondary side of the transformer T.
A switching power supply device normally performs a switching operation close to a square wave for both a current waveform and a voltage waveform. In a resonant switching power supply device, either or both of a current waveform and a voltage waveform are fully or partially resonant in a resonance circuit. Thus, a sinusoidal switching operation is performed. As a result, the switching loss that occurs when the voltage and current during switching are simultaneously turned on can be reduced, the rate of current change per unit time can be reduced, and the amount of noise generated can be reduced.

Patent Document 1 includes two switching elements connected in series, detects a voltage across one switching element (a source voltage of the other switching element), and turns on the other switching element based on the detection signal. Thus, a resonance type switching power supply device that prevents both switching elements from being turned on simultaneously is disclosed.
Patent Document 2 discloses a deterioration diagnosis device that detects the deterioration of a DC power supply device by wavelet transforming the waveform of the output voltage of the DC power supply device and comparing the representative value of the wavelet transformed waveform with a reference value. Yes.
JP 2007-006614 A Japanese Patent Laying-Open No. 2005-287108

In a resonant switching power supply device, a shunt resistor using a plurality of resistors or a shunt resistor is conventionally used to detect an abnormal increase (loss of resonance) of load current and switching current. There is a problem that occurs.
The present invention has been made in view of the above-described circumstances. In the first and third inventions, an abnormal increase (resonance deviation) in load current and switching current can be detected without using a resistor. An object of the present invention is to provide a method for detecting an abnormality in a resonant switching power supply device.
It is an object of the second, fourth, and fifth inventions to provide a resonance type switching power supply device that can detect an abnormal increase (loss of resonance) of load current and switching current without using a resistor.

  According to a first aspect of the present invention, there is provided an abnormality detection method for a resonance type switching power supply apparatus comprising one or more switching elements for switching an output from a DC power supply and a resonance circuit, wherein the switching element causes the resonance circuit to resonate. In the abnormality detection method of the resonance type switching power supply apparatus that supplies power by switching to the voltage, the voltage values at both ends of the switching element are detected, the detected voltage values are sampled in time series, and the sampled data is wavelet The maximum value and the predetermined value obtained by the conversion and wavelet transform are compared, and an abnormal increase in the current flowing through the switching element is predicted based on the comparison result.

  A resonant switching power supply device according to a second aspect of the present invention comprises one or more switching elements that switch an output from a DC power supply and a resonance circuit, and the switching element is switched so that the resonance circuit resonates. In the resonant switching power supply device configured to supply power, means for detecting a voltage value across the switching element, means for sampling a plurality of voltage values detected by the means in time series, and Means for wavelet transforming a plurality of sampled data; means for comparing a maximum value and a predetermined value as a result of the wavelet transform by the means; and an abnormal increase in the current flowing through the switching element based on the comparison result of the means. And prediction means for predicting.

  In the resonant switching power supply device abnormality detection method according to the first invention and the resonant switching power supply device according to the second invention, one or a plurality of switching elements resonate the output from the DC power supply and the resonant circuit resonates. Switch to supply power. The voltage values at both ends of the switching element are detected, and a plurality of detected voltage values are sampled in time series. Wavelet transform is performed on a plurality of sampled data, and a maximum value and a predetermined value as a result of the wavelet transform are compared. Based on the comparison result, an abnormal increase in the current flowing through the switching element is predicted.

  According to a third aspect of the present invention, there is provided an abnormality detection method for a resonance type switching power supply apparatus comprising a transformer, one or more switching elements for switching an output from a DC power supply, and a resonance circuit, the switching element being the resonance circuit. In the abnormality detection method of the resonance type switching power supply device that switches so as to resonate and supplies power from the secondary side of the transformer, the voltage value at both ends of the switching element is detected, and the detected voltage value is time-series A plurality of samples, wavelet transform of the sampled data, compare the maximum value of the wavelet transform result and a predetermined value, and predict an abnormal increase in the current flowing through the switching element based on the comparison result And

  A resonance-type switching power supply device according to a fourth aspect of the present invention includes a transformer, one or more switching elements that switch output from a DC power supply, and a resonance circuit. The switching element resonates with the resonance circuit. In the resonant switching power supply device configured to supply power from the secondary side of the transformer, means for detecting a voltage value across the switching element, and a voltage value detected by the means Means for time-sequential sampling, means for wavelet transforming the data sampled by the means, means for comparing the maximum value and the predetermined value obtained by the wavelet transform, and the comparison result of the means And a predicting means for predicting an abnormal increase in the current flowing through the switching element.

