Bidirectional power supply device

Abstract

A bidirectional power supply device is provided. In the bidirectional power supply device, no hardware is required to select the switching element for action control when switching between the first mode and the second mode. In the first mode, where one end of the power supply circuit (2) is connected to an AC power supply (Pac) and the other end is connected to a DC load (Ldc), the drive signal for the switching element (S2) is generated using an operational current waveform (Itgt1) whose absolute value is larger than the absolute value of the target current waveform (Imag·sinωt). In the second mode, where one end of the power supply circuit (2) is connected to an AC load (Lac) and the other end is connected to a DC power supply (Pdc), the drive signal for the switching element (S2) is generated using an operational current waveform (Itgt2) whose absolute value is smaller than the absolute value of the target current waveform (Imag·sinωt).

Description

Technical Field

[0001] This invention relates to a bidirectional power supply device. Background Technology

[0002] As a bidirectional power supply device, one known device comprises: a totem-pole type PFC circuit having a coil and four switching elements connected in an H-bridge configuration; and a control unit. In a first mode where one end of the PFC circuit is connected to an AC power source and the other end to a DC load, the control unit controls the operation of the switching elements to convert AC power to DC power. In a second mode where one end of the PFC circuit is connected to an AC load and the other end to a DC power source, the control unit controls the operation of the switching elements to convert DC power to AC power. Furthermore, in both the first and second modes, the control unit controls the operation of two switching elements in one arm of the PFC circuit in accordance with the polarity of the AC current, and controls the operation of the switching elements in the other arm to make the current flowing in the coil a target current. As a related technology, Patent Document 1 exists.

[0003] However, as one of the control methods for controlling the operation of switching elements, peak current control has been proposed. This control method controls the on-time of the switching element by comparing a threshold signal waveform based on the target current and a ramp signal with the coil current.

[0004] Here, for example, the switching element of the other arm, which is the controllable switching element, is considered to be the switching element for the period from when the threshold signal waveform coincides with the coil current as the on-time and the period thereafter as the off-time. When the AC polarity is positive, in the first mode, the lower switching element of the other arm needs to be controlled as the controllable switching element to enable the PFC circuit to perform a boost operation; in the second mode, the upper switching element of the other arm needs to be controlled as the controllable switching element to enable the PFC circuit to perform a buck operation.

[0005] In other words, in the bidirectional power supply device described above, when the same threshold signal waveform is used for peak current control in both the first and second modes, the switching element of the controlled object needs to be switched when switching between the first and second modes. This switching requires additional hardware such as selectors, which may increase manufacturing costs.

[0006] Patent Document 1: Japanese Patent Application Publication No. 2019-161830 Summary of the Invention

[0007] One aspect of the present invention relates to an object that provides a bidirectional power supply device that does not require hardware for switching the switching element of the controlled object when switching between a first mode and a second mode.

[0008] A bidirectional power supply device according to one aspect of the present invention includes: a power supply circuit having a coil and switching elements connected by a plurality of arms in an H-bridge configuration; and a control unit that controls the operation of the upper and lower arm switching elements of one arm of the power supply circuit in a first mode where an AC power supply is connected to one end of the power supply circuit and a DC load is connected to the other end of the power supply circuit, or in a second mode where an AC load is connected to one end of the power supply circuit and a DC power supply is connected to the other end of the power supply circuit, in accordance with the polarity of the AC power supply at one end, and controls the operation of the upper and lower arm switching elements of the other arm of the power supply circuit so that the coil current flowing in the coil becomes a target current.

[0009] The control unit, for the other arm drive signal that drives the upper arm switch element and the lower arm switch element of the other arm, in one of the first mode and the second mode, compares the first threshold signal waveform obtained by adding a ramp signal in the direction of zero to the initial operational current value of the switch element at each control cycle using an operational current waveform whose absolute value is larger than the absolute value of the target current waveform, with the coil current, and generates the other arm drive signal that switches between the period from the beginning of the control cycle until the first threshold signal waveform matches the coil current and the period from the first threshold signal waveform matching the coil current until the beginning of the next control cycle.

[0010] Furthermore, in the other of the first and second modes, the control unit compares a second threshold signal waveform obtained by adding a ramp signal in a direction away from zero to the initial operational current value of each control cycle using an operational current waveform whose absolute value is smaller than the absolute value of the target current waveform, with the coil current, and generates another arm drive signal that switches between the period from the beginning of the control cycle until the second threshold signal waveform matches the coil current and the period from the second threshold signal waveform matching the coil current until the beginning of the next control cycle.

[0011] Therefore, there is no need to switch the switching element of the controlled object when switching between the first mode and the second mode, and the switching can be done without the need for hardware for this switching.

[0012] Furthermore, the control unit can be configured such that, in the first mode, a first signal is generated that is designated as an on period from the beginning of the control cycle until the first threshold signal waveform matches the coil current, and as an off period from the beginning of the first threshold signal waveform matching the coil current until the beginning of the next control cycle; and in the second mode, a first signal is generated that is designated as an on period from the beginning of the control cycle until the second threshold signal waveform matches the coil current, and as an off period from the beginning of the second threshold signal waveform matching the coil current until the beginning of the next control cycle. The period from the beginning of the control cycle to the second signal of the disconnection period is set. When the polarity of the AC is positive, the first signal and the second signal are set as the drive signal of a switching element in the other arm, and the inverted signal of the first signal and the second signal is set as the drive signal of another switching element in the other arm. When the polarity of the AC is negative, the first signal and the second signal are set as the drive signal of another switching element in the other arm, and the inverted signal of the first signal and the second signal is set as the drive signal of a switching element in the other arm.

[0013] Alternatively, the control unit may be configured such that, when Imag is set to the amplitude of the target current waveform, ω is set to the angular frequency of the target current waveform, t is set to the current time, Vdc is set to the DC voltage output from the power supply circuit or the DC voltage input to the power supply circuit, VAC is set to the instantaneous value of the AC voltage input to the power supply circuit or the AC voltage output from the power supply circuit, L is set to the inductance value of the coil, SA is set to the amplitude of the ramp signal, and Ts is set to the control period, Itgt1(n), which is the result of the calculation of Equation 1 below, is used as the operating current value used in the first mode, and Itgt2(n), which is the result of the calculation of Equation 2 below, is used as the operating current value used in the second mode.

[0014]

[0015]

[0016] According to the present invention, in a bidirectional power supply device, when switching between a first mode and a second mode, no hardware is required to switch the switching element of the controlled object. Attached Figure Description

[0017] Figure 1 This is a diagram illustrating an example of a bidirectional power supply device according to an embodiment.

