DC converter and vehicle-mounted DC conversion equipment

Abstract

The embodiment of the present application provides a DC converter and a vehicle-mounted DC conversion device, the DC converter includes a controller, a first power conversion unit, an isolation transformer unit and a voltage regulation circuit; the voltage regulation circuit includes a resonant circuit and a second power conversion unit; when the DC converter is in a reverse working mode, the controller controls the first power conversion unit to convert the input first DC voltage into a first AC voltage; the isolation transformer unit is used to convert the first AC voltage into a second AC voltage, the effective value of the second AC voltage is greater than the effective value of the first AC voltage; the effective value of the first AC voltage is greater than zero; when the effective value of the second AC voltage is less than the first target DC voltage, the controller controls the energy storage element in the resonant circuit to be in an energy storage mode in the first time period; the controller controls the energy storage element in the resonant circuit to be in an energy release mode in the second time period. The embodiment of the present application can achieve high-gain reverse DC conversion.

Description

Technical Field

[0001] The present application relates to the technical field of electronic circuits, and in particular to a direct current converter and a vehicle-mounted direct current conversion device. Background Art

[0002] In recent years, with the rapid development of the new energy vehicle industry, there are more and more functional requirements for on-board direct current (DC) converters that provide energy for low-voltage devices. They must not only realize forward DC conversion: that is, convert high-voltage DC into low-voltage DC, but also have other auxiliary functions: for example, convert low-voltage DC into high-voltage DC by discharging and precharging the high-voltage bus. However, the battery voltage on the low-voltage side is usually low, while the voltage on the high-voltage side is very high, and the current DC converter cannot achieve high-gain reverse DC conversion. Summary of the invention

[0003] The embodiments of the present application provide a DC converter and a vehicle-mounted DC conversion device, which can achieve high-gain reverse DC conversion.

[0004] A first aspect of an embodiment of the present application provides a DC converter, including a controller, a first power conversion unit, an isolation transformer unit, and a voltage regulation circuit; the voltage regulation circuit includes a resonant circuit and a second power conversion unit;

[0005] When the DC converter is in a reverse working mode, the controller controls the first power conversion unit to convert an input first DC voltage into a first AC voltage;

[0006] The isolation transformer unit is used to convert the first AC voltage into a second AC voltage, the effective value of the second AC voltage is greater than the effective value of the first AC voltage; the effective value of the first AC voltage is greater than zero;

[0007] When the effective value of the second AC voltage is less than the first target DC voltage, the controller controls the energy storage element in the resonant circuit to be in an energy storage mode in a first time period; in the energy storage mode, the second power conversion unit controls the second AC voltage to store energy to the energy storage element in the resonant circuit; the controller controls the energy storage element in the resonant circuit to be in an energy release mode in a second time period; in the energy release mode, the second power conversion unit controls the energy storage element to supply power to the load; in the first time period, the energy storage in the energy storage element is on an upward trend; in the second time period, the energy storage in the energy storage element is on a downward trend.

[0008] Optionally, the controller controls the first power conversion unit to convert the input first DC voltage into a first AC voltage, including:

[0009] The controller sends a first control signal to the first power conversion unit, where the first control signal is used to control the first power conversion unit to convert an input first DC voltage into a first AC voltage;

[0010] When the effective value of the second AC voltage is greater than the first target DC voltage, the controller reduces the duty cycle of the first control signal.

[0011] Optionally, the second power conversion unit includes: a first switch tube, a second switch tube, a third switch tube and a fourth switch tube; the resonant circuit includes a resonant inductor, an excitation inductor and a resonant capacitor; the isolation transformer unit includes a first winding and a second winding, and the number of turns of the first winding is greater than the number of turns of the second winding;

[0012] The first end of the first switch tube is connected to the first end of the third switch tube and the first end of the load, the second end of the first switch tube is connected to the first end of the second switch tube and the first end of the resonant inductor, the second end of the resonant inductor is connected to the first end of the excitation inductor and the first end of the first winding, the second end of the excitation inductor is connected to the second end of the first winding and the first end of the resonant capacitor, the second end of the resonant capacitor is connected to the first end of the fourth switch tube and the second end of the third switch tube, and the second end of the fourth switch tube is connected to the second end of the second switch tube and the second end of the load.

[0013] Optionally, the DC converter further includes a first capacitor, and the first power conversion unit includes: a fifth switch tube, a sixth switch tube, a seventh switch tube and an eighth switch tube;

[0014] The first end of the fifth switch tube is connected to the first end of the seventh switch tube and the positive electrode of the first capacitor, the second end of the seventh switch tube is connected to the first end of the second winding and the first end of the eighth switch tube, the second end of the second winding is connected to the second end of the fifth switch tube and the first end of the sixth switch tube, and the second end of the sixth switch tube is connected to the second end of the eighth switch tube and the negative electrode of the first capacitor.

[0015] Optionally, the controller controls the energy storage element in the resonant circuit to be in an energy storage mode during the first time period, including:

[0016] In the first time period, if the voltage between the first end and the second end of the first winding is positive, the controller controls the second switch tube to be turned on and the first switch tube to be turned off, and the resonant inductor, the second switch tube, the fourth switch tube, the resonant capacitor and the excitation inductor form a first resonant circuit, so that the resonant inductor stores energy;

[0017] During the first time period, if the voltage between the first end and the second end of the first winding is a negative value, the controller controls the first switch tube to be turned on and the second switch tube to be turned off, and the resonant inductor, the excitation inductor, the resonant capacitor, the third switch tube, and the first switch tube form a second resonant circuit to enable the resonant inductor to store energy.

