JP7650219B2 - DC/DC converter and power supply device - Google Patents

Description

The present invention relates to a DC/DC converter and a power supply device equipped with the DC/DC converter.

In recent years, rapid chargers for electric vehicles are becoming increasingly large, from 100 kW to 200 kW, as the battery capacity of electric vehicles increases. This has made it increasingly important to make the power supply devices used in rapid chargers smaller, more efficient, and less expensive.

The power supply device of a quick charger has a power supply unit consisting of an AC/DC converter and a DC/DC converter. Conventionally, voltage-current type DC/DC converters have been used as DC/DC converters, but in recent years, in light of the above-mentioned background, current-resonant type DC/DC converters such as LLC type and CLLC type, which allow for compact size, high efficiency and low cost, have been used. Current-resonant type DC/DC converters require control by changing the drive frequency over a wide range depending on the input voltage, output voltage and output current.

The CHAdeMO standard, which is the standard for charging electric vehicles, specifies that the ripple noise of a quick charger should be, for example, less than 1.5 App at 10 Hz or less, and less than 3 App at 5 Hz or less. In the case of a current-resonant DC/DC converter, the ripple noise contained in the input voltage (input voltage ripple) propagates from the primary switching circuit via a high-frequency isolation transformer to the secondary rectifier circuit, and is output as ripple noise contained in the output current (output current ripple). As ripple noise has a negative effect on the battery of an electric vehicle, a filter circuit is generally provided between the DC/DC converter and the preceding AC/DC converter to reduce the ripple noise.

In order to reduce the size and cost of a filter circuit, it is necessary to increase the cutoff frequency of the filter circuit. However, if the cutoff frequency of the filter circuit is increased, the low-frequency components of the ripple noise will flow out of the filter circuit. For example, if the AC power supply connected to the input side of the AC/DC converter is a three-phase AC power supply, the harmonic current (AC ripple) of 300 Hz or 360 Hz, which is the sixth harmonic of the AC current input from the AC power supply, will flow out of the filter circuit.

On the other hand, lowering the cutoff frequency of the filter circuit can reduce the low-frequency components of the ripple noise, but it also leads to larger choke coils and larger electrolytic capacitors. As a result, the filter circuit and the power supply device become larger and more expensive.

Non-Patent Document 1 describes a method for suppressing ripples in a high-frequency switching rectifier using a feedforward circuit. The high-frequency switching rectifier includes a full-wave rectifier section and a DC/DC converter section, and the DC/DC converter section includes a filter circuit and a DC/DC converter.

If the cutoff frequency of the filter circuit is lowered (low-frequency design) to reduce the sixth harmonic noise of 300 Hz or 360 Hz input from the three-phase AC power supply, the weight and volume of the filter circuit will account for 10% or more of the entire high-frequency switching rectifier. In this regard, the high-frequency switching rectifier of Non-Patent Document 1 can obtain an input/output ripple ratio equal to or greater than that of a low-frequency design by adding a feedforward circuit, even if the cutoff frequency of the filter circuit is increased.

However, the ripple suppression method described in Non-Patent Document 1 depends on the circuit type specific to the DC/DC converter described in Non-Patent Document 1, and cannot be applied to DC/DC converters with different circuit types. Therefore, the ripple suppression method described in Non-Patent Document 1 cannot be applied to current resonant DC/DC converters.

Patent Document 1 describes a method for changing at least one of the switching period and the dead time of the switching elements in the primary circuit in a DC/DC converter equipped with an LLC series resonant circuit. This method makes it possible to reduce ripple noise in the output current output from the secondary circuit.

However, in a current resonant DC/DC converter, the switching period of the switching element is the main control element that controls the output, and the dead time of the switching element is an element that affects the resonance conditions. Therefore, changing at least one of the switching period and the dead time to reduce ripple noise may have a negative effect on the output control and the resonance conditions.

Patent Document 2 describes a method for performing feedforward control according to the amplitude of the pulsation of the output voltage in addition to feedback control in a lighting device that converts AC power supplied from an AC power source into DC current and outputs it to a light source. This method makes it possible to reduce ripple noise at twice the frequency of the AC power source.