[0018] Figure 2 is an example of the coil current, operational current waveform, target current waveform, and first threshold signal waveform in the first mode.

[0019] Figure 3 is an example of the coil current, operational current waveform, target current waveform, and second threshold signal waveform in the second mode.

[0020] Figure 4 is a diagram showing an example of a peak current control circuit and a truth table.

[0021] Explanation of reference numerals in the attached figures

[0022] 1...Bidirectional power supply device; 2...Power supply circuit; 3...Control unit; Svac...Voltage detection unit; Siac...Current detection unit; Svdc...Voltage detection unit; PIC...Peak current control circuit; DRV...Drive circuit; 31...Sine wave generation unit; 32...Multiplication unit; 33...L-value calculation unit; 34...Target current calculation unit. Detailed Implementation

[0023] The following describes the embodiments in detail with reference to the accompanying drawings.

[0024] Figure 1 This is a diagram illustrating an example of a bidirectional power supply device according to an embodiment.

[0025] In the following explanation, "increase" for coil current IL means an absolute increase, and "decrease" means an absolute decrease, i.e., approaching zero.

[0026] Figure 1 The bidirectional power supply device 1 shown includes a power supply circuit 2 and a control unit 3 that controls the operation of the power supply circuit 2. It has a first mode where an AC power source Pac is connected to one end of the power supply circuit 2 and a DC load Ldc is connected to the other end, and a second mode where an AC load Lac is connected to one end of the power supply circuit 2 and a DC power source Pdc is connected to the other end. For example, the bidirectional power supply device 1 is installed in vehicles such as electric vehicles and industrial vehicles. Furthermore, the AC power source Pac is configured as the system power source, the DC load Ldc is configured as a household appliance powered by a secondary battery such as a lithium-ion battery or DC power, the DC power source Pdc is configured as a secondary battery such as a lithium-ion battery, and the AC load Lac is configured as a household appliance powered by AC power such as a personal computer. When the DC load Ldc is configured as a secondary battery, the first mode is for charging, and the second mode is for power supply. Furthermore, the control unit 3 has a function to switch between the first and second modes based on instructions from the user, and can identify which mode is currently in use.

[0027] <Example of the structure of power supply circuit 2 (1)>

[0028] Power supply circuit 2 is a totem-pole type PFC (Power Factor Correction) circuit, and includes four switching elements SW1 to SW4 connected in a bridge configuration with coil CL and H, as well as capacitor C. The switching elements SW1 to SW4 are, for example, MOSFETs (Metal Oxide Semiconductor Field Effect Transistors). Furthermore, without distinguishing between the switching elements SW1 to SW4, they are simply referred to as switching elements SW.

[0029] <Example of connection for coil CL, switching elements SW1~SW4, and capacitor C>

[0030] One terminal of coil CL is connected to one terminal of AC power supply Pac or AC load Laac. The connection point between the source terminal of switching element SW3 and the drain terminal of switching element SW4 is connected to the other terminal of AC power supply Pac or AC load Laac. The other terminal of coil CL is connected to the connection point between the source terminal of switching element SW1 and the drain terminal of switching element SW2. The drain terminals of switching elements SW1 and SW3 are interconnected and connected to one terminal of capacitor C and one terminal of DC load Ldc or DC power supply Pdc. The source terminals of switching elements SW2 and SW4 are interconnected and connected to the other terminal of capacitor C and the other terminal of DC load Ldc or DC power supply Pdc.

[0031] <Examples of the operation of switching elements SW1~SW4 in the first mode>

[0032] In the first mode, during the period when the AC power input to the power supply circuit 2 is positive (the period during which current flows from the AC power source Pac through the coil CL to the switching elements SW1 and SW2 (in the first mode, the coil current IL flowing in this direction is set to positive)), the switching element SW3 of one arm of the power supply circuit 2 is off, and the switching element SW4 of the other arm is on. At this time, the switching element SW2 of the other arm of the power supply circuit 2, which is the control target switching element, is on and off, so that the coil current IL flowing at the coil CL becomes the target current. In addition, when the switching element SW2 is on, the switching element SW1 is off, and when the switching element SW2 is off, the switching element SW1 is on. Furthermore, when the switching element SW2 is on, the coil current IL increases, and when the switching element SW1 is on, the coil current IL decreases. That is, in the first mode, during the period when the AC power input to the power supply circuit 2 is positive, when the switching element SW2 is on, the coil current IL "increases", and when the switching element SW2 is off, the coil current IL "decreases".

[0033] Furthermore, in the first mode and during the period when the AC power input to the power supply circuit 2 is negative (during the period when current flows from switching elements SW1 and SW2 through coil CL to the AC power supply Pac), switching element SW3 of one arm of the power supply circuit 2 is turned on, and switching element SW4 of the other arm is turned off. At this time, the switching element SW1 of the other arm of the power supply circuit 2 is turned on and off to make the coil current IL the target current. In addition, when switching element SW1 is turned on, switching element SW2 is turned off, and when switching element SW1 is turned off, switching element SW2 is turned on. Furthermore, when switching element SW1 is turned on, the coil current IL increases, and when switching element SW2 is turned on, the coil current IL decreases. That is, in the first mode and during the period when the AC power input to the power supply circuit 2 is negative, when switching element SW2 is turned on, the coil current IL "decreases", and when switching element SW2 is turned off, the coil current IL "increases".

[0034] In the first mode, by switching on and off the switching elements SW1~SW4, the AC power input from the AC power source Pac to the power circuit 2 is rectified. The rectified power is smoothed by the capacitor C and output as DC power to the DC load Ldc.

[0035] In addition, by setting the target current so that the waveform of the coil current IL becomes a sine wave and the phase difference between the coil current IL and the AC voltage tends to zero, the power factor during the conversion from AC power to DC power is close to 1, thereby improving the power factor of the power supply circuit 2.

[0036] <Examples of the operation of switching elements SW1~SW4 in the second mode>

[0037] In the second mode, during the period when the AC power output from the power supply circuit 2 is positive (during the period when current flows from switching elements SW1 and SW2 through coil CL to the AC load Lac (in the second mode, the coil current IL flowing in this direction is set to positive)), switching element SW3 of one arm of the power supply circuit 2 is off, and switching element SW4 of the other arm is on. At this time, switching element SW2, the switching element of the other arm of the power supply circuit 2 that is the controlled element, is on and off to make the coil current IL the target current. In addition, when switching element SW2 is on, switching element SW1 is off, and when switching element SW2 is off, switching element SW1 is on. Furthermore, when switching element SW1 is on, the coil current IL increases, and when switching element SW2 is on, the coil current IL decreases. That is, in the second mode, during the period when the AC power output from the power supply circuit 2 is positive, when switching element SW2 is on, the current flowing from coil CL to AC load Lac "decreases", and when switching element SW2 is off, the current flowing from coil CL to AC load Lac "increases".

