RESONANCE POWER SUPPLY DEVICE

Abstract

Resonant power supply device (101) comprising the following: a main power supply circuit (102) comprising a transformer (107), a resonant element (106) connected to a primary side of the transformer (107), and several switching elements (105a, ..., 105d) connected to the resonant element (106); and a power supply control circuit (103) that switches the several switching elements (105a, ..., 105d) in the main power supply circuit (102) at a predetermined switching frequency, wherein the power supply control circuit (103) includes the following: a voltage control unit (202) which outputs a current command value from a reference voltage, an output voltage of the main power supply circuit (102) and a voltage control gain; wherein the voltage control unit (202) performs arithmetic processing such that the current command value decreases when the output voltage is greater than the reference voltage, and increases when the output voltage is less than the reference voltage; a current control unit (203) which calculates the switching frequency from the current command value, an output current flowing on a secondary side of the transformer (107), and a current control gain; wherein the current control unit (203) performs arithmetic processing such that the switching frequency increases when the output current is greater than the current command value, and decreases when the output current is less than the current command value; a gain calculation unit (504) that outputs the voltage control gain and the current control gain; and a control signal generator (113) which, based on the switching frequency output by the current control unit (203), controls several switching elements (105a, ..., 105d), wherein the gain calculation unit (504) outputs the voltage control gain or the current control gain which are proportional to the switching frequency output by the current control unit (203).

Description

Technical field

[0001] The present invention relates to a resonant current supply device. Background area

[0002] A resonant power supply is used, for example, in industrial plants, data processing systems, and similar applications. The resonant power supply incorporates an LLC current resonant circuit. This circuit utilizes a resonance phenomenon to generate a sinusoidal current and switches off a switching element when the current becomes low. This results in a highly efficient resonant power supply with minimal switching losses.

[0003] Such a resonant current supply device sets a switching frequency to control an output voltage. However, if the ratio of an input voltage to the output voltage within a specification range (hereinafter referred to as the "input / output voltage ratio") covers an extended range due to characteristics of the LLC current resonant circuit, power supply characteristics may degrade due to control gain with respect to the output voltage.

[0004] In contrast, patent document 1 discloses a device that can prevent a deterioration of the power supply characteristics by setting a proportional gain of a voltage value of an output voltage and an error of a reference voltage source.

[0005] According to patent document 1, a switching power supply 1, comprising an LLC current resonant circuit and switching elements Q1 and Q2, detects a deviation between the output voltage and a setpoint of the output voltage, determined by a supply voltage of the reference voltage source Vref, and passes a current, dependent on the detection result, through a phototransistor PC2. Furthermore, a control circuit controls the proportional gain depending on an oscillation frequency of the switching power supply and controls the on / off frequencies of the switching elements Q1 and Q2 based on the controlled proportional gain and a voltage at a terminal P1. This configuration prevents fluctuations in the proportional gain depending on fluctuations in the input voltage.

[0006] Patent document 2 describes a control device for use with a power converter and a method for operating the same. In one embodiment, the control device includes a circuit for sensing the transformer voltage, configured to generate a preliminary bus voltage sample. The control device also includes a frequency correction circuit coupled to the transformer voltage sensing circuit and configured to correct the preliminary bus voltage sample to generate an estimate of the power converter's internal bus voltage.

[0007] Patent document 3 describes a resonant power conversion device and a control method for the resonant power conversion device. The resonant power conversion device comprises a switchable resonant converter and a controller. The switchable resonant converter is configured to supply power to a load. The controller is coupled to the switchable resonant converter and the load and is configured to control the switching of the switchable resonant converter in order to regulate the power conversion of the switchable resonant converter. The controller has a voltage control loop and a current control loop. The controller detects a drive state of the load and activates either the voltage control loop or the current control loop according to the detection result to set a switching frequency of the switchable resonant converter.

[0008] The non-patent literature 1 describes a digital master-slave controlled parallel system consisting of several LLC resonant converters with an internal resonant current control loop in each module.

[0009] Non-patent literature 2 describes a gain control using a voltage-controlled oscillator with variable gain for an LLC resonant converter to improve dynamic performance. Documents of the related field: Patent documents Patent document 1: JP 2014 - 54 038 A Patent document 2: US 2015 / 0 198 634 A1 Patent document 3: US 2015 / 0 109 830 A1 Non-Patent Literature 1: Sheng Zong et al. “Theoretical Evaluation of Stability Improvement Brought by Resonant Current Loop for Paralleled LLC Converters”; IEEE Transactions on Industrial Electronics, Vol. 62, 2015, Issue 7, 4170-4180. Non-Patent Literature 2: Sang Woo Kang et al. “Gain-scheduled control using voltage controlled oscillator with variable gain for an LLC resonant converter”; IEEE Energy Conversion Congress and Exposition (ECCE), 2014, 4466-4471 Summary of the invention Problems to be solved by the invention

[0010] Patent document 1 discloses that the switching power supply described in patent document 1 controls the proportional gain depending on an oscillation frequency of an error voltage between the voltage value of the output voltage and the setpoint of the output voltage, which is determined by the supply voltage of the reference voltage Vref.