However, the method described in Patent Document 2 cannot achieve the above-mentioned effect if the rate of change in output current relative to input voltage change is not constant. In the case of a current-resonant DC/DC converter, the input voltage ripple varies depending on the output current value of the preceding AC/DC converter. Therefore, if the method described in Patent Document 2 is applied to a current-resonant DC/DC converter, there is a possibility that the output current ripple will increase.

Patent No. 6132887 JP 2020-173913 A

Tadakazu Aoki and 1 other person, "A method for suppressing output voltage ripple of a high-frequency switching rectifier using a feedforward circuit," [online], 1989, IEEJ Transactions on Electrical Engineering, Vol. 109, No. 1, [searched on September 3, 2021], Internet <URL: https://www.jstage.jst.go.jp/article/ieejias1987/109/1/109_1_10/_pdf/-char/ja>

The present invention has been made in consideration of the above circumstances, and its objective is to provide a DC/DC converter and a power supply device that can reduce output ripple without increasing the size and cost of the filter circuit.

In order to solve the above problems, a DC/DC converter according to the present invention comprises:
a primary side switching circuit including a switching element that switches an input voltage;
An isolation transformer,
a secondary side rectifier circuit connected to the primary side switching circuit via the isolation transformer;
A control unit that controls at least the switching element;
A DC/DC converter comprising:
The control unit is
a first control unit that generates a first control command value for bringing an output from the secondary side rectifier circuit closer to a predetermined target value;
a gain generating unit that extracts an output ripple included in an output from the secondary side rectifier circuit and generates a gain for making the output ripple equal to or smaller than a predetermined value;
a second control unit that extracts an input voltage ripple included in the input voltage input to the primary side switching circuit, and generates a second control command value based on the input voltage ripple and the gain;
and a third control unit that controls the switching element based on the first control command value and the second control command value.

With this configuration, a second control command value is generated based on the gain for reducing the output ripple (e.g., output current ripple or output voltage ripple) to a predetermined value or less and the input voltage ripple extracted from the input voltage, and the switching element is controlled based on the first control command value and the second control command value for bringing the output from the secondary rectifier circuit closer to a predetermined target value, so that the output ripple can be reduced accurately.

In addition, with this configuration, low-frequency ripple noise can be reduced even if the cutoff frequency of the filter circuit provided in the front stage of the DC/DC converter is increased, making it possible to reduce the size, cost, and weight of the filter circuit.

In the DC/DC converter,
the first control unit generates the first control command value so as to bring at least one of an output current and an output voltage output from the secondary side rectifier circuit closer to the predetermined target value;
The gain generation unit can be configured to extract an output current ripple contained in the output current output from the secondary side rectifier circuit as an output from the secondary side rectifier circuit, and to generate a gain for reducing the output current ripple to a predetermined value or less.

In the DC/DC converter,
The first control unit is
an output current detection unit that detects a current value of the output current;
A first calculation unit that calculates a difference between the current value and the target value;
A first PI control unit that generates the first control command value by a PI calculation based on the difference.

In the DC/DC converter,
The gain generating unit is
a current ripple extraction unit that extracts the output current ripple;
a rectification unit that rectifies the output current ripple;
a second calculation unit that calculates a difference between the output current ripple rectified by the rectification unit and the predetermined value;
A second PI control unit that generates the gain by a PI calculation based on the difference.

In the DC/DC converter,
The second control unit is
an input voltage ripple extraction unit that extracts the input voltage ripple;
A multiplier that multiplies the input voltage ripple and the gain to generate the second control command value.

In the DC/DC converter,
the gain generation unit generates N gains corresponding to the output ripples of N frequencies (N is an integer equal to or greater than 2);
the second control unit generates the N second control command values based on the input voltage ripples of the N frequencies and the N gains;
The third control unit can be configured to control the switching elements based on the first control command value and the N second control command values.