[0038] Furthermore, in the second mode, and during the period when the AC power output from the power supply circuit 2 is negative (during the period when current flows from the AC load Lac through the coil CL to the switching elements SW1 and SW2), the switching element SW3 of one arm of the power supply circuit 2 is turned on, and the switching element SW4 of the other arm is turned off. At this time, the switching element SW1, which is the control element of the other arm of the power supply circuit 2, is turned on and off to make the coil current IL the target current. In addition, when the switching element SW1 is turned on, the switching element SW2 is turned off, and when the switching element SW1 is turned off, the switching element SW2 is turned on. Furthermore, when the switching element SW2 is turned on, the coil current IL increases, and when the switching element SW1 is turned on, the coil current IL decreases. That is, in the second mode, and during the period when the AC power output from the power supply circuit 2 is negative, when the switching element SW2 is turned on, the coil current IL "increases", and when the switching element SW2 is turned off, the coil current IL "decreases".

[0039] In this way, in the second mode, the DC power input from the DC power supply Pdc to the power circuit 2 is converted into AC power and output to the AC load Lac by switching elements SW1~SW4 on and off.

[0040] <Example of the structure of power supply circuit 2 (2)>

[0041] The power supply circuit 2 includes a voltage detection unit Svac, a current detection unit Siac, a voltage detection unit Svdc, a peak current control circuit PIC, and a drive circuit DRV. Alternatively, the peak current control circuit PIC may be incorporated into the control unit 3.

[0042] The voltage detection unit Svac, composed of an AC voltmeter, detects the AC voltage Vac input from the AC power supply Pac to the power circuit 2 in the first mode, or the AC voltage Vac output from the power circuit 2 to the AC load Lac in the second mode, and sends the detected AC voltage Vac to the control unit 3. Furthermore, the AC voltage Vac detected by the voltage detection unit Svac is converted from an analog value to a digital value and input to the control unit 3.

[0043] The current detection unit Siac, composed of an AC ammeter or similar device, detects the coil current IL flowing at the coil CL in the first mode or in the coil CL in the second mode, and sends the detected coil current IL to the control unit 3. Furthermore, the coil current IL detected by the current detection unit Siac is converted from an analog value to a digital value and input to the control unit 3.

[0044] The voltage detection unit Svdc, composed of a DC voltmeter, detects the DC voltage Vdc output from the power supply circuit 2 to the DC load Ldc in the first mode, or the DC voltage Vdc input from the DC power supply Pdc to the power supply circuit 2 in the second mode, and sends the detected DC voltage Vdc to the control unit 3. Furthermore, the DC voltage Vdc detected by the voltage detection unit Svdc is converted from an analog value to a digital value and input to the control unit 3.

[0045] The peak current control circuit PIC is composed of an integrated circuit (IC). Furthermore, in the first mode, the peak current control circuit PIC outputs drive signals S1' to S4' based on a comparison between a threshold signal waveform calculated from the operational current value Itgt1H(n) (or operational current value Itgt1L(n)) sent from the control unit 3 and a predetermined ramp signal, and the coil current IL detected by the current detection unit Siac. In the second mode, the peak current control circuit PIC outputs drive signals S1' to S4' based on a comparison between a threshold signal waveform calculated from the operational current value Itgt2L(n) (or operational current value Itgt2H(n)) sent from the control unit 3 and a predetermined ramp signal, and the coil current IL detected by the current detection unit Siac. The ramp signal is generated at the peak current control circuit PIC by resetting the voltage value generated by supplying a constant current to the capacitor with a predetermined control period Ts; its amplitude is referred to as SA (described later).

[0046] The drive circuit DRV is composed of ICs, etc. It generates drive signals S1~S4 to operate the switching elements SW1~SW4 based on the drive signals S1´~S4´ output from the peak current control circuit PIC, and outputs the drive signals S1~S4 to the gate terminals of the switching elements SW1~SW4.

[0047] <Peak current control in the first mode>

[0048] Figure 2(a) schematically illustrates the target current waveform Imag·sinωt, the operational current waveform Itgt1H, and the operational current waveform Itgt1L in one cycle under the first mode. Furthermore, Figure 2(b) shows the interval indicated by the dashed line b in Figure 2(a), and illustrates the coil current IL, target current waveform Imag·sinωt, operational current value Itgt1H(n), and first threshold signal waveform for each control cycle Ts of the switching element SW2 under the first mode and when the AC power input to the power supply circuit 2 is positive. Furthermore, Figure 2(c) shows the interval indicated by the dashed line c in Figure 2(a), and illustrates the coil current IL, target current waveform Imag·sinωt, operational current value Itgt1L(n), and first threshold signal waveform for each control cycle Ts of the switching element SW1 under the first mode and when the AC power input to the power supply circuit 2 is negative. In addition, in Figures 2(a) to 2(c), the horizontal axis of the two-dimensional coordinate system represents time, and the vertical axis represents current. Furthermore, in Figures 2(a) to 2(c), the solid line represents the coil current IL, the dashed line represents the target current waveform Imag·sinωt, the single-dotted-dashed line represents the operational current values ​​Itgt1H(n) and Itgt1L(n), the double-dotted-dashed line represents the first threshold signal waveform, and SA represents the amplitude of the ramp signal. Furthermore, slope compensation can also be considered for the ramp signal.

[0049] As shown in Figure 2(a) and Figure 2(b), in the first mode and during the period when the AC power input to the power supply circuit 2 is positive, the control unit 3 calculates the initial (t10, t11, t12) values ​​of the operational current waveform Itgt1H, whose absolute value is greater than the absolute value of the target current waveform Imag·sinωt, which is also the operational current value Itgt1H(n) for each control period Ts. Furthermore, in the first mode and when the AC power input to the power supply circuit 2 is positive, the peak current control circuit PIC compares the first threshold signal waveform obtained by adding a ramp signal tending towards zero to the calculated current value Itgt1H(n) calculated by the control unit 3 with the coil current IL. The period from the beginning of the control cycle Ts until the first threshold signal waveform matches the coil current IL is set as the period when the switching element SW2 is turned on (on period), and the period from the beginning of the first threshold signal waveform matching the coil current IL until the beginning of the next control cycle Ts is set as the period when the switching element SW2 is turned off (off period). The signal composed of these periods Ton and Toff is generated as the drive signal S2´ (first signal), and the inverse signal of the drive signal S2´ is generated as the drive signal S1´. In addition, in the first mode and when the AC power input to the power supply circuit 2 is positive, as shown in FIG2(a), the control unit 3 performs calculations by shifting the operational current value Itgt1L(n) to the negative side, so that the comparison between the first threshold signal waveform based on the operational current value Itgt1L(n) and the coil current IL is not performed in the peak current control circuit PIC.