[0018] Optionally, the controller controls the energy storage element in the resonant circuit to be in an energy release mode during the second time period, including:

[0019] In the second time period, when the voltage between the first end and the second end of the first winding is positive, the controller controls the first switch tube to be turned on and the second switch tube to be turned off, and the resonant inductor supplies power to the load through the first switch tube;

[0020] During the second time period, when the voltage between the first end and the second end of the first winding is negative, the controller controls the second switch tube to be turned on and the first switch tube to be turned off, and the resonant inductor supplies power to the load through the excitation inductor, the resonant capacitor, and the third switch tube.

[0021] Optionally, the first control signal includes a first wave transmission control signal and a second wave transmission control signal;

[0022] The first wave control signal is used to control the conduction or shutoff of the fifth switch tube and the eighth switch tube; the second wave control signal is used to control the conduction or shutoff of the sixth switch tube and the seventh switch tube;

[0023] When the first ripple control signal controls the fifth switch tube and the eighth switch tube to be turned on, and the second ripple control signal controls the sixth switch tube and the seventh switch tube to be turned off, the voltage between the first end and the second end of the second winding is a negative value;

[0024] When the first waving control signal controls the fifth switch tube and the eighth switch tube to be turned off, and the second waving control signal controls the sixth switch tube and the seventh switch tube to be turned on, the voltage between the first end and the second end of the second winding is a positive value; the frequency of the first waving control signal is equal to the frequency of the second waving control signal, and the duty cycle of the first waving control signal is equal to the duty cycle of the second waving control signal.

[0025] Optionally, the controller controls the energy storage element in the resonant circuit to be in an energy storage mode or an energy release mode through a second control signal; the second control signal includes a first energy storage charging control signal and a second energy storage charging control signal; the frequency of the first energy storage charging control signal is equal to the frequency of the second energy storage charging control signal, and the duty cycle of the first energy storage charging control signal is equal to the duty cycle of the second energy storage charging control signal; the frequency of the first wave transmission control signal is equal to the frequency of the first energy storage charging control signal, and the duty cycle of the first wave transmission control signal is equal to the duty cycle of the first energy storage charging control signal;

[0026] The first energy storage charging control signal is used to control the on or off of the first switch tube; the second energy storage charging control signal is used to control the on or off of the second switch tube.

[0027] Optionally, a phase shift angle between the first energy storage charging control signal and the first wave transmission control signal is greater than 0 and less than 90 degrees;

[0028] The phase shift angle between the second energy storage charging control signal and the second wave transmission control signal is greater than 0 and less than 90 degrees.

[0029] Optionally, the frequency of the first oscillation control signal is greater than or equal to the resonant frequency of the resonant circuit.

[0030] Optionally, the DC converter further includes a second capacitor, and the first power conversion unit includes: a ninth switch tube and a tenth switch tube;

[0031] The first end of the ninth switch tube is connected to the first end of the second winding, the first end of the tenth switch tube is connected to the second end of the second winding, the first end of the second capacitor is connected to the middle tap of the second winding, and the second end of the ninth switch tube is connected to the second end of the tenth switch tube and the second end of the second capacitor.

[0032] Optionally, when the DC converter is in a forward working mode, the controller controls the voltage regulating circuit to convert the input second DC voltage into a third AC voltage;

[0033] The isolation transformer unit is used to convert the third AC voltage into a fourth AC voltage, wherein the effective value of the fourth AC voltage is smaller than the effective value of the third AC voltage;

[0034] The controller controls the first power conversion unit to convert the fourth AC voltage into a second target DC voltage.

[0035] A second aspect of an embodiment of the present application provides a vehicle-mounted DC conversion device, comprising the DC converter described in the first aspect above.

[0036] The DC converter of the embodiment of the present application includes a controller, a first power conversion unit, an isolation transformer unit and a voltage regulation circuit; the voltage regulation circuit includes a resonant circuit and a second power conversion unit; when the DC converter is in a reverse working mode, the controller controls the first power conversion unit to convert the input first DC voltage into a first AC voltage; the isolation transformer unit is used to convert the first AC voltage into a second AC voltage, the effective value of the second AC voltage is greater than the effective value of the first AC voltage; the effective value of the first AC voltage is greater than zero; when the effective value of the second AC voltage is less than the first target DC voltage, the controller controls the energy storage element in the resonant circuit to be in an energy storage mode in the first time period; in the energy storage mode, the second power conversion unit controls the second AC voltage to store energy to the energy storage element in the resonant circuit; the controller controls the energy storage element in the resonant circuit to be in an energy release mode in the second time period; in the energy release mode, the second power conversion unit controls the energy storage element to supply power to the load; in the first time period, the energy storage in the energy storage element is in an upward trend; in the second time period, the energy storage in the energy storage element is in a downward trend. During the energy storage process, the effective values ​​of the first AC voltage and the second AC voltage are greater than zero.