In order to solve the above problems, a power supply device according to the present invention comprises:
An AC/DC converter;
A filter circuit provided on a DC end side of the AC/DC converter;
and any one of the DC/DC converters connected to the AC/DC converter via the filter circuit.

The present invention provides a DC/DC converter and a power supply device that can reduce output ripple without increasing the size and cost of the filter circuit.

1 is an example of a block diagram of a power supply device according to a first embodiment; 1 is an example of a block diagram of a DC/DC converter according to a first embodiment; 1A and 1B are examples of waveform diagrams showing the relationship between input voltage ripple and output current ripple, in which (A) is a waveform diagram of a conventional DC/DC converter, and (B) is a waveform diagram of the DC/DC converter according to the first embodiment. FIG. 11 is an example of a block diagram of a power supply device according to a second embodiment. FIG. 11 is an example of a block diagram of a DC/DC converter according to a second embodiment.

Below, we will explain an embodiment of a DC/DC converter and a power supply device according to the present invention with reference to the attached drawings.

[First embodiment]
FIG. 1 shows an example of a block diagram of a power supply device 1A according to a first embodiment of the present invention, and FIG. 2 shows an example of a block diagram of a DC/DC converter 2A according to the first embodiment of the present invention.

As shown in FIG. 1, the power supply device 1A includes an AC/DC converter 3, a filter circuit 4, and a DC/DC converter 2A. The power supply device 1A generates a desired DC current based on AC power supplied from an AC power source 5 (e.g., a commercial power source with a three-phase AC output), and supplies the DC current to a battery 6 (e.g., a lithium-ion battery of an electric vehicle).

The AC/DC converter 3 is composed of a power conversion unit that performs AC/DC conversion operations and is composed of multiple switching elements (for example, six switching elements that make up three arms in the case of a three-phase AC power supply), and a control unit that controls the power conversion unit. The AC/DC converter 3 converts AC power input from the AC power supply 5 into DC power through AC/DC conversion operations, and outputs it to the DC/DC converter 2A via the filter circuit 4.

The filter circuit 4 is an LC filter circuit composed of a choke coil and an electrolytic capacitor. The cutoff frequency of the filter circuit 4 is set relatively high so as to block ripple noise caused by switching of the AC/DC converter 3, and is configured to pass low-frequency ripple noise (e.g., ripple noise of 300 Hz or 360 Hz). Note that at least a part or all of the filter circuit 4 may be included in the AC/DC converter 3, or may be included in the DC/DC converter 2A.

The DC/DC converter 2A generates a desired DC current (charging current) based on the DC input voltage input from the AC/DC converter 3, and supplies the DC current to the battery 6. The DC/DC converter 2A has terminals T1 to T4, with terminals T1 and T2 connected to the AC/DC converter 3 via the filter circuit 4, and terminals T3 and T4 connected to the battery 6.

The ripple noise input to the DC/DC converter 2A typically includes switching noise and switching ripple that occurs in synchronization with the switching frequency of the switching elements of the AC/DC converter 3, and AC ripple that occurs in synchronization with the frequency of the AC power source 5 (50 Hz or 60 Hz).

Since the switching frequency is on the order of several tens of kHz to 100 kHz, the switching noise and switching ripple can be largely cut by the filter circuit 4, which has a relatively high cutoff frequency. The AC ripple is, for example, a harmonic six times the frequency of the AC power supply 5 (50 Hz or 60 Hz), and has a low frequency of 300 Hz or 360 Hz. For this reason, the AC ripple passes through the filter circuit 4.

When ripple noise (input voltage ripple) of the input voltage input to the DC/DC converter 2A is superimposed as ripple noise (output current ripple) on the output current output from the DC/DC converter 2A, the output current ripple will adversely affect the battery 6. Therefore, in the DC/DC converter 2A according to this embodiment, a current gain (corresponding to the "gain" of the present invention) is generated to reduce the output current ripple to a predetermined value or less, and the output current ripple is reduced by using the current gain to feedforward control the input voltage ripple.