  In the resonance type switching power supply apparatus according to the third aspect of the invention and the resonance type switching power supply apparatus according to the fourth aspect of the invention, the resonance circuit resonates the output from the DC power supply with one or a plurality of switching elements. Switch to supply power from the secondary side of the transformer. The voltage values at both ends of the switching element are detected, and a plurality of detected voltage values are sampled in time series. Wavelet transform is performed on a plurality of sampled data, and a maximum value and a predetermined value as a result of the wavelet transform are compared. Based on the comparison result, an abnormal increase in the current flowing through the switching element is predicted.

  According to a fifth aspect of the present invention, the predicting means is configured to predict an abnormal increase in the current flowing through the switching element when the comparison result is greater than a predetermined value. It is characterized by being.

  In this resonant switching power supply device, when the comparison result shows that the maximum value of the wavelet transform result is larger than a predetermined value, the predicting means predicts an abnormal increase in the current flowing through the switching element.

  According to the abnormality detection method of the resonant switching power supply device according to the first and third aspects of the invention, it is possible to detect an abnormal increase (loss of resonance) of the load current and the switching current without using a resistor, and to reduce the loss due to the resistor Can be reduced.

  According to the resonance type switching power supply device according to the second, fourth, and fifth inventions, it is possible to detect an abnormal increase (resonance loss) of the load current and the switching current without using a resistor, and to reduce the loss due to the resistor. be able to.

Hereinafter, the present invention will be described with reference to the drawings illustrating embodiments thereof.
FIG. 1 is a block diagram showing the main configuration of an embodiment of a resonant switching power supply apparatus abnormality detection method and a resonant switching power supply apparatus according to the present invention.
In this resonant switching power supply device, two N-channel FETs Q1 and Q2 are connected in series to a battery B which is a DC power supply, the drain of the FET Q1 is connected to the anode of the battery B, and the source of the FET Q2 is connected to the cathode of the battery B. Each is connected.

A voltage resonance capacitor Crv and a series resonance circuit including a primary winding L1 of the transformer T and a current resonance capacitor Cri are connected in parallel to the FET Q2 to form a resonance circuit 4. The winding start end of the primary winding L1 is connected to the drain of the FET Q2.
The gates of the N-channel FETs Q1 and Q2 are respectively connected to a PWM (Pulse Width Modulation) control unit 1 and are turned on / off alternately by the PWM control unit 1. The PWM control unit 1 is constituted by a microcomputer, and detects and samples the voltage value at the connection node between the source of the FET Q1 and the drain of the FET Q2 by the voltage detection means (means for detecting the voltage value at both ends) 2.

The secondary windings L2 and L3 connected in series of the transformer T are aligned with the winding direction of the primary winding L1, the winding start end of the secondary winding L2 is the anode of the diode D1, and the secondary winding L3 The winding end is connected to the anode of the diode D2, and the cathodes of the diodes D1 and D2 are connected to the anode terminal of the electrolytic capacitor C. The cathode terminal of the electrolytic capacitor C is connected to the connection node of the secondary windings L2 and L3.
A resistance RL of a load device is connected in parallel to the electrolytic capacitor C which is a smoothing capacitor.

The operation of the resonant switching power supply device having such a configuration will be described below.
The PWM control unit 1 alternately turns on / off the gates of the FETs Q1 and Q2 at the resonance frequencies of the current resonance circuits L1 and Cri and the voltage resonance circuits L1 and Crv.
When the FET Q1 is on and the FET Q2 is off, a current flows through the primary winding L1, the current resonance capacitor Cri is charged, and an electromotive force is induced on the secondary side of the transformer T. At that time, a voltage corresponding to the output voltage of the battery B and the winding ratio of the primary winding L1 and the secondary winding L3 is induced to the secondary side of the transformer T.

Next, when the FET Q1 is off and the FET Q2 is on, the electric charge charged in the current resonance capacitor Cri is discharged through the primary winding L1, and a current flows in a direction opposite to that at the time of charging. An electromotive force is induced on the secondary side. At that time, a voltage corresponding to the voltage across the current resonance capacitor Cri and the turn ratio of the primary winding L1 and the secondary winding L2 is induced on the secondary side of the transformer T.
The amount of power induced on the secondary side of the transformer T is set and controlled by changing the ON period of the FET Q1, that is, the charging period of the current resonance capacitor Cri and changing the voltage across the current resonance capacitor Cri. .