[0050] As shown in Figure 2(a) and Figure 2(c), in the first mode and when the AC power input to the power supply circuit 2 is negative, the control unit 3 calculates the initial (t20, t21, t22) values ​​of the operational current waveform Itgt1L, whose absolute value is greater than the absolute value of the target current waveform Imag·sinωt, which is also the operational current value Itgt1L(n). Furthermore, in the first mode and when the AC power input to the power supply circuit 2 is negative, the peak current control circuit PIC compares the first threshold signal waveform obtained by adding a ramp signal tending towards zero to the calculated current value Itgt1L(n) calculated by the control unit 3 with the coil current IL. The period from the beginning of the control cycle Ts until the first threshold signal waveform matches the coil current IL is set as the period during which the switching element SW1 is turned on (on period), and the period from the beginning of the first threshold signal waveform matching the coil current IL until the beginning of the next control cycle Ts is set as the period during which the switching element SW1 is turned off (off period). The signal composed of these periods Ton and Toff is generated as the drive signal S1´ (first signal), and the inverted signal of the drive signal S1´ is generated as the drive signal S2´. Furthermore, in the first mode, and when the AC power input to the power supply circuit 2 is negative, as shown in FIG2(a), the control unit 3 performs calculations by shifting the operational current value Itgt1H(n) to the positive side, thereby preventing the comparison between the first threshold signal waveform based on the operational current value Itgt1H(n) and the coil current IL in the peak current control circuit PIC. Additionally, the drive signals S1' and S2' correspond to another arm drive signal of the present invention.

[0051] That is, in the first mode and when the AC power input to the power supply circuit 2 is positive, during the period of drive signal S2' (Ton), the switching element SW2 is turned on, thereby increasing the coil current IL; during the period of drive signal S2' (Toff), the switching element SW2 is turned off, thereby decreasing the coil current IL. Furthermore, in the first mode and when the AC power input to the power supply circuit 2 is negative, during the period of drive signal S1' (Ton), the switching element SW1 is turned on (and the switching element SW2 is turned off), thereby increasing the coil current IL; during the period of drive signal S1' (Toff), the switching element SW1 is turned off (and the switching element SW2 is turned on), thereby decreasing the coil current IL.

[0052] <Peak current control in the second mode>

[0053] Figure 3(a) schematically illustrates the target current waveform Imag·sinωt, the operational current waveform Itgt2H, and the operational current waveform Itgt2L in one cycle under the second mode. Furthermore, Figure 3(b) shows an example of the coil current IL, target current waveform Imag·sinωt, operational current value Itgt2L(n), and second threshold signal waveform for each control cycle Ts of the switching element SW2 under the second mode and when the AC power output from the power supply circuit 2 is positive. Furthermore, Figure 3(c) shows an example of the coil current IL, target current waveform Imag·sinωt, operational current value Itgt2H(n), and second threshold signal waveform for each control cycle Ts of the switching element SW1 under the second mode and when the AC power output from the power supply circuit 2 is negative. In addition, in Figures 3(a) to 3(c), the horizontal axis of the two-dimensional coordinate system represents time, and the vertical axis represents current. Furthermore, in Figures 3(a) to 3(c), the solid line represents the coil current IL, the dashed line represents the target current waveform Imag·sinωt, the single-dotted-dashed line represents the operational current waveforms Itgt2H and Itgt2L, the double-dotted-dashed line represents the second threshold signal waveform, and SA represents the amplitude of the ramp signal.

[0054] As shown in Figures 3(a) and 3(b), in the second mode and when the AC power output from the power supply circuit 2 is positive, the control unit 3 calculates the initial (t30, t31, t32) values ​​of the operational current waveform Itgt2L, whose absolute value is smaller than the absolute value of the target current waveform Imag·sinωt, i.e., the operational current value Itgt2L(n) of each control period Ts. Furthermore, in the second mode and when the AC power output from the power supply circuit 2 is positive, the peak current control circuit PIC compares the second threshold signal waveform obtained by adding a ramp signal in the direction away from zero to the operational current value Itgt2L(n) with the coil current IL. The period from the beginning of the control cycle Ts until the second threshold signal waveform matches the coil current IL is set as the period during which the switching element SW2 is turned on (on period). The period from the beginning of the second threshold signal waveform matching the coil current IL until the beginning of the next control cycle Ts is set as the period during which the switching element SW2 is turned off (off period). The signal composed of these periods Ton and Toff is generated as the drive signal S2´ (second signal), and the inverse signal of the drive signal S2´ is generated as the drive signal S1´. In addition, in the second mode and when the AC power output from the power supply circuit 2 is positive, as shown in FIG3(a), the control unit 3 performs calculations by shifting the operational current value Itgt2H(n) to the positive side, thereby not comparing the second threshold signal waveform based on the operational current value Itgt2H(n) with the coil current IL in the peak current control circuit PIC.

[0055] As shown in Figures 3(a) and 3(c), in the second mode and when the AC power input to the power supply circuit 2 is negative, the control unit 3 calculates the initial (t40, t41, t42) values ​​of the operational current waveform Itgt2H, whose absolute value is smaller than the absolute value of the target current waveform Imag·sinωt, which is also the operational current value Itgt2H(n). Furthermore, in the second mode and when the AC power input to the power supply circuit 2 is negative, the peak current control circuit PIC compares the second threshold signal waveform obtained by adding a ramp signal in the direction away from zero to the operational current value Itgt2H(n) with the coil current IL. The period Ton from the beginning of the control cycle until the second threshold signal waveform matches the coil current IL is set as the period during which the switching element SW1 is turned on (the switching element SW2 is turned off) (on period). The period Toff from the beginning of the second threshold signal waveform matching the coil current IL until the beginning of the next control cycle Ts is set as the period during which the switching element SW1 is turned off (the switching element SW2 is turned on) (off period). The signal composed of these periods Ton and Toff is generated as the drive signal S1´ (second signal), and the inverted signal of the drive signal S1´ is generated as the drive signal S2´. Furthermore, in the second mode, and when the AC power output from the power supply circuit 2 is negative, as shown in FIG3(a), the control unit 3 performs calculations by shifting the operational current value Itgt2L(n) towards the negative side, thereby preventing the comparison between the second threshold signal waveform based on the operational current value Itgt2L(n) and the coil current IL in the peak current control circuit PIC. Additionally, the drive signals S1' and S2' correspond to another arm drive signal of the present invention.