As shown in FIG. 2, the DC/DC converter 2A according to this embodiment is composed of a power conversion unit 10 and a control unit 20A.

The power conversion unit 10 includes a primary side switching circuit 11, an LC resonant circuit 12, an isolation transformer 13, and a secondary side rectifier circuit 14. The primary side switching circuit 11 and the LC resonant circuit 12 correspond to the "primary side switching circuit" of the present invention.

The primary side switching circuit 11 is composed of a full bridge circuit or a half bridge circuit including multiple switching elements. The switching elements may be power semiconductor switching elements such as IGBTs (insulated gate bipolar transistors), MOSFETs (metal oxide semiconductor field effect transistors), SiC (silicon carbide)-MOSFETs, and GaN (gallium nitride)-MOSFETs. In the current path of the switching elements, diodes (including built-in diodes) are connected in parallel in the reverse direction, and a capacitor is connected in parallel.

The LC resonant circuit 12 is part of the primary switching circuit and is composed of a resonant coil and a resonant capacitor. In this embodiment, the LC resonant circuit 12 further includes an excitation coil to form an LLC type resonant circuit. The resonance coil can be composed of a leakage inductance of the isolation transformer 13 in part or in whole, and the excitation coil can be composed of the excitation inductance of the isolation transformer 13. The LC resonant circuit 12 may be included in the primary switching circuit 11.

The isolation transformer 13 is a high-frequency isolation transformer including a primary coil and a secondary coil. The primary coil is connected to the primary switching circuit 11 via the LC resonant circuit 12, and the secondary coil is connected to the secondary rectifier circuit 14. The isolation transformer 13 may be composed of one or more high-frequency isolation transformers depending on the capacity.

The secondary rectifier circuit 14 is composed of a rectifier circuit including a diode and a smoothing circuit including a capacitor. The rectifier circuit may be a synchronous rectifier circuit composed of switching elements. The synchronous rectifier circuit is, for example, a full-bridge connection of switching elements such as power semiconductors, and each switching element is turned on/off by synchronous rectification control depending on the state of the primary switching circuit 11 and the voltage or current state of the secondary rectifier circuit 14.

The control unit 20A includes an output current detection unit 21, a first calculation unit 22, a first PI control unit 23, a current ripple extraction unit 24, a rectification unit 25, a second calculation unit 26, a second PI control unit 27, an input voltage ripple extraction unit 28, a multiplier 29, a third calculation unit 30, and a pulse generation unit 31. When the secondary side rectification circuit 14 performs synchronous rectification, the control unit 20A detects the current or voltage of the secondary side rectification circuit 14 and performs on/off control of the switching element for synchronous rectification in accordance with the switching state of the primary side switching circuit 11.

The output current detection unit 21, the first calculation unit 22, and the first PI control unit 23 correspond to the "first control unit" of the present invention. The current ripple extraction unit 24, the rectification unit 25, the second calculation unit 26, and the second PI control unit 27 correspond to the "gain generation unit" of the present invention. The input voltage ripple extraction unit 28 and the multiplier 29 correspond to the "second control unit" of the present invention. The third calculation unit 30 and the pulse generation unit 31 correspond to the "third control unit" of the present invention.

The output current detection unit 21 detects the output current output from the secondary side rectifier circuit 14 and outputs a signal related to the detected current value to the first calculation unit 22 and the current ripple extraction unit 24.

The first calculation unit 22 calculates the difference between the current value of the output current input from the output current detection unit 21 and a target value (in this embodiment, the target value of the output current) input from outside (e.g., a higher-level device). The first calculation unit 22 outputs a signal related to the calculated difference to the first PI control unit 23.

The first PI control unit 23 generates a "first control command value" that brings the difference closer to zero by a PI (proportional integral) calculation based on the difference calculated by the first calculation unit 22. The first PI control unit 23 outputs the generated first control command value to the third calculation unit 30.

The current ripple extraction unit 24 extracts ripple noise (output current ripple) contained in the output current detected by the output current detection unit 21. The current ripple extraction unit 24 is composed of a bandpass filter that combines, for example, an LPF (low pass filter) and an HPF (high pass filter).