[0037] In the embodiment of the present application, when the DC converter is in the reverse working mode, the input first DC voltage can be converted into a first AC voltage through the first power conversion unit, and the first AC voltage can be converted into a second AC voltage with a higher effective value through the isolation transformer unit to achieve AC voltage boosting. Then, when the effective value of the second AC voltage is less than the first target DC voltage, that is, when the rectified DC voltage of the second AC voltage is still lower than the first target DC voltage, the controller allows the energy storage element in the resonant circuit to continue to store energy in the first time period, and allows the energy storage element to supply power to the load in the second time period. Since the energy storage in the energy storage element is on an upward trend in the first time period and the energy storage in the energy storage element is on a downward trend in the second time period, the energy storage of the energy storage element can be maximized, so that the voltage after the energy storage element supplies power to the load can reach the first target DC voltage, thereby achieving high-gain reverse DC conversion. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0039] Figure 1 is a structural schematic diagram of a DC converter provided in an embodiment of the present application;

[0040] Figure 2 is a structural schematic diagram of another DC converter provided in an embodiment of the present application;

[0041] Figure 3 is a waveform diagram of a control signal provided in an embodiment of the present application;

[0042] Figure 4 is a structural schematic diagram of another DC converter provided in an embodiment of the present application;

[0043] Figure 5 It is a structural schematic diagram of a vehicle-mounted DC conversion device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0044] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of this application.

[0045] The terms "first", "second", etc. in the specification and claims of this application and the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, products or devices.

[0046] Reference to "embodiments" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described in this application may be combined with other embodiments.

[0047] See also Figure 1 , Figure 1 Schematic diagram of a DC converter provided in an embodiment of the present application. Figure 1As shown, the DC converter 100 includes a controller 10, a first power conversion unit 20, an isolation transformer unit 30 and a voltage regulating circuit 40; the voltage regulating circuit 40 includes a resonant circuit 41 and a second power conversion unit 42;

[0048] When the DC converter 100 is in a reverse working mode, the controller 10 controls the first power conversion unit 20 to convert the input first DC voltage into a first AC voltage;

[0049] The isolation transformer unit 30 is used to convert the first AC voltage into a second AC voltage, the effective value of the second AC voltage is greater than the effective value of the first AC voltage; the effective value of the first AC voltage is greater than zero;

[0050] When the effective value of the second AC voltage is less than the first target DC voltage, the controller 10 controls the energy storage element in the resonant circuit 41 to be in an energy storage mode in a first time period; in the energy storage mode, the second power conversion unit 42 controls the second AC voltage to store energy to the energy storage element in the resonant circuit 41; the controller 10 controls the energy storage element in the resonant circuit 41 to be in an energy release mode in a second time period; in the energy release mode, the second power conversion unit 42 controls the energy storage element to supply power to the load Z1; in the first time period, the energy storage in the energy storage element is on an upward trend; in the second time period, the energy storage in the energy storage element is on a downward trend.

[0051] The load Z1 may be a capacitor, an inductor, a resistor, or a combination of at least two of the capacitors, inductors, and resistors, which is not limited in the embodiment of the present application.

[0052] The energy storage element in the resonant circuit 41 may be an energy storage inductor, such as a resonant inductor in the resonant capacitor 41 .

[0053] In the embodiment of the present application, the DC converter 100 can be in a forward working mode or a reverse working mode.

[0054] When the DC converter 100 is in the reverse working mode, Figure 1 The low voltage DC voltage V_LV on the right is converted to Figure 1 The high voltage DC voltage V_HV on the left can realize the conversion from low voltage DC to high voltage DC.

[0055] When the DC converter 100 is in the forward working mode, Figure 1 The high voltage DC voltage V_HV on the left is converted to Figure 1 The low voltage DC voltage V_LV on the right can realize the conversion from high voltage DC to low voltage DC.

[0056] When the DC converter 100 is in the reverse working mode, the controller 10 controls the first power conversion unit 20 to convert the input first DC voltage (low voltage DC voltage V_LV) into a first AC voltage, the isolation transformer unit 30 converts the first AC voltage into a second AC voltage (at this time, the isolation transformer unit 30 works in the isolation boost mode), and the controller 10 controls the voltage regulation circuit 40 to convert the second AC voltage into a first target DC voltage. The first target DC voltage is the high voltage side ( Figure 1 ) on the left side of the second AC voltage. If the effective value of the second AC voltage is less than the first target DC voltage, it indicates that the second AC voltage after the isolation transformer unit 30 is boosted is still less than the first target DC voltage after being converted into a DC voltage. At this time, under the control of the controller 10, the controller 10 allows the energy storage element in the resonant circuit 41 to continuously store energy in the first time period, and allows the energy storage element to supply power to the load Z1 in the second time period. Since the energy storage in the energy storage element is in an upward trend in the first time period, and the energy storage in the energy storage element is in a downward trend in the second time period, the voltage after the energy storage element supplies power to the load Z1 can reach the first target DC voltage, thereby achieving high-gain reverse DC conversion.

[0057] When the DC converter 100 is in the forward working mode, the controller 10 controls the voltage regulating circuit to convert the input second DC voltage (high voltage DC voltage V_HV) into a third AC voltage; the isolation transformer unit 30 converts the third AC voltage into a fourth AC voltage (at this time the isolation transformer unit 30 works in the isolated step-down mode), and the controller 10 controls the first power conversion unit 20 to convert the fourth AC voltage into a second target DC voltage.

[0058] Optionally, the controller 10 controls the first power conversion unit 20 to convert the input first DC voltage into a first AC voltage, including:

[0059] The controller 10 sends a first control signal to the first power conversion unit 20, where the first control signal is used to control the first power conversion unit 20 to convert an input first DC voltage into a first AC voltage;

[0060] When the effective value of the second AC voltage is greater than the first target DC voltage, the controller 10 reduces the duty cycle of the first control signal.