[0056] That is, in the second mode, and when the AC power output from the power supply circuit 2 is positive, during the period of drive signal S2' (Ton), the switching element SW2 is turned on, thereby "decreasing" the coil current IL; during the period of drive signal S2' (Toff), the switching element SW2 is turned off, thereby "increasing" the coil current IL. Furthermore, in the second mode, and when the AC power output from the power supply circuit 2 is negative, during the period of drive signal S1' (Ton), the switching element SW1 is turned on (and the switching element SW2 is turned off), thereby "decreasing" the coil current IL; during the period of drive signal S1' (Toff), the switching element SW1 is turned off (and the switching element SW2 is turned on), thereby "increasing" the coil current IL.

[0057] <Regarding the role and effects based on the implementation method>

[0058] Thus, in the first mode and when the AC power input to the power supply circuit 2 is positive, the first threshold signal waveform obtained based on the calculated current value Itgt1H(n) is compared with the coil current IL, and the driving signal S2´ during this period Ton and Toff (the other arm driving signal) is determined. Therefore, in the first mode and when the AC power input to the power supply circuit 2 is positive, the coil current IL can be "increased" when the switching element SW2 is turned on, and the coil current IL can be "decreased" when the switching element SW2 is turned off.

[0059] Furthermore, in the first mode, and when the AC power input to the power supply circuit 2 is negative, the first threshold signal waveform obtained based on the calculated current value Itgt1L(n) is compared with the coil current IL to determine the periods Ton and Toff (another arm drive signal) of the drive signal S1´. Thus, in the first mode, and when the AC power input to the power supply circuit 2 is negative, the coil current IL can be "decreased" when the switching element SW2 is turned on, and the coil current IL can be "increased" when the switching element SW2 is turned off.

[0060] In the first mode, the first threshold signal waveform obtained by adding a ramp signal tending towards zero to the initial operational current value (Itgt1H(n) or Itgt1L(n)) of the operational current waveform (Itgt1H or Itgt1L) whose absolute value is greater than the absolute value of the target current waveform Imag·sinωt is compared with the coil current IL to generate another arm drive signal.

[0061] Furthermore, in the second mode, and when the AC power output from the power supply circuit 2 is positive, the second threshold signal waveform obtained based on the calculated current value Itgt2L(n) is compared with the coil current IL to determine the periods Ton and Toff (another arm drive signal) of the drive signal S2´. Thus, in the second mode, and when the AC power output from the power supply circuit 2 is positive, the coil current IL can be "decreased" when the switching element SW2 is turned on, and the coil current IL can be "increased" when the switching element SW2 is turned off.

[0062] Furthermore, in the second mode, and when the AC power output from the power supply circuit 2 is negative, the threshold signal waveform obtained based on the operational current value Itgt2H(n), rather than the operational current value Itgt2L(n), is compared with the coil current IL to determine the periods Ton and Toff (another arm drive signal) of the drive signal S1´. Thus, in the second mode, and when the AC power output from the power supply circuit 2 is negative, the coil current IL can be "increased" when the switching element SW2 is turned on, and "decreased" when the switching element SW2 is turned off.

[0063] In the second mode, the second threshold signal waveform, obtained by adding a ramp signal away from zero to the initial operational current value (Itgt2H(n) or Itgt2L(n)) of the operational current waveform (Itgt2H or Itgt2L) whose absolute value is smaller than the absolute value of the target current waveform Imag·sinωt, is compared with the coil current IL to generate another arm drive signal.

[0064] Thus, in the bidirectional power supply device 1 of this embodiment, in both the first and second modes, the generation of the threshold signal waveform compared with the coil current IL is performed by switching between an operational current waveform whose absolute value is greater than the absolute value of the target current waveform Imag·sinωt and an operational current waveform whose absolute value is smaller than the absolute value of the target current waveform Imag·sinωt. Therefore, the switching element of the control object used to follow the target current is the same in both the first and second modes. Consequently, it is not necessary to switch the switching element of the control object when switching between the first and second modes, eliminating the need for hardware to select the switching element of the control object.

[0065] Assuming that in both the first and second modes, the threshold signal waveform for comparison with the coil current IL is fixed to either an operational current waveform whose absolute value is greater than the absolute value of the target current waveform Imag·sinωt, or an operational current waveform whose absolute value is less than the absolute value of the target current waveform Imag·sinωt, then in both the first and second modes, the switching element that is the object of control needs to be switched between switching element SW1 and switching element SW2. Therefore, hardware is needed to select the switching element of the object of control.

[0066] Alternatively, when switching between a positive and a negative period, i.e., when the polarity of the AC signal changes, it is necessary to switch the operational current value used in generating the threshold signal waveform. Therefore, all switching elements are forcibly disconnected during the specified period.

[0067] <Structural Example of Control Unit 3>

[0068] Figure 1 The control unit 3 shown includes a sine wave generation unit 31, a multiplication unit 32, an L-value calculation unit 33, and a target current calculation unit 34. Furthermore, the control unit 3 may be composed of, for example, a CPU (Central Processing Unit), a multi-core CPU, or a programmable device (FPGA (Field Programmable Gate Array), PLD (Programmable Logic Device), etc.).

[0069] The sine wave generation unit 31 generates a sine wave sinωt based on the angular frequency ω of the AC voltage Vac. Furthermore, t is set to the current time, and the angular frequency ω is set to the frequency of the AC voltage Vac × 2π.

[0070] The multiplication unit 32 multiplies the amplitude value Imag of the target current waveform with the sine wave sinωt and outputs the target current waveform Imag·sinωt (ideal sine wave) as the result of the multiplication. Alternatively, the amplitude value Imag of the target current waveform can be obtained based on the DC voltage Vdc.

[0071] The L-value calculation unit 33 calculates the inductance value L of the coil CL using the coil current IL.