The rectifier 25 rectifies the output current ripple extracted by the current ripple extraction unit 24. Specifically, the rectifier 25 extracts the DC component of the absolute value of the output current ripple. The rectifier 25 may be included in the current ripple extraction unit 24.

The second calculation unit 26 calculates the difference between the output current ripple rectified by the rectification unit 25 and a ripple target value (corresponding to the "predetermined value" of the present invention). The ripple target value is a target value of the peak-to-peak current value of the output current ripple, and in this embodiment, is set to 0 [App]. The second calculation unit 26 outputs a signal related to the calculated difference to the second PI control unit 27.

The second PI control unit 27 generates a current gain that brings the difference closer to zero by a PI (proportional integral) calculation based on the difference calculated by the second calculation unit 26. The second PI control unit 27 outputs the generated current gain to the multiplier 29.

The input voltage ripple extraction unit 28 extracts ripple noise (input voltage ripple) contained in the input voltage. The input voltage ripple extraction unit 28 is composed of a bandpass filter that combines an LPF (low pass filter) and an HPF (high pass filter), for example.

The multiplier 29 multiplies the input voltage ripple extracted by the input voltage ripple extraction unit 28 by the current gain input from the second PI control unit 27 to generate a "second control command value." The multiplier 29 outputs the generated second control command value to the third calculation unit 30.

The third calculation unit 30 adds the first control command value input from the first PI control unit 23 and the second control command value input from the multiplier 29 to generate a "third control command value" and outputs the third control command value to the pulse generation unit 31.

The pulse generating unit 31 generates switching pulses for turning on/off the switching elements included in the primary side switching circuit 11 based on the third control command value, and outputs the switching pulses to the primary side switching circuit 11. When performing synchronous rectification control in the secondary side rectifier circuit 14, the pulse generating unit 31 acquires necessary information from the secondary side in addition to the state of the primary side switching circuit 11, generates switching pulses for turning on/off the switching elements included in the secondary side rectifier circuit 14, and outputs the switching pulses to the secondary side rectifier circuit 14.

Figure 3(A) shows an example of a waveform diagram of the input voltage ripple and output current ripple in a conventional DC/DC converter, and Figure 3(B) shows an example of a waveform diagram of the input voltage ripple and output current ripple in the DC/DC converter 2A according to this embodiment. Note that the units of the voltage scale are the same in both cases, but the units of the current scale are 2 [A/div] in Figure 3(A) and 0.4 [A/div] in Figure 3(B).

The conventional DC/DC converter has a configuration similar to that of the DC/DC converter 2A according to this embodiment, except that the gain generation unit (current ripple extraction unit 24, rectification unit 25, second calculation unit 26, and second PI control unit 27) and the second control unit (input voltage ripple extraction unit 28 and multiplier 29) are removed.

In Figures 3(A) and 3(B), in a conventional DC/DC converter and DC/DC converter 2A according to this embodiment, an input voltage ripple of 300 [Hz]/10 [Vpp] is superimposed on an input voltage of 450 [V], the output voltage is 400 [V], and the target value of the output current is 31 [A].

As shown in Fig. 3(A), the output current ripple is 4 [App] in a conventional DC/DC converter, whereas as shown in Fig. 3(B), the output current ripple is reduced to 0.4 [App] in the DC/DC converter 2A according to this embodiment. The CHAdeMO standard specifies that the ripple noise of a quick charger must be less than 3 [App], but as shown above, the DC/DC converter 2A according to this embodiment has a value of 0.4 [App], which is much smaller than the specified value.

In this way, the DC/DC converter 2A according to this embodiment generates a current gain for keeping the output current ripple below a predetermined value, and feed-forward controls the input voltage ripple using this current gain, so that the output current ripple can be reduced to about one-tenth of that of conventional DC/DC converters.