[0011] However, controlling the proportional gain based on the oscillation frequency of the fault voltage means that the proportional gain is reduced after an oscillation occurs and increased when the oscillation stops. Consequently, such a problem cannot be solved by providing a stable power supply without generating the highest possible oscillation in the output voltage from the outset. Means of solving the problems

[0012] A brief description of typical inventions disclosed in the present application is as follows.

[0013] A resonant power supply device according to a typical embodiment of the present invention comprises: a power supply main circuit comprising a transformer, a resonant element connected to a primary side of the transformer, and several switching elements connected to the resonant element; and a power supply control circuit that switches the several switching elements in the power supply main circuit at a predetermined switching frequency, wherein the power supply control circuit comprises: a voltage control unit that outputs a current command value from a reference voltage, an output voltage of the power supply main circuit, and a voltage control gain; a current control unit that calculates a reference current, a current flowing on a secondary side of the transformer, and a current control gain;a gain calculation unit that outputs the voltage control gain and the current control gain; and a control signal generator that, based on the switching frequency output by the current control unit, controls several switching elements, and the gain calculation unit outputs the voltage control gain or the current control gain proportional to the switching frequency output by the current control unit.

[0014] The underlying problem is solved by the attached claim 1 and preferred further developments are described by the dependent claims. Effects of the invention

[0015] According to a typical embodiment of the present invention, it is possible to suppress the oscillation of the output voltage and to improve the power supply characteristics. Brief description of the drawings Fig. Figure 1 is a view showing an example of a configuration of a resonant power supply device according to an embodiment that applies the present invention; Fig. Figure 2 is a view showing an example of a control block of a control variable calculation unit according to an embodiment that applies the present invention; Fig. 3(a) is a view showing examples of a voltage, a current and a switching frequency process when a control gain is a constant value; Fig. 3(b) is a view that provides examples of a voltage, a current, and a switching frequency process when the control gain is a constant value and has a value greater than that from Fig. 3(a) is, shows; Fig. 4(a) is a view showing an example of a relationship between the magnitude of the switching frequency change and the magnitude of the output current in the resonant power supply device; Fig. 4(b) is a view showing a relationship between the control gain and a switching frequency in the resonant power supply device; Fig. Figure 5 is a view showing a relationship between a control gain and a switching frequency at each of three points in the resonant power supply device; Fig. Figure 6 is a diagram to explain a modification example of a control gain calculation unit according to an embodiment that applies the present invention; Fig. Figure 7 is a view showing a waveform example when using the control gain calculation unit according to the embodiment employing the present invention; Fig. Figure 8 is a view showing an example of a configuration of a resonant power supply device according to a second embodiment of the present invention; Fig. Figure 9 is a diagram to explain a control gain calculation unit of the resonant current supply device according to the second embodiment of the present invention; Fig. Figure 10 is a view showing an example of a configuration of a resonant power supply device according to a third embodiment of the present invention; Fig. Figure 11 is a view showing an example of a configuration of a resonant power supply device according to a fourth embodiment of the present invention; Fig. Figure 12(a) is a view showing a relationship between a circuit gain M and a switching frequency according to a fifth embodiment of the present invention, wherein the circuit gain M is calculated from the number of windings on a primary and a secondary side of a transformer, an input voltage and an output voltage; and Fig. Figure 12(b) is a view showing a relationship between a control gain and a circuit gain M according to the fifth embodiment of the present invention. Detailed description of the preferred embodiments

[0016] In the following, embodiments of the present invention are described in detail with reference to the drawings. For the purpose of explaining the embodiments, the same components are designated with the same reference numerals in all figures, and repeated descriptions thereof are omitted. (First embodiment)<Konfiguration der Resonanzstromversorgungseinrichtung> <<Konfiguration der Stromversorgungshauptschaltung> >

[0017] Fig. Figure 1 is a view showing an example of a configuration of a resonant power supply device according to a first embodiment employing the present invention. As shown in Fig. As shown in Figure 1, a resonant power supply device 101 includes a main power supply circuit 102 and a power supply control circuit 103. The resonant power supply device 101 converts a voltage input from an externally provided input power supply 114 into a predetermined voltage and outputs the converted voltage to a load 115.

[0018] A high-potential end section of the input power supply 114 is connected to an input terminal P1 of the main power supply circuit 102, which will be described later, and a low-potential end section of the input power supply 114 is the other input terminal P2 of the main power supply circuit 102. The high-potential and low-potential end sections of the load 115 are connected to the output terminals P3 and P4, respectively, of the main power supply circuit 102.

[0019] As in Fig. As shown in Figure 1, the main power supply circuit 102 includes an input-side capacitor 104, a primary-side semiconductor element 105, a resonant element 106, a transformer 107, a secondary-side semiconductor element 108 and an output-side capacitor 109.