[0072] Based on the AC voltage Vac, coil current IL, DC voltage Vdc, amplitude SA of the ramp signal, and target current waveform Imag·sinωt, the target current calculation unit 34 calculates the calculated current values ​​Itgt1H(n) and Itgt1L(n) in the first mode, and calculates the calculated current values ​​Itgt2L(n) and Itgt2H(n) in the second mode.

[0073] <Examples of operations for calculating the current values ​​Itgt1H(n) and Itgt1L(n)>

[0074] For example, the target current calculation unit 34 uses the instantaneous value VAC of the AC voltage Vac, the target current waveform Imag·sinωt, and the inductance value L. It is assumed that the average value of the coil current IL is consistent with the target current waveform Imag·sinωt, that is, it is assumed that the average value of the changing coil current IL formed during the on-time Ton of the control period Ts is consistent with the target current waveform Imag·sinωt when half of the on-time Ton has passed from the initial moment of the on-time Ton. Furthermore, the amount of change in the changing coil current IL formed during the on-time Ton can be represented by the instantaneous value VAC, the inductance value L, and the on-time Ton. Furthermore, the coil current IL at the end of the on-time Ton is consistent with the threshold signal waveform; therefore, the coil current IL at the end of the on-time Ton can be represented using the calculated current value Itgt1H(n) (or Itgt1L(n)), the amplitude SA of the ramp signal, the on-time Ton, and the control period Ts. Furthermore, the on-time Ton can be represented by the ratio of the instantaneous value VAC to the DC voltage Vdc. Using the above conditions, the result of Equation 1 below is used as the calculated current value Itgt1H(n) or the calculated current value Itgt1L(n). Furthermore, when the AC power input to the power supply circuit 2 is positive, the calculated current value Itgt1H(n) is obtained by making the target current waveform Imag·sinωt and the instantaneous value VAC positive; when the AC power input to the power supply circuit 2 is negative, the calculated current value Itgt1L(n) is obtained by making the target current waveform Imag·sinωt and the instantaneous value VAC negative. In addition, the amplitude SA and the control period Ts are pre-stored in the target current calculation unit 34. Alternatively, if the change in the inductance value L does not affect the calculation of the calculated current values ​​Itgt1H(n) and Itgt1L(n), the inductance value L can be pre-stored as a constant in the target current calculation unit 34. In this case, the L value calculation unit 33 can be omitted.

[0075]

[0076] <Examples of operations for calculating current values ​​Itgt2L(n) and Itgt2H(n)>

[0077] For example, the target current calculation unit 34 uses the instantaneous value VAC of the AC voltage Vac, the target current waveform Imag·sinωt, and the inductance value L. Using the same conditions as the calculation examples for the calculated current values ​​Itgt1H(n) and Itgt1L(n), the calculation result of the following equation 2 is obtained as the calculated current value Itgt2L(n) or the calculated current value Itgt2H(n). Furthermore, when the AC power output from the power supply circuit 2 is positive, the calculated current value Itgt2L(n) is obtained by making the target current waveform Imag·sinωt and the instantaneous value VAC negative. When the AC power input to the power supply circuit 2 is negative, the calculated current value Itgt2H(n) is obtained by making the target current waveform Imag·sinωt and the instantaneous value VAC positive.

[0078]

[0079] <Example of deriving the operational current value Itgt1H(n)>

[0080] Let t be the initial moment of the control period Ts (the initial moment of the on-time Ton), and let i(t) be the current value of the coil current IL at this time. In addition, let i(Ton) be the current value of the coil current IL at the end of the on-time Ton (refer to Figure 2(b)). If it is assumed that the average value of the target current waveform Imag·sinω is consistent with the average value of the coil current IL, then Equations 3 and 4 below hold.

[0081] (i(Ton)+i(t)) / 2=Imag·sinω(t+Ton / 2)...Equation 3

[0082] i(Ton) = i(t) + (VAC × Ton) / L……Equation 4

[0083] If we substitute Equation 4 into Equation 3 and rearrange the equations, we get Equation 5.

[0084] i(Ton) = Imag·sinω(t + Ton / 2) + (VAC × Ton) / 2L……Equation 5

[0085] Furthermore, i(Ton) is given by Equation 6 based on the relationship between the operational current value Itgt1H(n) and the amplitude SA.

[0086] i(Ton)=Itgt1H(n)-SA·Ton / Ts...Equation 6

[0087] If we substitute Equation 6 into Equation 5 and rearrange the equation, the operational current value Itgt1H(n) becomes Equation 7.

[0088] Itgt1H(n)=Imag·sinω(t+Ton / 2)+((VAC×Ton) / 2L)+SA·Ton / Ts...Equation 7

[0089] Here, if the period Ton is determined by the boost ratio of the instantaneous value VAC to the DC voltage Vdc, then the following equation 8 can be obtained. If the following equation 8 is solved for the period Ton, then the following equation 9 is obtained.

[0090] Ton / Ts = (1 - VAC / Vdc) ... Equation 8

[0091] Ton = (1 - VAC / Vdc) · Ts ... Equation 9

[0092] Then, if we substitute Equation 9 into Equation 7 and ignore (Ton / 2) as a small value, we get Equation 1.

[0093] Furthermore, the operational current value Itgt2(n) can be derived using the same method as the operational current value Itgt1(n). Additionally, as described above, depending on whether it is a positive or negative period, the operational current value on the side without comparison with the coil current IL (Itgt1L(n) for the positive period in the first mode, Itgt1H(n) for the negative period in the first mode, Itgt2H(n) for the positive period in the second mode, and Itgt2L(n) for the negative period in the second mode) can be obtained by using the value calculated from Equation 1 or Equation 2, or by shifting a predetermined value from the target current waveform Imag·sinωt, etc., without comparison with the coil current IL.

[0094] <Example of Peak Current Control Circuit PIC Structure>

[0095] Figure 4(a) is a diagram showing an example of a peak current control circuit PIC. Figure 4(b) is a diagram showing an example of a truth table corresponding to the logic operation of the peak current control circuit PIC shown in Figure 4(a).

[0096] The drive signal generation unit shown in Figure 4(a) includes a subtractor SUB, an adder ADD, comparators COM1 and COM2, and an OR gate circuit OR.

[0097] In the first mode, the subtractor SUB subtracts the ramp signal from the operational current value Itgt1H(n) and outputs the first threshold signal waveform as the result to the negative input terminal of the comparator COM1. In the second mode, the subtractor SUB subtracts the ramp signal from the operational current value Itgt2H(n) and outputs the second threshold signal waveform as the result to the negative input terminal of the comparator COM1.