[0061] Among them, the first control signal can drive the first power conversion unit 20 to work, so that the first power conversion unit 20 converts the first DC voltage into the first AC voltage. The first control signal can control the amplitude and frequency of the first AC voltage. Specifically, the frequency of the first AC voltage can be adjusted according to the frequency of the first control signal, and the amplitude of the first AC voltage can be adjusted according to the duty cycle of the first control signal. The larger the duty cycle of the first control signal, the larger the amplitude of the first AC voltage. The first control signal can be a pulse width modulation (PWM) signal. For example, the first control signal can be a square wave signal with a duty cycle of D, and D is between 0 and 50%. The DC converter 100 is in the reverse working mode. In order to maximize the DC voltage output by the DC converter 100, the initial duty cycle of the first control signal can be set to 50%.

[0062] The isolation transformer unit 30 can be a transformer, and the transformer can step up or step down the voltage by controlling the turns ratio of the winding to achieve conversion between AC voltages. When the DC converter 100 is in the reverse working mode, the isolation transformer unit 30 can achieve the function of stepping up, that is, it can convert the AC voltage with a low effective value into an AC voltage with a high effective value. When the DC converter 100 is in the forward working mode, the isolation transformer unit 30 can achieve the function of stepping down, that is, it can convert the AC voltage with a high effective value into an AC voltage with a low effective value.

[0063] If the first DC voltage is Vin, the first target DC voltage is Vo, and the turns ratio of the isolation transformer unit 30 is n:1, then Vo=n*Vin*D. Wherein, D is the duty cycle of the first control signal. Since Vin and n are both known in advance, when n*Vin*D>Vo (that is, when the effective value of the second AC voltage is greater than the first target DC voltage), by lowering the value of D, Vo=n*Vin*D.

[0064] The controller 10 can control the duty cycle D of the first control signal so that the DC converter 100 can output the first target DC voltage Vo when working in reverse. n*Vin is the effective value of the second AC voltage.

[0065] In the embodiment of the present application, when the DC converter 100 is in the reverse working mode and the effective value of the second AC voltage is greater than the first target DC voltage, the duty cycle of the first control signal can be reduced to control the effective value of the second AC voltage to be equal to the first target DC voltage. The DC voltage for reverse working can be simply and effectively regulated by lowering the duty cycle of the first control signal.

[0066] See also Figure 2 , Figure 2It is a structural schematic diagram of another DC converter provided in an embodiment of the present application. Figure 2 is Figure 1 It is obtained by further optimization based on . Figure 2 As shown, the second power conversion unit 42 includes: a first switch tube Q1, a second switch tube Q2, a third switch tube Q3 and a fourth switch tube Q4; the resonant circuit 41 includes a resonant inductor Lr, an excitation inductor Lm and a resonant capacitor Cr; the isolation transformer unit 30 includes a first winding W1 and a second winding W2, and the number of turns of the first winding W1 is greater than the number of turns of the second winding W2; wherein, the ratio of the number of turns of the first winding W1 to the number of turns of the second winding W2 is n (the ratio of the number of turns of the first winding W1 to the number of turns of the second winding W2 refers to: the ratio of the number of turns between the first end and the second end of the first winding W1 to the number of turns between the first end and the second end of the second winding W2), and n is greater than 0.

[0067] The first end of the first switch tube Q1 is connected to the first end of the third switch tube Q3 and the first end of the load Z1, the second end of the first switch tube Q1 is connected to the first end of the second switch tube Q2 and the first end of the resonant inductor Lr, the second end of the resonant inductor Lr is connected to the first end of the excitation inductor Lm and the first end of the first winding W1, the second end of the excitation inductor Lm is connected to the second end of the first winding W1 and the first end of the resonant capacitor Cr, the second end of the resonant capacitor Cr is connected to the first end of the fourth switch tube Q4 and the second end of the third switch tube Q3, and the second end of the fourth switch tube Q4 is connected to the second end of the second switch tube Q2 and the second end of the load Z1. When the load Z1 is a capacitor, if the capacitor is a non-polar capacitor, the first end of the load Z1 can be the first end of the capacitor, and the second end of the load Z1 can be the second end of the capacitor; if the capacitor is a polar capacitor, the first end of the load Z1 can be the positive electrode of the capacitor, and the second end of the load Z1 can be the negative electrode of the capacitor.

[0068] Figure 2 The switch tube in the example is an N-type metal-oxide-semiconductor (NMOS) transistor. Figure 2 It can be seen that each switch tube is connected in parallel with a parasitic diode, which is caused by the manufacturing process. Figure 2 A parasitic diode is connected in parallel between the drain (D pole) and the source (S pole) of the NMOS transistor, the anode of the parasitic diode is connected to the source of the NMOS transistor, and the cathode of the parasitic diode is connected to the drain of the NMOS transistor.