Furthermore, in the DC/DC converter 2A of this embodiment, low-frequency ripple noise can be reduced even if the cutoff frequency of the filter circuit 4 provided in the upstream stage is increased, so that the filter circuit 4 can be made smaller, less expensive, and lighter.
[Second embodiment]
FIG. 4 shows an example of a block diagram of a power supply device 1B according to a second embodiment of the present invention, and FIG. 5 shows an example of a block diagram of a DC/DC converter 2B according to the second embodiment of the present invention.

As shown in FIG. 4, the power supply device 1B has the same configuration as the first embodiment, except for the DC/DC converter 2B. As shown in FIG. 5, the DC/DC converter 2B is composed of a power conversion unit 10 and a control unit 20B. The power conversion unit 10 has the same configuration as the first embodiment.

The control unit 20B has the same configuration as the first embodiment in the first control unit (output current detection unit 21, first calculation unit 22, and first PI control unit 23) and the third control unit (third calculation unit 30 and pulse generation unit 31), but has different configurations from the first embodiment in the gain generation units K, L, and M and the second control unit (input voltage ripple extraction units 28K, 28L, and 28M and multipliers 29K, 29L, and 29M).

Gain generation unit K generates a current gain K for reducing the output current ripple of the Kth frequency to a predetermined value or less, gain generation unit L generates a current gain L for reducing the output current ripple of the Lth frequency to a predetermined value or less, and gain generation unit M generates a current gain M for reducing the output current ripple of the Mth frequency to a predetermined value or less.

The gain generating units K, L, and M are respectively composed of current ripple extracting units 24K, 24L, and 24M, rectifying units 25K, 25L, and 25M, second calculating units 26K, 26L, and 26M, and second PI control units 27K, 27L, and 27M. Each configuration is the same as in the first embodiment, except that it corresponds to the Kth, Lth, and Mth frequencies, respectively.

For example, the current ripple extraction unit 24K is configured with a bandpass filter through which the output current ripple of the Kth frequency passes, the current ripple extraction unit 24L is configured with a bandpass filter through which the output current ripple of the Lth frequency passes, and the current ripple extraction unit 24M is configured with a bandpass filter through which the output current ripple of the Mth frequency passes.

The second control unit is the same as in the first embodiment, except that it corresponds to the Kth, Lth, and Mth frequencies. Input voltage ripple extraction units 28K, 28L, and 28M extract input voltage ripples of the Kth, Lth, and Mth frequencies, respectively. Multipliers 29K, 29L, and 29M multiply the input voltage ripples of the Kth, Lth, and Mth frequencies by the current gains K, L, and M, which are the outputs of the Kth, Lth, and Mth gain generation units K, L, and M, respectively, to generate "second control command values K, L, and M".

The third calculation unit 30 adds the first control command value input from the first PI control unit 23 to the second control command values K, L, and M input from the multipliers 29K, 29L, and 29M to generate a "third control command value" and outputs the third control command value to the pulse generation unit 31.

The DC/DC converter 2B according to this embodiment generates current gains K, L, and M for reducing the output current ripples of the Kth, Lth, and Mth frequencies to a predetermined value or less, and feed-forward controls the input voltage ripples of the Kth, Lth, and Mth frequencies using the current gains K, L, and M. Therefore, the DC/DC converter 2B according to this embodiment can more accurately reduce the output current ripples of the Kth, Lth, and Mth frequencies.

Furthermore, in the DC/DC converter 2B according to this embodiment, as in the first embodiment, low-frequency ripple noise can be reduced even if the cutoff frequency of the filter circuit 4 provided in the upstream stage is increased, so that the filter circuit 4 can be made smaller, less expensive, and lighter.

[Modification]
Although the embodiments of the DC/DC converter and the power supply device according to the present invention have been described above, the present invention is not limited to the above-mentioned embodiments.