Immediately after the FET Q1 is turned off, an exciting current due to the exciting inductance of the primary winding L1 flows through a body diode (not shown) of the FET Q2, and during this time, the FET Q2 is turned on. As a result, the FET Q2 performs zero voltage / zero current switching, and the switching loss becomes extremely small.
When the FET Q2 is turned off, the discharge from the current resonance capacitor Cri is almost completed, the flowing current is small, and the voltage resonance capacitor Crv is in a voltage quasi-resonance state, so that the switching loss is extremely small. .

Immediately after the FET Q2 is turned off, the circulating current flows through a body diode (not shown) of the FET Q1, and during this time, the FET Q1 is turned on. As a result, the FET Q1 performs zero voltage / zero current switching, and the switching loss becomes extremely small.
When the FET Q1 is turned off, the charging of the current resonance capacitor Cri is almost completed, the flowing current is small, and the voltage resonance capacitor Crv is in a voltage quasi-resonance state, so that the switching loss is extremely small. .
As described above, the switching loss of the FETs Q1 and Q2 is extremely small.

The abnormality detection operation of the resonant switching power supply device according to the present invention will be described below with reference to the flowchart of FIG.
The PWM control unit 1 sets the parameter K to 0 (S3) after a predetermined time has elapsed after the load device having the resistance RL is activated (S1). Next, it is determined whether or not the load device is operated (S5). If not, the voltage value at the connection node of the FETs Q1 and Q2 detected by the voltage detection means 2 is sampled (S7).

Next, after adding 1 to the parameter K (S9), the PWM control unit 1 determines whether the parameter K is equal to or greater than N (N is a natural number), which is the number of data necessary for the wavelet transform operation. If the parameter K is greater than or equal to N (S11), the parameter K is set to N (S13).
If the load device is operated (S5), the PWM controller 1 deletes the data sampled so far (S23), sets the parameter K to 0 (S3), and resamples.
If the parameter K is not N or more (S11), the PWM controller 1 determines whether or not the load device is being operated (S5).

After the parameter K is set to N (S13), the PWM control unit 1 performs wavelet transform calculation using the N data sampled in a time series most recently (S15), and the peak value of the calculation result is It is determined whether it is larger than a reference value (predetermined value) (S17).
If the peak value is larger than the reference value (S17), the PWM control unit 1 predicts an abnormal increase in the amount of current flowing through the primary winding L1 of the transformer T (S19), and prevents the abnormal increase in the current amount. Next, each of the gates of the FETs Q1 and Q2 is PWM-controlled (S21). Next, it is determined whether or not the load device is operated (S5).
If the peak value is not larger than the reference value (S17), the PWM controller 1 determines whether or not the load device is being operated (S5).

  The wavelet transform is one of known methods used for frequency analysis, like the Fourier transform. In the Fourier transform, the waveform is expressed by enlarging and adding the sine wave and cosine wave, while in the wavelet transform, the waveform is expressed by enlarging, reducing, translating, and adding the small wave (wavelet). To do. In the Fourier transform, only the frequency component is localized, so time series information is lost. In the wavelet transform, both the time component and the frequency component are localized, and a small wave (basis function; Since the width of the Mexican hat function, the French hat function, etc.) changes, the frequency resolution is good.

  With computers, it is difficult to handle continuous quantities, and if a signal is forcibly applied to a continuous wavelet transform formula, a considerable amount of information is lost and inverse transform cannot be performed, so discrete wavelet transform that considers inverse transform is performed. Is called. The discrete wavelet transform is also referred to as multi-resolution analysis because it repeatedly performs a process of decomposing the original signal into a high-frequency component and a low-frequency component and further decomposing the decomposed high-frequency component into a high-frequency component and a low-frequency component.

  For example, in a resonant switching power supply device with a rated value of 2.6 A as shown in FIG. 1, the peak value of the value obtained by wavelet transforming the load current and the primary voltage value of the transformer has the relationship shown in FIG. This shows that there is a significant relationship between the two. FIG. 3 shows that when a load current exceeding the rated value 2.6 A flows, the switching frequency is changed and resonance is lost.