[0069] In the embodiment of the present application, the second power conversion unit 42 is in the energy storage mode in the first time period under the control of the controller 10. In the first time period, the controller 10 controls the second switch tube Q2 to be turned on in the first time period, so that the parasitic diodes of the resonant inductor Lr, the second switch tube Q2, and the fourth switch tube Q4, the resonant capacitor Cr, and the excitation inductor Lm form a resonant circuit, and controls the current in the resonant inductor Lr to rise, and the energy storage in the resonant inductor Lr is in an upward trend. The second power conversion unit 42 is in the energy release mode in the second time period under the control of the controller 10. In the second time period, the current in the resonant inductor Lr decreases. At this time, the resonant inductor Lr is used to supply power to the load Z1, so that the energy storage of the resonant inductor Lr can be maximized, so that the voltage after the resonant inductor Lr supplies power to the load Z1 can reach the first target DC voltage, thereby achieving high-gain reverse DC conversion.

[0070] During the energy storage process, the effective values ​​of the first AC voltage and the second AC voltage are greater than zero. During the energy storage process, the voltages at both ends of the first winding W1 and the second winding W2 of the isolation transformer unit will not be equal to zero. When storing energy, the first winding W1 and / or the second winding W2 will not be short-circuited, but the energy storage of the resonant inductor Lr is achieved by controlling the shutdown of the first switch tube Q1 and the second switch tube Q2. If the first winding W1 and / or the second winding W2 are short-circuited, the isolation transformer unit suspends energy transfer, and the energy transfer efficiency is low. In the embodiment of the present application, when the resonant inductor Lr is storing energy, there is no need to short-circuit the first winding W1 and / or the second winding W2. When Lr is storing energy, the isolation transformer unit is still transferring energy, and the energy conversion efficiency is higher.

[0071] Optional, see Figure 2 , Figure 2 The DC converter 100 shown further includes a first capacitor C1, and the first power conversion unit 20 includes: a fifth switch tube Q5, a sixth switch tube Q6, a seventh switch tube Q7 and an eighth switch tube Q8;

[0072] A first end of the fifth switch tube Q5 is connected to a first end of the seventh switch tube Q7 and a positive electrode of the first capacitor C1, a second end of the seventh switch tube Q7 is connected to a first end of the second winding W2 and a first end of the eighth switch tube Q8, a second end of the second winding W2 is connected to a second end of the fifth switch tube Q5 and a first end of the sixth switch tube Q6, and a second end of the sixth switch tube Q6 is connected to a second end of the eighth switch tube Q8 and a negative electrode of the first capacitor C1.

[0073] In the embodiment of the present application, when the controller 10 controls the sixth switch tube Q6 and the seventh switch tube Q7 to be turned on and the fifth switch tube Q5 and the eighth switch tube Q8 to be turned off, the first end of the second winding W2 (such as Figure 2A end) and the second end (such as Figure 2 The voltage V_AB (first AC voltage) between the first end of the first winding W1 (such as Figure 2 The C-terminus) and the second end (such as Figure 2 The voltage V_CD (second AC voltage) between the D terminal and the input terminal is a positive value.

[0074] When the controller 10 controls the fifth switch tube Q5 and the eighth switch tube Q8 to be turned on and the sixth switch tube Q6 and the seventh switch tube Q7 to be turned off, the first end of the second winding W2 (eg Figure 2 A end) and the second end (such as Figure 2 The voltage V_AB (first AC voltage) between the first end of the first winding W1 (such as Figure 2 The C-terminus) and the second end (such as Figure 2 The voltage V_CD (second AC voltage) between the D terminal and the input terminal is a negative value.

[0075] Optionally, the controller 10 controls the energy storage element in the resonant circuit 41 to be in the energy storage mode during the first time period, including:

[0076] In the first time period, if the voltage V_CD (i.e., the second AC voltage) between the first end and the second end of the first winding W1 is positive, the controller 10 controls the second switch tube Q2 to be turned on and the first switch tube Q1 to be turned off, and the resonant inductor Lr, the second switch tube Q2, the fourth switch tube Q4, the resonant capacitor Cr and the excitation inductor Lm form a first resonant circuit, so that the resonant inductor Lr stores energy;

[0077] In the first time period, if the voltage V_CD between the first end and the second end of the first winding W1 is a negative value, the controller 10 controls the first switch tube Q1 to be turned on and the second switch tube Q2 to be turned off, and the resonant inductor Lr, the excitation inductor Lm, the resonant capacitor Cr, the third switch tube Q3, and the first switch tube Q1 form a second resonant circuit to store energy in the resonant inductor Lr.

[0078] Optionally, the controller 10 controls the energy storage element in the resonant circuit 41 to be in an energy release mode during the second time period, including:

[0079] In the second time period, when the voltage between the first end and the second end of the first winding W1 is positive, the controller 10 controls the first switch tube Q1 to be turned on and the second switch tube Q2 to be turned off, and the resonant inductor Lr supplies power to the load Z1 through the first switch tube Q1;

[0080] During the second time period, when the voltage between the first end and the second end of the first winding W1 is negative, the controller 10 controls the second switch tube Q2 to be turned on and the first switch tube Q1 to be turned off, and the resonant inductor Lr supplies power to the load Z1 through the excitation inductor Lm, the resonant capacitor Cr, and the third switch tube Q3.

[0081] Optionally, the first control signal includes a first wave transmission control signal and a second wave transmission control signal;

[0082] The first wave control signal is used to control the on or off of the fifth switch tube Q5 and the eighth switch tube Q8; the second wave control signal is used to control the on or off of the sixth switch tube Q6 and the seventh switch tube Q7;

[0083] When the first ripple control signal controls the fifth switch tube Q5 and the eighth switch tube Q8 to be turned on, and the second ripple control signal controls the sixth switch tube Q6 and the seventh switch tube Q7 to be turned off, the voltage between the first end and the second end of the second winding W2 is a negative value;

[0084] When the first waving control signal controls the fifth switch tube Q5 and the eighth switch tube Q8 to be turned off, and the second waving control signal controls the sixth switch tube Q6 and the seventh switch tube Q7 to be turned on, the voltage between the first end and the second end of the second winding W2 is a positive value; the frequency of the first waving control signal is equal to the frequency of the second waving control signal, and the duty cycle of the first waving control signal is equal to the duty cycle of the second waving control signal.