In the above embodiment, a DC/DC converter has been described that includes a primary switching circuit including a switching element that switches an input voltage, an isolation transformer, a secondary rectifier circuit connected to the primary switching circuit via the isolation transformer, and a control unit that controls the primary switching circuit (the primary switching circuit and the secondary rectifier circuit when the secondary rectifier circuit is synchronous rectifier). The control unit includes a first control unit that generates a first control command value for bringing at least one of the output current and the output voltage output from the secondary rectifier circuit closer to a predetermined target value, a gain generation unit that extracts an output current ripple contained in the output current and generates a gain for making the output current ripple equal to or less than a predetermined value, a second control unit that extracts an input voltage ripple contained in the input voltage input to the primary switching circuit and generates a second control command value based on the input voltage ripple and the gain, and a third control unit that controls the switching element based on the first control command value and the second control command value. However, the configuration can be changed as appropriate without being limited to this.

For example, in the above embodiment, the output current ripple has been described, but the same applies to the output voltage ripple. That is, in the case of the output voltage ripple, instead of the output current detection in the output current detection unit 21, the output voltage detection unit detects the output voltage, and instead of the output current ripple extraction in the current ripple extraction unit 24, the output voltage ripple is extracted by the voltage ripple extraction unit. The voltage ripple extraction unit extracts the output voltage ripple contained in the output voltage, and the gain generation unit generates a gain to keep the output voltage ripple below a predetermined value.

The DC/DC converter according to the present invention may be a current resonant DC/DC converter of the CLLLC or CLLLC type capable of bidirectional operation, or may be a current resonant DC/DC converter of another type, or may be a voltage-current type DC/DC converter, a DAB (Dual Active Bridge) type DC/DC converter, etc.

The power supply device according to the present invention can be modified as appropriate as long as it includes an AC/DC converter, a filter circuit provided on the DC end side of the AC/DC converter, and a DC/DC converter according to the present invention connected to the AC/DC converter via the filter circuit. For example, the power supply device according to the present invention may include multiple DC/DC converters, or multiple power supply units each consisting of an AC/DC converter, a filter circuit, and a DC/DC converter. In addition, part or all of the filter circuit may be included in the AC/DC converter or the DC/DC converter. In addition, the power supply device may be an integrated AC/DC converter and DC/DC converter.

The control unit of the present invention may be configured with each component as a hardware circuit, or at least a part of each component may be configured as a software circuit that performs software processing on a microprocessor or the like. For example, in the first embodiment, the output of the output current detection unit 21, the output of the input voltage ripple extraction unit 28, and the output of the rectification unit 25 may be A/D converted and read by a microprocessor or the like, the remaining processing may be performed by software, and the output of the pulse generation unit 31 may be D/A converted to output a switching pulse as a PWM signal to the primary side switching circuit 11. The same applies to the second embodiment.

In the second embodiment, a single ripple target value was used to generate the current gains K, L, and M for the output current ripples of the Kth, Lth, and Mth frequencies, but a ripple target value may be set individually for the output current ripple of each frequency to generate the current gains K, L, and M.

DESCRIPTION OF SYMBOLS 1A, 1B Power supply devices 2A, 2B DC/DC converter 3 AC/DC converter 4 Filter circuit 5 AC power supply 6 Battery 10 Power conversion section 11 Primary side switching circuit 12 LC resonant circuit 13 Isolation transformer 14 Secondary side rectifier circuit 20A, 20B Control section 21 Output current detection section 22 First calculation section 23 First PI control section 24, 24K to 24M Current ripple extraction section 25, 25K to 25M Rectification section 26, 26K to 26M Second calculation section 27, 27K to 27M Second PI control section 28, 28K to 28M Input voltage ripple extraction section 29, 29K to 29M Multiplier 30 Third calculation section 31 Pulse generation section