[0020] The input capacitor 104 is a capacitor for absorbing a voltage ripple. As in Fig. As shown in Figure 1, a pair of electrodes of the input-side capacitor 104 is each connected to the input terminals P1 and P2 of the main power supply circuit 102. A predetermined input voltage Vin is applied to the input-side capacitor 104 by the input power supply 114.

[0021] The primary-side semiconductor element 105 switches a voltage applied to the resonant element 106 at a predetermined switching frequency. As shown in Fig. As shown in Figure 1, the primary-side semiconductor element 105 is composed of several switching elements 105a to 105d, each of which consists of a MOSFET such as an NMOS (N-channel MOS). As shown in Fig. As shown in Figure 1, these switching elements 105a to 105d are connected in a bridge form.

[0022] For example, one end section of switching element 105a and one end section of switching element 105c are connected to one input terminal P1 of the main power supply circuit 102, as shown in Fig. Figure 1 shows the following. One end section of switching element 105b and one end section of switching element 105d are connected to the other input terminal P2 of the main power circuit 102. The other end section of switching element 105a and the other end section of switching element 105b are connected to a resonant inductor 106a of the resonant element 106, which will be described later. The other end section of switching element 105c and the other end section of switching element 105d are connected to a resonant capacitor 106b of the resonant element 106. The gates of switching elements 105a to 105d are each connected to a switching control signal generator 113, which will be described later.

[0023] The switching control signals Vg1 to Vg4, output by the power supply control circuit 103, are each input into the gates of the switching elements 105a to 105d. The switching elements 105a to 105d are switched on and off based on their corresponding switching control signals Vg1 to Vg4. If the switching element is, for example, constructed from an NMOS, it assumes an on state (switched on) when a high-level switching control signal is input to the gate. Conversely, if a low-level switching control signal is input to the gate, the switching element assumes an off state (switched off).

[0024] The switching elements 105a to 105d are repeatedly switched on and off based on the switching control signals Vg1 to Vg4, injecting a pulsed voltage into the resonant element 106. For example, when switching elements 105a and 105d are in the ON states and switching elements 105b and 105c are in the OFF states, a predetermined voltage (Vin) is injected into the resonant element 106. Conversely, when switching elements 105a and 105d are in the OFF states and switching elements 105b and 105c are in the ON states, a predetermined voltage (-Vin) is injected into the resonant element 106. By repeating these processes, a pulsed voltage with a predetermined amplitude (Vin) is injected into the resonant element 106.

[0025] As in Fig. As shown in Figure 1, the resonant element 106 contains a resonant inductor 106a and a resonant capacitor 106b. As shown in Fig. As shown in Figure 1, one end section of the resonant inductor 106a is connected to the other end section of the switching element 105a and the other end section of the switching element 105b. Furthermore, as shown in Figure 1, one end section of the resonant inductor 106a is connected to the other end section of the switching element 105a and the other end section of the switching element 105b. Fig. As shown in Figure 1, the other end section of the resonant inductor 106a is connected to the transformer 107 via an input terminal P11 of the transformer 107.

[0026] As in Fig. As shown in Figure 1, one end section of the resonant capacitor 106b is connected to the transformer 107 via the other input terminal P12 of the transformer 107. Furthermore, as shown in Fig. As shown in Figure 1, the other end section of the resonant capacitor 106b is connected to the other end section of the switching element 150c and the other end section of the switching element 105d.

[0027] The resonant inductor 106a and the resonant capacitor 106b are connected in series. Furthermore, it is assumed that the resonant inductance Lr of the resonant inductor 106a contains a leakage inductance (not shown) of the transformer 107. The resonant inductance and the leakage inductance are related in series.

[0028] In Fig. In Figure 1, the resonant inductor 106a and the resonant capacitor 106b are arranged separately via the transformer 107, but are not limited to such an arrangement. For example, the resonant inductor 106a and the resonant capacitor 106b can be located on one side of the resonant inductor 106a, which is in Fig. The components shown in Figure 1 can be arranged on one side of the resonant capacitor 106b. The pulsed voltage described above is applied to the resonant element 106 from the primary-side semiconductor element 105. When the pulsed voltage is applied, a sinusoidal current with a resonant frequency Fo, defined on the basis of the resonant inductance Lr and the resonant capacitance Cr, flows through the resonant element 106 and the transformer 107.

[0029] As in Fig. As shown in Figure 1, the number of windings of a primary-side coil in transformer 107 is N1, the number of windings of a secondary-side coil is N2, and the output inductance is Lm. Transformer 107 converts the input voltage Vin, which is fed into the primary side via the resonant element 106, into a predetermined output voltage (Vo) on the secondary side and outputs the converted output voltage (Vo) outside the main power supply circuit 102.