[0085] When the DC converter 100 is in the reverse working mode, the first control signal is a ripple signal. The controller 10 can control the on and off of the switch tube in the first power conversion unit 20 through the first control signal, thereby converting the first DC voltage into a first AC voltage to realize the ripple function.

[0086] Optionally, the controller 10 controls the energy storage element in the resonant circuit 41 to be in an energy storage mode or an energy release mode through a second control signal; the second control signal includes a first energy storage charging control signal and a second energy storage charging control signal; the frequency of the first energy storage charging control signal is equal to the frequency of the second energy storage charging control signal, and the duty cycle of the first energy storage charging control signal is equal to the duty cycle of the second energy storage charging control signal; the frequency of the first wave transmission control signal is equal to the frequency of the first energy storage charging control signal, and the duty cycle of the first wave transmission control signal is equal to the duty cycle of the first energy storage charging control signal;

[0087] The first energy storage charging control signal is used to control the on or off of the first switch tube Q1; the second energy storage charging control signal is used to control the on or off of the second switch tube Q2.

[0088] Optionally, a phase shift angle between the first energy storage charging control signal and the first wave transmission control signal is greater than 0 and less than 90 degrees;

[0089] The phase shift angle between the second energy storage charging control signal and the second wave transmission control signal is greater than 0 and less than 90 degrees.

[0090] Among them, the phase shift angle between the first energy storage charging control signal and the first wave transmission control signal is greater than 0 and less than 90 degrees, that is, π / 2, and the phase shift angle between the second energy storage charging control signal and the second wave transmission control signal is greater than 0 and less than 90 degrees, that is, π / 2.

[0091] See also Figure 3 , Figure 3 is a waveform diagram of a control signal provided in an embodiment of the present application. Figure 3 As shown, DR_P_H is the first energy storage charging control signal, DR_P_L is the second energy storage charging control signal, V_CD is the voltage between the first end and the second end of the first winding W1, and V_EF is the voltage between the first end of the resonant inductor Lr and the second end of the resonant capacitor Cr (as shown in FIG. Figure 2 DR_S_H is the first transmission control signal, and DR_S_L is the second transmission control signal. DR_P_H is ahead of DR_S_H, and DR_P_L is ahead of DR_S_L. Figure 3 In the example, the lead time is 1 / 4 cycle, which is converted into a phase shift angle of π / 2. Figure 3 The waveform of the control signal is applied in Figure 2 In the circuit, Figure 2 All the switch tubes in the example are NMOS tubes (high level turns on, low level turns off).

[0092] from Figure 3It can be seen that in the t1 time period, V_CD<0, DR_P_H drives Q1 to turn on to store energy for the resonant inductor Lr, and the current on Lr gradually rises to the positive maximum value (reaching the maximum at the junction of t1 and t2); in the t2 time period, V_CD<0, DR_P_L drives Q2 to turn on, and Lr supplies power to the load Z1. At this time, the current I_Lr on Lr gradually decreases, and V_EF rises to the positive maximum value; in the t3 time period, V_CD>0, DR_P_L drives Q2 to turn on to store energy for the inductor Lr, and the current on Lr gradually rises to the negative maximum value (reaching the maximum at the junction of t3 and t4), and V_EF decreases; in the t4 time period, V_CD>0, DR_P_H drives Q1 to turn on, and Lr supplies power to Z1. At this time, the absolute value of the current on Lr gradually decreases, and V_EF decreases to the negative maximum value.

[0093] The input-output gain expression can be found in the following formula:

[0094]

[0095] Wherein, Vo is the first target DC voltage, Vin is the first DC voltage, t_on represents the phase shift time within a resonance cycle, t_off represents the time excluding the phase shift time within a resonance cycle, and n is the ratio of the number of turns of the first winding W1 to the number of turns of the second winding W2. Optionally, the frequency of the first oscillation control signal is greater than or equal to the resonance frequency of the resonance circuit.

[0096] In the embodiment of the present application, when the frequency of the first oscillation control signal is equal to the resonant frequency of the resonant circuit, the more energy stored in the resonant inductor Lr, the higher the input-output gain.

[0097] Optionally, the input-output gain expression can be found in the following formula:

[0098]

[0099] The input-output voltage gain formula is derived as follows:

[0100] Resonant frequency

[0101] The maximum current and voltage on the resonant inductor (Q is the circuit quality factor):

[0102] Umax:=Q·Up

[0103] Imax:=Q·Ir

[0104] Resonant angular frequency: ω:＝ 2 π · f r

[0105] Instantaneous current and voltage on the resonant inductor:

[0106] U(t):=Umax·cos(ω·t)

[0107] I(t):=Imax·sin(ω·t)

[0108] The volt-second product of the inductor during energy storage:

[0109]

[0110] The volt-second product of the inductor during energy release:

[0111] E_off:=(Vo-Up)·t_off

[0112] From the volt-second balance we have:

[0113] E_on:=E_off

[0114] Then we have:

[0115]

[0116] This formula is applicable to fixed frequency phase shift and fixed frequency bandwidth modulation. Fixed frequency means that the frequency of the first energy storage charging control signal, the frequency of the second energy storage charging control signal, the frequency of the first wave control signal and the frequency of the first energy storage charging control signal are fixed. In fixed frequency phase shift, t_on represents the phase shift time; in fixed frequency bandwidth modulation, t_on represents the turn-on time of the power switch tube (Q1 or Q2).