[0098] In the first mode, the adder ADD adds the ramp signal to the operation current value Itgt1L(n) and outputs the first threshold signal waveform as the result to the positive input terminal of the comparator COM2. In the second mode, the adder ADD adds the ramp signal to the operation current value Itgt2L(n) and outputs the second threshold signal waveform as the result to the positive input terminal of the comparator COM2.

[0099] When the coil current IL at the positive input terminal is less than the first or second threshold signal waveform at the negative input terminal, the comparator COM1 outputs a low-level signal (L) to one input terminal of the OR gate circuit. When the coil current IL is greater than the first or second threshold signal waveform, the comparator COM1 outputs a high-level signal (H) to one input terminal of the OR gate circuit.

[0100] When the coil current IL at the negative input terminal is less than the first or second threshold signal waveform at the positive input terminal, the comparator COM2 outputs a high-level signal (H) to the other input terminal of the OR gate circuit. When the coil current IL is greater than the first or second threshold signal waveform, the comparator COM2 outputs a low-level signal (L) to the other input terminal of the OR gate circuit.

[0101] An OR gate outputs a high-level signal (H) when at least one of the signals input to one input terminal and the signal input to the other input terminal is high, and outputs a low-level signal (L) when both input signals to the input terminals are low.

[0102] Furthermore, during the positive period, the signal output from the OR gate is output to the DRV drive circuit as drive signal S1', and the inverted signal of drive signal S1' is output to the DRV drive circuit as drive signal S2'. During the negative period, the signal output from the OR gate is output to the DRV drive circuit as drive signal S2', and the inverted signal of drive signal S2' is output to the DRV drive circuit as drive signal S1'. Additionally, circuits such as flip-flops are provided on the output sides of comparators COM1 and COM2 to maintain the signal level. If the output signals of comparators COM1 and COM2 switch from low to high, they remain at a high level until the next control cycle begins.

[0103] For example, in the first mode and when the AC power input to the power supply circuit 2 is positive, during the period Ton, the output signal of comparator COM1 becomes low and the output signal of comparator COM2 becomes low. Therefore, the drive signal S1', which is the output signal of the OR gate circuit, becomes low. During the period Toff, the output signal of comparator COM1 becomes high and the output signal of comparator COM2 becomes low. Therefore, the drive signal S1', which is the output signal of the OR gate circuit, becomes high. Therefore, in the first mode and when the AC power input to the power supply circuit 2 is positive, during the period Ton, the switching element SW2 can be turned on to "increase" the coil current IL, and during the period Toff, the switching element SW2 can be turned off to "decrease" the coil current IL.

[0104] Furthermore, in the first mode, and when the AC power input to the power supply circuit 2 is negative, during period Ton, the output signal of comparator COM1 becomes low, the output signal of comparator COM2 becomes low, and therefore, the drive signal S2', which is the output signal of the OR gate circuit, becomes low. During period Toff, the output signal of comparator COM1 becomes low, the output signal of comparator COM2 becomes high, and therefore, the drive signal S2', which is the output signal of the OR gate circuit, becomes high. Therefore, in the first mode, and when the AC power input to the power supply circuit 2 is negative, during period Ton, the switching element SW2 can be turned off, thereby increasing the coil current IL; during period Toff, the switching element SW2 can be turned on, thereby decreasing the coil current IL.

[0105] Furthermore, in the second mode, and when the AC power output from the power supply circuit 2 is positive, during the period Ton, the output signal of comparator COM1 becomes low, the output signal of comparator COM2 becomes low, and therefore, the drive signal S1', which is the output signal of the OR gate circuit, becomes low. During the period Toff, the output signal of comparator COM1 becomes low, the output signal of comparator COM2 becomes high, and therefore, the drive signal S1', which is the output signal of the OR gate circuit, becomes high. Therefore, in the second mode, and when the AC power output from the power supply circuit 2 is positive, during the period Ton, the switching element SW2 can be turned on to "decrease" the coil current IL, and during the period Toff, the switching element SW2 can be turned off to "increase" the coil current IL.

[0106] Furthermore, in the second mode, and when the AC power output from the power supply circuit 2 is negative, during period Ton, the output signal of comparator COM1 becomes low, and the output signal of comparator COM2 becomes low. Therefore, the drive signal S2', which is the output signal of the OR gate circuit, becomes low. During period Toff, the output signal of comparator COM1 becomes high, and the output signal of comparator COM2 becomes low. Therefore, the drive signal S2', which is the output signal of the OR gate circuit, becomes high. Therefore, in the second mode, and when the AC power output from the power supply circuit 2 is negative, during period Ton, the switching element SW2 can be turned off, thereby "reducing" the coil current IL. During period Toff, the switching element SW2 can be turned on, thereby "increasing" the coil current IL.

[0107] In other words, the output signal of the OR gate circuit OR in Figure 4(b) is the same in both the first and second modes. Therefore, switching of the control object's switching element is not required in either mode. Thus, in both modes, the control object's switching element SW2 can be turned on and off during positive periods, and SW1 can be turned on and off during negative periods. Therefore, hardware for switching the control object's switching element is not required when switching between the first and second modes.

[0108] Furthermore, by simply changing the operational current value input to the peak current control circuit PIC, AC power can be converted to DC power in the first mode and DC power can be converted to AC power in the second mode without changing the logic operation of the peak current control circuit PIC. Therefore, the increased manufacturing cost associated with changing the logic operation of the peak current control circuit PIC can be avoided.

[0109] Furthermore, the present invention is not limited to the above embodiments, and various improvements and modifications can be made without departing from the spirit of the present invention.

[0110] <Variation Example 1>

[0111] In the above embodiments, the switching element that is controlled, which makes the coil current IL follow the target current, is configured such that, in both the first and second modes, the operation of the switching element SW2 is controlled during the positive period of the other arm of the power supply circuit 2, and the operation of the switching element SW1 is controlled during the negative period. However, this structure can also be substituted, where the switching element controlled controls the operation of the switching element SW1 during the positive period of the other arm, and controls the operation of the switching element SW2 during the negative period. In this configuration, in both the first and second modes, the calculated current values ​​Itgt1H(n), Itgt1L(n), Itgt2H(n), and Itgt2L(n) are calculated in such a way that the coil current IL becomes the target current.

[0112] Even with this configuration, it is possible to switch the switching element of the controlled object without switching between the first and second modes, and there is no need for hardware to select the switching element of the controlled object.