[0030] The secondary-side semiconductor element 108 is an element that rectifies a current on the secondary side of the transformer 107. As shown in Fig. As shown in Figure 1, the secondary-side semiconductor element contains several diodes 108a to 108d. As shown in Fig. As shown in Figure 1, these diodes 108a to 108d are connected in a bridge configuration. For example, an anode-side end section of diode 108a and a cathode-side end section of diode 108b are connected to one output terminal P13 of transformer 107, as shown in Figure 1. Fig. Figure 1 shows that an anode-side end section of diode 108c and a cathode-side end section of diode 108d are connected to the other output terminal P14 of transformer 107, as shown in Figure 1. Fig. 1 is shown.

[0031] As in Fig. As shown in Figure 1, a cathode-side end section of diode 108a and a cathode-side end section of diode 108c are connected to an electrode of the output-side capacitor 109 and to one output terminal P3 of the main power supply circuit 102. An anode-side end section of diode 108b and an anode-side end section of diode 108d are connected to the other electrode of the output-side capacitor 109 and to the other output terminal P4 of the main power supply circuit 102, as shown in Figure 1. Fig. 1 is shown.

[0032] If the voltage at output terminal P13 is higher than the voltage at output terminal P14, a current on the secondary side of transformer 107 is rectified by diodes 108a and 108d. Conversely, if the voltage at output terminal P14 is higher than the voltage at output terminal P13, a current on the secondary side of transformer 14 is rectified by diodes 108c and 108b.

[0033] The output-side capacitor 109 is used to stabilize the output voltage. The main power supply circuit 102 detects a voltage between the two electrodes of the output-side capacitor 109 (voltage between output terminals P3, P4) as an output voltage (Vo) and outputs information about the detected output voltage (Vo) to the power supply control circuit 103. Furthermore, the main power supply circuit 102 outputs the output voltage (Vo) to the load 115 via output terminals P3, P4.

[0034] The main power supply circuit 102 detects an output current IL flowing through the main power supply circuit 102 and outputs information about the detected output current IL to a power supply control block 103. Furthermore, in an example described in Fig. Figure 1 shows the current flowing through the secondary-side semiconductor element 108 as the output current IL, however, for example, a current flowing through the resonant element 106 and / or the primary-side semiconductor element 105 can be detected as the output current IL. <<Konfiguration der Stromversorgungssteuerschaltung> >

[0035] As in Fig. As shown in Figure 1, a power supply control block 103 contains a control variable calculation circuit 111, a setting unit 112 for an upper / lower switching frequency limit and a switching control signal generator 113.

[0036] As in Fig. As shown in Figure 1, the following are entered into the control variable calculation block 103: information about the output voltage (Vo) detected by the main power supply circuit 102; a reference voltage (Vref), which is a setpoint of the output voltage (Vo); and an output current IL, which is detected by the main power supply circuit 102. The reference voltage (Vref) is entered by an external device. The external device can, for example, be located inside a device that includes the resonant power supply device 101, or it can be located outside a device that includes the resonant power supply device 101.

[0037] The control variable calculation circuit 111 calculates a switching frequency (Fsw) from the reference voltage (Vref), the input output voltage (Vo) and the output current IL, which is detected by the main power supply circuit 102, and inputs this into the setting unit 112 for an upper / lower switching frequency limit.

[0038] Furthermore, the control variable calculation circuit 111 determines a control variable required to adjust the output voltage (Vo) based on the output voltage (Vo) input from the main power supply circuit 102 and the reference voltage (Vref) input from the external device. The control variable is calculated such that the output voltage (Vo) is adjusted to the reference voltage (Vref).

[0039] The setting unit 112 for an upper / lower switching frequency limit adjusts the switching frequency (Fsw) output by the control variable calculation circuit 111 such that it falls within a range from a lower switching frequency limit (Fsw_min) to an upper switching frequency limit (Fsw_max). For example, if the switching frequency (Fsw) is greater than the upper switching frequency limit (Fsw_max), the setting unit 112 adjusts the switching frequency (Fsw) to the upper switching frequency limit (Fsw_max). If the switching frequency (Fsw) is less than the lower switching frequency limit (Fsw_min), the setting unit 112 adjusts the switching frequency (Fsw) to the lower switching frequency limit (Fsw_min).

[0040] The lower switching frequency limit (Fsw_min) and the upper switching frequency limit (Fsw_max) are preset values.

[0041] The switching control signal generator 113 generates the switching control signals Vg1 to Vg4 for each of the switching elements 105a to 105d based on the switching frequency (Fsw) output by the setting unit 112 for an upper / lower switching frequency limit.

[0042] For example, the switching control signal generator 113 generates the switching control signals Vg1 to Vg4 for each of the switching elements 105a to 105d based on the newly set switching frequency (Fsw). In this way, a control for setting the output voltage (Vo) solely by the switching frequency (Fsw) can be called frequency control. <Einstellung der Schaltfrequenz>

[0043] The operation of a control variable calculation unit 111, which calculates the switching (Fsw), is then described.

[0044] Fig. Figure 2 is a control block diagram in the control variable calculation unit 111 of the resonant current supply device that applies the present invention.