[0117] The embodiment of the present application can utilize the resonant inductor in the resonant circuit to construct a two-way staggered parallel boost converter circuit.

[0118] See also Figure 4 , Figure 4 It is a structural schematic diagram of another DC converter provided in an embodiment of the present application. Figure 4 is Figure 1 It is obtained by further optimization based on . Figure 4 As shown, the DC converter 100 further includes a second capacitor C2, and the first power conversion unit 20 includes: a ninth switch tube Q9 and a tenth switch tube Q10;

[0119] A first end of the ninth switch tube Q9 is connected to a first end of the second winding W2, a first end of the tenth switch tube Q10 is connected to a second end of the second winding W2, a positive electrode of the second capacitor C2 is connected to a middle tap of the second winding W2, and a second end of the ninth switch tube Q9 is connected to a second end of the tenth switch tube Q10 and a negative electrode of the second capacitor C2.

[0120] The number of turns between the middle tap of the second winding W2 and the second end of the second winding W2 is smaller than the number of turns between the first end and the second end of the second winding W2.

[0121] When DR_S_H is at a low level and DR_S_L is at a high level, the first power conversion unit 20 converts the input first DC voltage into a first AC voltage V_OB which is a positive value, and the second AC voltage V_CD is also a positive value; when DR_S_H is at a high level and DR_S_L is at a low level, the first power conversion unit 20 converts the input first DC voltage into a first AC voltage V_AO which is a negative value, and the second AC voltage V_CD is also a negative value.

[0122] The embodiment of the present application provides another structure of the first power conversion unit 20, which can also realize the function of wave generation.

[0123] See also Figure 5 , Figure 5 Schematic diagram of the structure of a vehicle-mounted DC conversion device provided in an embodiment of the present application. Figure 5 As shown, the vehicle-mounted DC conversion device 1000 includes Figure 1 The DC converter shown may also include a first control switch S1, a second control switch S2, a high-voltage DC power supply V_HV and a low-voltage DC power supply V_LV. Only when the first control switch S1 and the second control switch S2 are turned on at the same time can the conversion between the two DC power supplies (V_HV on the left and V_LV on the right) be achieved.

[0124] The embodiment of the present application designs a vehicle-mounted DC conversion device including a DC converter. When the DC converter is in a reverse working mode, the input first DC voltage can be converted into a first AC voltage through a first power conversion unit, and the first AC voltage can be converted into a second AC voltage with a higher effective value through an isolation transformer unit to achieve AC voltage boosting. Then, when the effective value of the second AC voltage is less than the first target DC voltage, that is, when the rectified DC voltage of the second AC voltage is still lower than the first target DC voltage, the controller allows the energy storage element in the resonant circuit to continue to store energy in the first time period, and allows the energy storage element to supply power to the load in the second time period. Since the energy storage in the energy storage element is on an upward trend in the first time period and the energy storage in the energy storage element is on a downward trend in the second time period, the energy storage of the energy storage element can be maximized, so that the voltage after the energy storage element supplies power to the load can reach the first target DC voltage, thereby achieving high-gain reverse DC conversion.

[0125] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0126] In the several embodiments provided in the present application, it should be understood that the disclosed DC converter and vehicle-mounted DC conversion device can be implemented in other ways. For example, the DC converter embodiments described above are only schematic, and for example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed.

Claims

1. A DC converter, characterized in that: It includes a controller, a first power conversion unit, an isolation transformer unit and a voltage regulation circuit; the voltage regulation circuit includes a resonant circuit and a second power conversion unit; When the DC converter is in a reverse working mode, the controller controls the first power conversion unit to convert an input first DC voltage into a first AC voltage; The isolation transformer unit is used to convert the first AC voltage into a second AC voltage, the effective value of the second AC voltage is greater than the effective value of the first AC voltage; the effective value of the first AC voltage is greater than zero; When the effective value of the second AC voltage is less than the first target DC voltage, the controller controls the energy storage element in the resonant circuit to be in an energy storage mode in a first time period; in the energy storage mode, the second power conversion unit controls the second AC voltage to store energy to the energy storage element in the resonant circuit; the controller controls the energy storage element in the resonant circuit to be in an energy release mode in a second time period; in the energy release mode, the second power conversion unit controls the energy storage element to supply power to the load; in the first time period, the energy storage in the energy storage element is on an upward trend; in the second time period, the energy storage in the energy storage element is on a downward trend.

2. The DC converter according to claim 1, characterized in that: The controller controls the first power conversion unit to convert an input first DC voltage into a first AC voltage, including: The controller sends a first control signal to the first power conversion unit, where the first control signal is used to control the first power conversion unit to convert an input first DC voltage into a first AC voltage; When the effective value of the second AC voltage is greater than the first target DC voltage, the controller reduces the duty cycle of the first control signal.