[0113] <Variation Example 2>

[0114] In the above embodiment, the configuration is such that, during the positive period, a signal is generated that marks the period from the beginning of the control cycle Ts until the coil current IL coincides with the threshold signal waveform as the on-time of switching element SW2 (one switching element of the other arm), and the period from the beginning of the coil current IL coinciding with the threshold signal waveform until the beginning of the next control cycle Ts as the off-time of switching element SW2, serving as the drive signal for switching element SW2. Furthermore, the configuration is such that, during the negative period, a signal is generated that marks the period from the beginning of the control cycle Ts until the coil current IL coincides with the threshold signal waveform as the on-time of switching element SW1 (another switching element of the other arm), and the period from the beginning of the coil current IL coinciding with the threshold signal waveform until the beginning of the next control cycle Ts as the off-time of switching element SW1, serving as the drive signal for switching element SW1. However, this configuration is not limited to this structure. Alternatively, during a positive period, a signal is generated that serves as the drive signal for switch element SW2, representing the period from the beginning of control cycle Ts until the coil current IL matches the threshold signal waveform as the off period and the period from the beginning of the coil current IL matching the threshold signal waveform until the beginning of the next control cycle Ts as the on period. During a negative period, a signal is generated that serves as the off period for switch element SW1, representing the period from the beginning of control cycle Ts until the coil current IL matches the threshold signal waveform and the period from the beginning of the next control cycle Ts as the on period. In this configuration, in both the first and second modes, the calculated current values ​​Itgt1H(n), Itgt1L(n), Itgt2H(n), and Itgt2L(n) are calculated in a way that makes the coil current IL the target current.

[0115] Even with this configuration, the switching element SW of the controlled object can be controlled to operate by making the coil current IL the target current in both the first and second modes. Therefore, it is not necessary to switch the switching element of the controlled object when switching between the first and second modes, and there is no need for hardware to select the switching element of the controlled object.

[0116] <Variation Example 3>

[0117] In the above embodiments, for generating the threshold signal waveform compared with the coil current IL, in the first mode, an operational current waveform with an absolute value larger than the absolute value of the target current waveform Imag·sinωt is used; in the second mode, an operational current waveform with an absolute value smaller than the absolute value of the target current waveform Imag·sinωt is used. However, this structure is not limited to this. Alternatively, in the first mode, an operational current waveform with an absolute value smaller than the absolute value of the target current waveform Imag·sinωt is used; and in the second mode, an operational current waveform with an absolute value larger than the absolute value of the target current waveform Imag·sinωt is used.

[0118] Even with this configuration, the switching element SW of the controlled object can be controlled in both the first and second modes by making the coil current IL the target current. Therefore, it is not necessary to switch the switching element of the controlled object when switching between the first and second modes, and there is no need for hardware to select the switching element of the controlled object.

[0119] <Variation Example 4>

[0120] In the above embodiments, an arm may be constructed using switching elements SW1 and SW2, which serve as switching elements for another arm. However, multiple arms may also be used as another arm and operate alternately. In this case, switching element SW1 can be used for the multiple upper arm switching elements of the multiple arms, and switching element SW2 can be used for the multiple lower arm switching elements. Alternatively, multiple arms may be used for a single arm.

[0121] <Variation Example 5>

[0122] In the above embodiment, the DC load Ldc and the DC power supply Pdc are directly connected to the other end of the power supply circuit 2, which is the DC side. Alternatively, the DC load Ldc and the DC power supply Pdc can be connected to the other end of the power supply circuit 2, which is the DC side, via a DC-DC converter.

Claims

1. A bidirectional power supply device, characterized in that, have: A power supply circuit having a coil and a switching element connected by a multi-arm H-bridge; and The control unit, in either a first mode where an AC power source is connected to one end of the power circuit and a DC load is connected to the other end, or in a second mode where an AC load is connected to one end of the power circuit and a DC power source is connected to the other end, controls the operation of the upper and lower arm switching elements of one arm of the power circuit in accordance with the polarity of the AC power source at one end, and controls the operation of the upper and lower arm switching elements of the other arm of the power circuit to make the coil current flowing in the coil a target current. The control unit provides drive signals for the other arm that drive the upper arm switching elements and lower arm switching elements of the other arm. In either the first mode or the second mode, a first threshold signal waveform, obtained by adding a ramp signal tending towards zero to the initial operational current value of the operational current waveform at each control cycle of the switching element using an operational current waveform whose absolute value is larger than the absolute value of the target current waveform, is compared with the coil current. This generates another arm drive signal that switches between the period from the beginning of the control cycle until the first threshold signal waveform matches the coil current, and the period from the period when the first threshold signal waveform matches the coil current until the beginning of the next control cycle. In the other of the first and second modes, a second threshold signal waveform, obtained by adding a ramp signal in a direction away from zero to the operational current waveform with an operational current waveform whose absolute value is smaller than that of the target current waveform at the beginning of each control cycle, is compared with the coil current to generate another arm drive signal that switches between the period from the beginning of the control cycle until the second threshold signal waveform matches the coil current and the period from the second threshold signal waveform matching the coil current until the beginning of the next control cycle.

2. The bidirectional power supply device according to claim 1, characterized in that, For the control unit... In the first mode, a first signal is generated that defines the period from the beginning of the control cycle until the first threshold signal waveform matches the coil current as the on-time period, and the period from the beginning of the first threshold signal waveform matching the coil current until the beginning of the next control cycle as the off-time period. In the second mode, a second signal is generated, which is defined as the on-period from the beginning of the control cycle until the second threshold signal waveform matches the coil current, and as the off-period from the beginning of the next control cycle until the second threshold signal waveform matches the coil current. When the polarity of the AC signal is positive, the first signal and the second signal are set as the drive signal for a switching element in the other arm, and the inverted signal of the first signal and the second signal is set as the drive signal for another switching element in the other arm. When the polarity of the AC is negative, the first signal and the second signal are set as the drive signal for another switching element in the other arm, and the inverted signal of the first signal and the second signal is set as the drive signal for a switching element in the other arm.

3. The bidirectional power supply device according to claim 1, characterized in that, When the control unit sets Imag to the amplitude of the target current waveform, ω to the angular frequency of the target current waveform, t to the current time, Vdc to the DC voltage output from or input to the power supply circuit, VAC to the instantaneous value of the AC voltage input to or output from the power supply circuit, L to the inductance of the coil, SA to the amplitude of the ramp signal, and Ts to the control period, it uses Itgt1(n), which is the result of the calculation of Equation 1 below, as the operating current value used in the first mode, and Itgt2(n), which is the result of the calculation of Equation 2 below, as the operating current value used in the second mode. 。

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