[0045] A voltage control unit 202 calculates a voltage difference (ΔV) between the output voltage (Vo) and the reference voltage (Vref) and calculates a current command (Iref) from the calculated voltage difference (ΔV) and a voltage control gain (AVRGainset). The voltage control gain (AVRGainset) is output by a control gain calculation unit 504. Details of the control gain calculation unit 504 are described later.

[0046] If the output voltage (Vo) is greater than the reference voltage (Vref), the voltage control unit 202 performs arithmetic processing such that the current command to be output (Iref) becomes smaller. If the output voltage (Vo) is less than the reference voltage (Vref), the voltage control unit 202 performs arithmetic processing such that the current command to be output (Iref) becomes larger.

[0047] A current control unit 203 calculates a current difference (ΔI) between the current command (Iref) issued by the voltage control unit 202 and the output current (IL) flowing through the power supply main circuit 102. From this calculated current difference (ΔI) and a current control gain (ACRGainset), the switching frequency (Fsw) is calculated. The current control gain (ACRGainset) is output by the control gain calculation unit 504. Details of the control gain calculation unit 504 are described later.

[0048] If the output current (IL) is greater than the current command (Iref), the current control unit 203 performs arithmetic processing such that the output switching frequency (Fsw) becomes high in order to prevent current from being supplied to the output capacitor 109. Conversely, if the output current (IL) is less than the current command (Iref), the current control unit 203 performs arithmetic processing such that the output switching frequency (Fsw) becomes lower in order to increase the current supplied to the output capacitor.

[0049] The voltage characteristics resulting from the control gain in the resonant current supply device are then described. The control gain, referred to here, is a control variable for each control unit. When the control gain refers to the voltage control unit, the control gain is AVRGain. When the control gain refers to the current control unit, the control gain is ACRGain. For brevity, these are combined and referred to as the "control gain."

[0050] Fig. Figure 3(a) shows a fluctuation in the output voltage Vo when the control gain is set to a specific constant value. For example, if the current flowing through the load 115 suddenly changes, the electrical charge in the output capacitor 109 decreases, causing the output voltage Vo to become small. When the output voltage Vo fluctuates, a current control circuit controls the output voltage Vo to follow the reference voltage (Vref). However, because the control gain is low, the response until the switching frequency changes from Fsw_A to Fsw_B is slow. That is, when the control gain is low, the rate of change of the switching frequency per unit time is small, and the fluctuation in the output voltage Vo becomes large.

[0051] Since the control gain value in Fig. 3(b) higher than that in Fig. 3(a) is a fast response until the switching frequency is changed to Fsw_B. That is, if the control gain is high, the rate of change of the switching frequency per unit time is large and the fluctuation of the output voltage Vo becomes small. However, since the control gain is higher than that in Fig. 3(a) is, the output voltage Vo is not stable under a constant load and can oscillate.

[0052] Fig. 4(a) is a view obtained by measuring a relationship between the switching frequency and the output current IL in the resonant power supply device whose gain is constant. Fig. Figure 4(a) shows that when the output current fluctuates by an output current fluctuation amount (ΔIL) from IL_A1 to IL_A2, the change in the switching frequency is ΔFsw_1. Furthermore, it shows Fig. 4(a) that when the output current fluctuates by the output current fluctuation amount (ΔIL) from IL_B1 to IL_B2, the change in the switching frequency is ΔFsw_2. For the same output current fluctuation amount (ΔIL), it can be seen that Fig. 4(a) exhibits a relationship of ΔFsw_2 < ΔFsw_1.

[0053] According to Fig. 4(a) The switching frequency range is large when the output current IL fluctuates in a small state, such that a large control gain is required. Conversely, when the output current IL fluctuates in a large state, the switching frequency range is small, such that a small control gain is sufficient. This relationship also applies to the voltage.

[0054] Fig. Figure 4(b) is a relationship diagram in which a horizontal axis is the switching frequency Fsw and a vertical axis is the control gain Gain, which is set by the control variable calculation unit 111. The appropriate control gain for the lower switching frequency limit (Fsw_min) is Gain_B, and the appropriate control gain for the upper switching frequency limit (Fsw_min) is Gain_A. As shown in Figure 4(b), the control gain is set by the control variable calculation unit 111. Fig. As can be seen in Figure 4(a), it is shown that the appropriate control gain also increases when the switching frequency (Fsw) increases.

[0055] With renewed reference to Fig. Section 2 describes the control gain calculation unit 504. The control gain calculation unit 504 is a block that sets the values ​​of the voltage control gain and the current control gain each time by using the relationship between the switching frequency and the control gain, which is given in Fig. 3 and Fig. 4 is described.

[0056] In particular, the control gain calculation unit 504 calculates preset output values ​​(AVRGain, ACRGain) of the voltage control gain and the current control gain, such that the control gain varies according to the switching frequency, and outputs these to the voltage control unit 202 and the current control unit 203.