3. The DC converter according to claim 2, characterized in that: The second power conversion unit includes: a first switch tube, a second switch tube, a third switch tube and a fourth switch tube; the resonant circuit includes a resonant inductor, an excitation inductor and a resonant capacitor; the isolation transformer unit includes a first winding and a second winding, and the number of turns of the first winding is greater than the number of turns of the second winding; The first end of the first switch tube is connected to the first end of the third switch tube and the first end of the load, the second end of the first switch tube is connected to the first end of the second switch tube and the first end of the resonant inductor, the second end of the resonant inductor is connected to the first end of the excitation inductor and the first end of the first winding, the second end of the excitation inductor is connected to the second end of the first winding and the first end of the resonant capacitor, the second end of the resonant capacitor is connected to the first end of the fourth switch tube and the second end of the third switch tube, and the second end of the fourth switch tube is connected to the second end of the second switch tube and the second end of the load.

4. The DC converter according to claim 3, characterized in that: The DC converter further includes a first capacitor, and the first power conversion unit includes: a fifth switch tube, a sixth switch tube, a seventh switch tube and an eighth switch tube; The first end of the fifth switch tube is connected to the first end of the seventh switch tube and the positive electrode of the first capacitor, the second end of the seventh switch tube is connected to the first end of the second winding and the first end of the eighth switch tube, the second end of the second winding is connected to the second end of the fifth switch tube and the first end of the sixth switch tube, and the second end of the sixth switch tube is connected to the second end of the eighth switch tube and the negative electrode of the first capacitor.

5. The DC converter according to claim 4, characterized in that: The controller controls the energy storage element in the resonant circuit to be in an energy storage mode during a first time period, including: In the first time period, if the voltage between the first end and the second end of the first winding is positive, the controller controls the second switch tube to be turned on and the first switch tube to be turned off, and the resonant inductor, the second switch tube, the fourth switch tube, the resonant capacitor and the excitation inductor form a first resonant circuit, so that the resonant inductor stores energy; During the first time period, if the voltage between the first end and the second end of the first winding is a negative value, the controller controls the first switch tube to be turned on and the second switch tube to be turned off, and the resonant inductor, the excitation inductor, the resonant capacitor, the third switch tube, and the first switch tube form a second resonant circuit to enable the resonant inductor to store energy.

6. The DC converter according to claim 5, characterized in that: The controller controls the energy storage element in the resonant circuit to be in an energy release mode during the second time period, including: In the second time period, when the voltage between the first end and the second end of the first winding is positive, the controller controls the first switch tube to be turned on and the second switch tube to be turned off, and the resonant inductor supplies power to the load through the first switch tube; During the second time period, when the voltage between the first end and the second end of the first winding is negative, the controller controls the second switch tube to be turned on and the first switch tube to be turned off, and the resonant inductor supplies power to the load through the excitation inductor, the resonant capacitor, and the third switch tube.

7. The DC converter according to claim 6, characterized in that: The first control signal includes a first wave transmission control signal and a second wave transmission control signal; The first wave control signal is used to control the conduction or shutoff of the fifth switch tube and the eighth switch tube; the second wave control signal is used to control the conduction or shutoff of the sixth switch tube and the seventh switch tube; When the first ripple control signal controls the fifth switch tube and the eighth switch tube to be turned on, and the second ripple control signal controls the sixth switch tube and the seventh switch tube to be turned off, the voltage between the first end and the second end of the second winding is a negative value; When the first waving control signal controls the fifth switch tube and the eighth switch tube to be turned off, and the second waving control signal controls the sixth switch tube and the seventh switch tube to be turned on, the voltage between the first end and the second end of the second winding is a positive value; the frequency of the first waving control signal is equal to the frequency of the second waving control signal, and the duty cycle of the first waving control signal is equal to the duty cycle of the second waving control signal.

8. The DC converter according to claim 7, characterized in that: The controller controls the energy storage element in the resonant circuit to be in an energy storage mode or an energy release mode through a second control signal; the second control signal includes a first energy storage charging control signal and a second energy storage charging control signal; the frequency of the first energy storage charging control signal is equal to the frequency of the second energy storage charging control signal, and the duty cycle of the first energy storage charging control signal is equal to the duty cycle of the second energy storage charging control signal; the frequency of the first wave control signal is equal to the frequency of the first energy storage charging control signal, and the duty cycle of the first wave control signal is equal to the duty cycle of the first energy storage charging control signal; The first energy storage charging control signal is used to control the on or off of the first switch tube; the second energy storage charging control signal is used to control the on or off of the second switch tube.

9. The DC converter according to claim 8, characterized in that: The phase shift angle between the first energy storage charging control signal and the first wave generation control signal is greater than 0, A phase shift angle between the second energy storage charging control signal and the second wave generation control signal is greater than 0.

10. The DC converter according to claim 8 or 9, characterized in that: The frequency of the first oscillation control signal is greater than or equal to the resonant frequency of the resonant circuit.

11. The DC converter according to claim 3, characterized in that: The DC converter further includes a second capacitor, and the first power conversion unit includes: a ninth switch tube and a tenth switch tube; The first end of the ninth switch tube is connected to the first end of the second winding, the first end of the tenth switch tube is connected to the second end of the second winding, the first end of the second capacitor is connected to the middle tap of the second winding, and the second end of the ninth switch tube is connected to the second end of the tenth switch tube and the second end of the second capacitor.

12. A vehicle-mounted DC conversion device, characterized in that: It comprises a DC converter as claimed in any one of claims 1 to 11.

Images