  Further, in the resonance type switching power supply device (here, the rated value is not 2.6A) as shown in FIG. 1, the load is changed rapidly as shown in FIG. 4 (a). When the voltage is increased from 3.0 A to 7.5 A, the source voltage value of the FET Q1 detected by the voltage detection means 2 before and after that changes as shown in FIG. In that case, the source current value of the FET Q1 changes as shown in FIG. 4B, and the value obtained by wavelet transforming the source voltage value of the FET Q1 changes as shown in FIG.

4 (a), 4 (b) and FIG. 5, when the load fluctuates suddenly, the value obtained by wavelet transforming the source voltage value of the FET Q1 before the resonance shift occurs and the source current value of the FET Q1 increases. It can be seen that increases. Therefore, resonance deviation can be predicted in advance by comparing the value obtained by wavelet transform of the primary voltage value of the transformer with a reference value determined in advance by actual measurement or calculation.
In the above-described embodiment, the insulating resonance switching power supply device has been described. However, the same can be applied to a resonance switching power supply device such as a non-insulating chopper method.

It is a block diagram which shows the principal part structure of embodiment of the abnormality detection method of the resonance type switching power supply device which concerns on this invention, and a resonance type switching power supply device. It is a flowchart which shows the abnormality detection operation | movement of the resonance type switching power supply device which concerns on this invention. It is a characteristic figure which shows the example of a relationship between the load current and the peak value of the value which carried out wavelet transform of the primary side voltage value of the transformer of a resonance type switching power supply device. It is explanatory drawing for demonstrating the abnormality detection method of the resonance type switching power supply device which concerns on this invention. It is explanatory drawing for demonstrating the abnormality detection method of the resonance type switching power supply device which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 PWM control part 2 Voltage detection means (means to detect voltage value between both ends)
4 Resonant circuit B Battery C Electrolytic capacitor Cri Current resonant capacitor Crv Voltage resonant capacitor D1, D2 Diode L1 Primary winding L2, L3 Secondary winding RL Resistance of load device T Transformer Q1, Q2 FET

Claims (5)

An abnormality of a resonant switching power supply device that includes one or a plurality of switching elements that switch an output from a DC power source and a resonance circuit, and the switching element switches so that the resonance circuit resonates and supplies power. In the detection method,
Detecting the voltage value at both ends of the switching element, sampling a plurality of detected voltage values in time series, wavelet transforming a plurality of sampled data, comparing a maximum value and a predetermined value as a result of wavelet transform, and comparing results An abnormality detection method for a resonant switching power supply device, wherein an abnormal increase in current flowing through the switching element is predicted based on the above. A resonance circuit comprising one or more switching elements for switching output from a DC power source and a resonance circuit, wherein the switching element is configured to switch the resonance circuit to resonate and supply power. Type switching power supply
Means for detecting a voltage value across the switching element, means for sampling a plurality of voltage values detected by the means in time series, means for wavelet transforming the data sampled by the means, and means for wavelet transform A resonance type switching power supply comprising: means for comparing the maximum value and the predetermined value of the result obtained; and prediction means for predicting an abnormal increase in the current flowing through the switching element based on the comparison result of the means. A transformer, one or more switching elements for switching an output from a DC power source, and a resonance circuit, wherein the switching element is switched so that the resonance circuit resonates, and the secondary side of the transformer In the abnormality detection method of the resonance type switching power supply that supplies power from
Detecting the voltage value at both ends of the switching element, sampling a plurality of detected voltage values in time series, wavelet transforming a plurality of sampled data, comparing a maximum value and a predetermined value as a result of wavelet transform, and comparing results An abnormality detection method for a resonant switching power supply device, wherein an abnormal increase in current flowing through the switching element is predicted based on the above. A transformer, one or more switching elements for switching an output from a DC power source, and a resonance circuit, wherein the switching element is switched so that the resonance circuit resonates, and the secondary side of the transformer In the resonant switching power supply configured to supply power from
Means for detecting a voltage value across the switching element, means for sampling a plurality of voltage values detected by the means in time series, means for wavelet transforming the data sampled by the means, and means for wavelet transform A resonance type switching power supply comprising: means for comparing the maximum value and the predetermined value of the result obtained; and prediction means for predicting an abnormal increase in the current flowing through the switching element based on the comparison result of the means.   5. The resonant switching power supply according to claim 2, wherein the predicting unit is configured to predict an abnormal increase in a current flowing through the switching element when the comparison result indicates that the maximum value is larger than a predetermined value. apparatus.

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