[0057] For example, if it is desired to change the control gain linearly (according to a linear function), as in Fig. As shown in Figure 4(b), the control gain calculation unit stores as output values ​​the control gains corresponding to the lower switching frequency limit (Fsw_min) and the upper switching frequency limit (Fsw_min). The following relational expression (Equation 1) is derived from these four values. Gain=α∗Fsw+β

[0058] Here, a slope α of a graph and a constant β in (Equation 2) are shown. α=Gain_A−Gain_BFsw_max+Fsw_minβ=(Gain_B∗Fsw_max)−(Gain_A∗Fsw_min)Fsw_max−Fsw_min

[0059] Using a value from (Equation 2) changes (Equation 1) to (Equation 1'). Gain=(Gain_A−Gain_B)(Fsw_max−Fsw_max)(Fsw−Fsw_min)+Gain_B

[0060] Therefore, the control gain calculation unit 504 calculates a control gain by inputting a switching frequency Fsw immediately before it is output by a current converter 203, in (Equation 1'). In the explanation, the control gain mentioned above is a general term, and thus the control gain calculation unit 504 actually performs an operation on each (or only on one of them) of the voltage control gain (AVRGain) and the current control gain (ACRGain) and calculates a voltage control gain (AVRGain_set) and / or a current control gain (ACRGain_set).

[0061] In this embodiment, both the voltage control gain and the current control gain are calculated; however, only one of the gains can be calculated, while the other gain can be a constant value. Such configurations, to control both gains depending on the switching frequency, make it possible to further improve the stability of the output voltage Vo.

[0062] Furthermore, as in Fig. As shown in Figure 5, a relationship can be used between each of the switching frequencies of three or more points and each of the control gains of three or more points. This case can be implemented by switching (Equation 1') with a value of Fsw_mid as a limit.

[0063] Furthermore, the relationship between the switching frequency and the control gain can be proportional and need not necessarily be a linear function (straight line). For example, the control gain can be calculated by storing values ​​of the switching frequencies from three or more points and values ​​of the control gains from three or more points, and using a quadratic function or a higher-degree function obtained by the method of least squares or the like, instead of (Equation 1').

[0064] Furthermore, in this embodiment, the control gain is calculated by inputting the switching frequency Fsw immediately before it is output by the current converter 203; however, the switching frequency Fsw can be a value at the current time or earlier than immediately before (e.g., a few clock cycles prior). Additionally, the switching frequency Fsw can be a value obtained by performing a delay filter.

[0065] Alternatively, as in Fig. Figure 6 shows that the voltage control gains (AVRGainA to AVRGainE) and the current control gains (ACRGainA to ACRGainE) are pre-stored (backed up) and used as a table in a storage device according to the relationship between the switching frequency and the control gain.

[0066] Fig. Figure 6(a) shows a diagram in which the control gain increases stepwise according to the switching frequency. Here, each control gain is stored as a table, as in Fig. Figure 6(b) shows that the control gain calculation unit 504 selects a control gain depending on the switching frequency and outputs it to the voltage control unit 202 and the current control unit 203.

[0067] Fig. Figure 7 shows a voltage fluctuation waveform when the output voltage is controlled using a control variable calculation unit 511 of the present embodiment. When the output current (IL) flowing through the main power supply circuit 102 is small, the control gain is set high because the switching frequency is high.

[0068] Similar to in Fig. 3. The fluctuation of the output voltage is quickly changed to the switching frequency (Fsw_B) when the output current (IL) flowing through the main power supply circuit 102 suddenly increases significantly, due to the high control gain, such that the fluctuation of the output voltage Vo is suppressed to such an extent that it is smaller than that in the case of Fig. 3(a). Furthermore, the control gain also decreases as the switching frequency (Fsw) decreases, such that the output voltage Vo does not oscillate under a constant load, making it possible to obtain stable power supply characteristics.

[0069] As described above, changing the value of the control gain according to the switching frequency according to the embodiment used in the present invention prevents large fluctuations and oscillations of the output voltage Vo and makes it possible to maintain stable power supply characteristics.

[0070] Furthermore, the present invention is not limited to the embodiment described above and includes various modification examples. For example, the feedback control method can be a proportional (P) controller, a pi (PI) controller, or a proportional-indicator (PID) controller. In each case, a conversion coefficient or coefficients for the control gain can be multiplied by the final multiplication of the current control gain and / or the final multiplication of the voltage control gain.

[0071] Furthermore, the resonant current supply device of the present invention can be configured independently or can be incorporated into various devices such as control ICs together with other component elements.

[0072] The embodiment described above is an example to explain the concept of the present invention and is not necessarily limited to an embodiment or embodiments that include all the component elements described in the embodiment above. (Second embodiment)

[0073] A second embodiment of the present invention is then described. In the present embodiment, an example is shown in which the control is carried out without using the output current (IL) that is detected by the resonant current supply device 101 in each example of the embodiment described above.

[0074] A resonant power supply unit 801 performs the same processing as those in Fig. 1 through, but detects a voltage between both electrodes of an output-side capacitor 809 (voltage between the output terminals P3, P4) as the output voltage (Vo) and outputs information about the detected output voltage (Vo) to a power supply control block 803.