Claims (6)

a primary side switching circuit including a switching element that switches an input voltage;
An isolation transformer,
a secondary side rectifier circuit connected to the primary side switching circuit via the isolation transformer;
A control unit that controls at least the switching element;
A DC/DC converter comprising:
The control unit is
a first control unit that generates a first control command value for bringing an output from the secondary side rectifier circuit closer to a predetermined target value;
a gain generating unit that extracts an output ripple included in an output from the secondary side rectifier circuit and generates a gain for making the output ripple equal to or smaller than a predetermined value;
a second control unit that extracts an input voltage ripple included in the input voltage input to the primary side switching circuit, and generates a second control command value based on the input voltage ripple and the gain;
a third control unit that controls the switching element based on the first control command value and the second control command value ,
the first control unit generates the first control command value so as to bring at least one of an output current and an output voltage output from the secondary side rectifier circuit closer to the predetermined target value;
The gain generating unit is
extracting an output current ripple contained in an output current output from the secondary side rectifier circuit as an output from the secondary side rectifier circuit, and generating a gain for making the output current ripple equal to or less than a predetermined value;
a current ripple extraction unit that extracts the output current ripple;
a rectification unit that rectifies the output current ripple;
a second calculation unit that calculates a difference between the output current ripple rectified by the rectification unit and the predetermined value;
a second PI control unit that generates the gain by a PI calculation based on the difference.
A DC/DC converter comprising: The first control unit is
an output current detection unit that detects a current value of the output current;
A first calculation unit that calculates a difference between the current value and the target value;
2. The DC/DC converter according to claim 1 , further comprising: a first PI control unit that generates the first control command value by a PI calculation based on the difference. The second control unit is
an input voltage ripple extraction unit that extracts the input voltage ripple;
3. The DC/DC converter according to claim 1, further comprising: a multiplier that multiplies the input voltage ripple by the gain to generate the second control command value. a primary side switching circuit including a switching element that switches an input voltage;
An isolation transformer,
a secondary side rectifier circuit connected to the primary side switching circuit via the isolation transformer;
A control unit that controls at least the switching element;
A DC/DC converter comprising:
The control unit is
a first control unit that generates a first control command value for bringing an output from the secondary side rectifier circuit closer to a predetermined target value;
a gain generating unit that extracts an output ripple included in an output from the secondary side rectifier circuit and generates a gain for making the output ripple equal to or smaller than a predetermined value;
a second control unit that extracts an input voltage ripple included in the input voltage input to the primary side switching circuit, and generates a second control command value based on the input voltage ripple and the gain;
a third control unit that controls the switching element based on the first control command value and the second control command value,
the gain generation unit generates N gains corresponding to the output ripples of N frequencies (N is an integer equal to or greater than 2);
the second control unit generates the N second control command values based on the input voltage ripples of the N frequencies and the N gains;
The DC/DC converter, wherein the third control unit controls the switching elements based on the first control command value and N second control command values. a primary side switching circuit including a switching element that switches an input voltage;
An isolation transformer,
a secondary side rectifier circuit connected to the primary side switching circuit via the isolation transformer;
A control unit that controls at least the switching element;
A DC/DC converter comprising:
The control unit is
a first control unit that generates a first control command value for making an output from the secondary side rectifier circuit approach a predetermined target value;
a gain generating unit that extracts an output ripple included in an output from the secondary side rectifier circuit and generates a gain for making the output ripple equal to or smaller than a predetermined value;
a second control unit that extracts an input voltage ripple included in the input voltage input to the primary side switching circuit, and generates a second control command value based on the input voltage ripple and the gain;
a third control unit that controls the switching element based on the first control command value and the second control command value,
the first control unit generates the first control command value so as to bring at least one of an output current and an output voltage output from the secondary side rectifier circuit closer to the predetermined target value;
The gain generating unit is
An output current ripple included in an output current output from the secondary side rectifier circuit is extracted as an output from the secondary side rectifier circuit, and a gain is generated for making the output current ripple closer to zero;
a current ripple extraction unit that extracts the output current ripple;
a rectification unit that rectifies the output current ripple;
a second PI control unit that generates the gain by a PI calculation based on the output current ripple rectified by the rectification unit.
A DC/DC converter comprising: An AC/DC converter;
A filter circuit provided on a DC end side of the AC/DC converter;
A power supply device comprising: a DC/DC converter according to any one of claims 1 to 5 , connected to the AC/DC converter via the filter circuit.

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