[0075] Fig. Figure 9 is an example where the calculation of the control gain is based on the control variable calculation unit 811, which is in Fig. 8 is shown, in the same way as in Fig. 2 is applied. A reference voltage generator 901 is the same as that of the first embodiment, and a control gain calculation unit 903 merely calculates the voltage control gain. The method of calculating the gain is the same as that of the first embodiment.

[0076] The voltage control unit 902 calculates the switching frequency (Fsw) from a voltage difference (ΔV) between the reference voltage (Vref) and the input output voltage (Vo) and from the voltage control gain input by the control gain calculation unit 903.

[0077] Such a configuration makes it possible to reduce the current detection circuitry and the parameters required for control, and to provide a circuit that is easy to adjust. (Third embodiment)

[0078] A third embodiment of the present invention is then described. In the present embodiment, a resonant current supply device with a configuration is described that differs from that of the resonant current supply device 101 in each of the embodiments described above.

[0079] Fig. Figure 10 is a view showing an example of a configuration of a resonant power supply device according to a third embodiment of the present invention. As shown in Fig. As shown in Figure 10, a resonant power supply device 1001 includes a power supply main circuit 1002 and a power supply control circuit 1003. As shown in Fig. As shown in Figure 10, the main power supply circuit 1002 contains a transformer 1007, a secondary-side semiconductor element 1008 and the like.

[0080] The transformer 1007 is configured using a so-called center tap method. In particular, as shown in Fig. As shown in Figure 10, a center tap P115 is provided on a secondary side of transformer 1007. That is, transformer 1007 has three output terminals P113, P114, and P115. The remaining configuration of transformer 1007 is the same as that of transformer 107, which is shown in Figure 10. Fig. 1 is shown.

[0081] The secondary-side semiconductor element 1008 is an element that rectifies a current on the secondary side of the transformer 1007. As shown in Fig. As shown in Figure 10, the secondary-side semiconductor element 1008 contains diodes 1008a and 1008b. For example, a cathode-side end section of diode 1008a is connected to the output terminal P104 of transformer 1007. A cathode-side end section of diode 1008b is connected to the output terminal P113 of transformer 1007. The output terminal P115 of transformer 1007 is connected to an electrode of output-side capacitor 1008 and to output terminal P3 of the main power supply circuit 1002. An anode-side end section of diode 1008a and an anode-side end section of diode 1008b are connected to the other electrode of output-side capacitor 1009 and to the other output terminal P4 of the main power supply circuit 1002.

[0082] If the voltage at output terminal P115 is higher than the voltage at output terminal P113, a current on the secondary side of transformer 1007 is rectified by diode 1008b. Conversely, if the voltage at output terminal P115 is higher than the voltage at output terminal P114, a current on the secondary side of transformer 1007 is rectified by diode 1008a.

[0083] Since the configuration of the power supply control circuit 1003 is the same as that of the second embodiment, a description of it is omitted.

[0084] Even in the resonant power supply unit 1001, which is equipped with the center-tap transformer 1007, as in Fig. As shown in Figure 10, any effect can be obtained as in the embodiments described above. (Fourth embodiment)

[0085] A fourth embodiment of the present invention is then described. In the present embodiment, a resonant power supply device with a configuration that differs from that of each of the embodiments described above is described.

[0086] Fig. Figure 11 is a view showing an example of a configuration of a resonant power supply device according to a fourth embodiment of the present invention. As in Fig. As shown in Figure 11, a resonant power supply device 1101 includes a power supply main circuit 1102 and a power supply control circuit 1103. As shown in Fig. As shown in Figure 11, the main power supply circuit 1102 contains a transformer 1107, a secondary-side semiconductor element 1108 and the like.

[0087] A primary-side semiconductor element 1105 switches a voltage applied to a resonant element 1106 at a predetermined switching frequency. As shown in Fig. As shown in Figure 1, the primary-side semiconductor element 1105 is composed of several switching elements 105a to 105b, each of which is made from a MOSFET such as an NMOS (N-channel MOS).

[0088] For example, as in Fig. As shown in Figure 11, an end section of the switching element 1105a is connected to an input terminal P1 of the main power supply circuit 1102. As shown in Fig. As shown in Figure 11, one end section of switching element 1105b is connected to the other input terminal P2 of the main power supply circuit 1102 and to the resonant capacitor 1106b' of resonant element 1106. The other end section of switching element 1105a and the other end section of switching element 1105b are connected to the resonant inductor 1106a of resonant element 1106. The gates of switching elements 1105a to 1105b are each connected to a switching control signal generator 1113, which is described later.

[0089] The gates of switching elements 1105a to 1105b are switched on and off by the switching control signals Vg1 to Vg2, which are output by the power supply control circuit 1103, based on the corresponding switching control signals Vg1 to Vg42. If the switching element is, for example, constructed from an NMOS, the switching element assumes an on state (is switched on) when a high-level switching control signal is input to the gate. Conversely, if a low-level switching control signal is input to the gate, the switching element assumes an off state (is switched off).

[0090] Since the power supply control circuit 1103 has the same configuration as that of the first embodiment, a description of it is omitted.

[0091] Even in the resonant power supply unit 1101 as in Fig. As shown in Figure 11, any effect can be obtained as in the embodiments described above. (Fifth embodiment)

[0092] A fifth embodiment of the present invention is then described. In this embodiment, a resonant power supply device with a configuration differs from that with the relationship between the control gain and the switching frequency described above is described.

[0093] Fig. Figure 12(a) is a view showing an example of the frequency characteristics of a resonant power supply device, where a vertical axis represents a circuit gain M and a horizontal axis represents a frequency. Here, a circuit gain M is a value defined by the following equation 3, based on an input voltage (Vin), an output voltage (Vo), and the coil windings N1, N2 on the primary and secondary sides of transformer 14. Vo=ML(N2 / N1)L Vin

[0094] According to Fig. 12(a) the switching frequency Fsw decreases when the circuit gain M increases, that is, the circuit gain M and the switching frequency Fsw are in an inversely proportional relationship.

[0095] Therefore, a relationship is established that is in Fig. 12(b) is shown when the relationship between the circuit gain M and the control gain is as in Fig. This is expressed as shown in Figure 4(b). This makes it possible to calculate the control gain using the circuit gain instead of the switching frequency.

[0096] For example, the circuit gain M is referred to as a control gain GainA' when the circuit gain in the configuration is set to Fig.1 the minimum value M2 is, and as a control gain GainB', when the circuit gain in it is the maximum value M1, calculated from (Equation 3) by inputting the input voltage (Vin) of the power supply main circuit 102 into the power supply control circuit 103, which makes it possible to calculate a control gain by (Equation 4), (Equation 4') and (Equation 5) according to the circuit gain M. Gain=α'∗M+β' α=Gain_B'−Gain_A'M1−M2β=(Gain_A'∗M1)−(Gain_B'∗M2)M1−M2 Gain=(Gain_B'−Gain_A')(M1−M2)(M−M2)+Gain_A'

[0097] In this way, the control gain can be calculated even if the switching frequency Fsw itself is not used, using another variable (the circuit gain M in the present embodiment) which is obtained from the switching frequency Fsw. Explanation of reference symbols

[0098] 101 ... Resonant power supply unit; 102 ... Main power supply circuit; 104 ... Input-side capacitor; 108 ... Primary-side semiconductor element; 105a to 105d ... Switching element; 106 ... Resonant element; 107 ... Transformer; 108 ... Secondary-side semiconductor element; 108a to 108d ... Diode; 109 ... Secondary-side capacitor; 103 ... Power supply control circuit; 111 ... Control variable calculation unit; 112 ... Setting unit for an upper and lower switching frequency limit; 113 ... Switching control signal generator; Vg1 to Vg4 ... Switching element control signal; 114 ... Input power supply; and 115 ... Load.

Claims

[1] Resonant power supply device (101) comprising the following: a main power supply circuit (102) comprising a transformer (107), a resonant element (106) connected to a primary side of the transformer (107), and several switching elements (105a, ..., 105d) connected to the resonant element (106); and a power supply control circuit (103) that switches the several switching elements (105a, ..., 105d) in the main power supply circuit (102) at a predetermined switching frequency, wherein the power supply control circuit (103) includes the following: a voltage control unit (202) which outputs a current command value from a reference voltage, an output voltage of the main power supply circuit (102) and a voltage control gain; wherein the voltage control unit (202) performs arithmetic processing such that the current command value decreases when the output voltage is greater than the reference voltage, and increases when the output voltage is less than the reference voltage; a current control unit (203) which calculates the switching frequency from the current command value, an output current flowing on a secondary side of the transformer (107), and a current control gain; wherein the current control unit (203) performs arithmetic processing such that the switching frequency increases when the output current is greater than the current command value, and decreases when the output current is less than the current command value; a gain calculation unit (504) that outputs the voltage control gain and the current control gain; and a control signal generator (113) which, based on the switching frequency output by the current control unit (203), controls several switching elements (105a, ..., 105d), wherein the gain calculation unit (504) outputs the voltage control gain or the current control gain which are proportional to the switching frequency output by the current control unit (203). [2] Resonant current supply device (101) according to claim 1, wherein the gain calculation unit (504) changes a value of the voltage control gain or the current control gain on the basis of the switching frequency immediately before it is output by the current control unit (203). [3] Resonant current supply device (101) according to claim 1, wherein the gain calculation unit (504) outputs the voltage control gain and the current control gain which are proportional to the switching frequency. [4] Resonant power supply device (101) according to claim 1, wherein the power supply control circuit (103) determines whether the switching frequency output by the current control unit (203) is within a predetermined range, and The power supply control circuit (103) corrects the switching frequency to output it to the control signal generator (113) if the switching frequency output by the power control unit (203) is not within the specified range.

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