Isolation power supply and vehicle

Abstract

The utility model discloses an isolation power supply and a vehicle, and relates to the technical field of power supplies, the isolation power supply comprises a buck-boost circuit and an LLC resonance circuit; the buck-boost circuit comprises a first control unit; the first control unit is used for providing a pulse width modulation signal of a first frequency for the control end of each power switch tube in the buck-boost circuit; the voltage input end of the buck-boost circuit is connected to the first voltage end; the voltage output end of the buck-boost circuit is connected to the voltage input end of the LLC resonant circuit; the LLC resonant circuit comprises a second control unit; and the second control unit is used for providing a switch control signal of a second frequency for each control switch tube in the LLC resonant circuit. According to the circuit, a stable low-voltage power supply can be provided through the pulse width modulation signal of the first frequency, and at the moment, the second frequency is increased, so that high-density power transmission can be realized, and high-power-density transmission under low voltage is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power supply, in particular to an isolated power supply and a vehicle. BACKGROUND

[0002] With the development of current new energy vehicle technology, new energy drive inverters have become core components in the vehicle power system.

[0003] The isolated power supply in the inverter is an important electrical architecture component. The common drive isolated power supply is a flyback transformer type or a push-pull isolated transformer type. In recent years, LLC topology has been practically applied in the vehicle system, which overcomes the problem of insufficient power density of high-power low-voltage power supply. However, the range of input voltage of the traditional LLC topology is limited, and the existing isolated power supply cannot meet the high-power density transmission under low voltage. CONTENT OF THE INVENTION

[0004] The present application provides an isolated power supply and a vehicle, which can realize high-power density transmission under low voltage,

[0005] In a first aspect, an isolated power supply is provided, which includes a buck-boost circuit and an LLC resonant circuit.

[0006] The first control unit is configured to provide a pulse width modulation signal of a first frequency to the control end of each power switch tube in the buck-boost circuit. The voltage input end of the buck-boost circuit is connected to a first voltage end. The voltage output end of the buck-boost circuit is connected to the voltage input end of the LLC resonant circuit.

[0007] The second control unit is configured to provide a switching control signal of a second frequency to each control switch tube in the LLC resonant circuit. The voltage output end of the LLC resonant circuit is configured to output a target voltage.

[0008] In a possible implementation, each power switch tube in the buck-boost circuit includes a first power switch tube, a second power switch tube, a third power switch tube, and a fourth power switch tube.

[0009] The voltage input end of the buck-boost circuit is connected to a first node through the first power switch tube. The first node is grounded through the second power switch tube. The first node is connected to a second node through a first inductor.

[0010] The second node is connected to the voltage output end of the buck-boost circuit through the third power switch tube. The second node is also grounded through the fourth power switch tube.

[0011] The voltage output end of the voltage-lifting and voltage-lowering circuit is connected to ground through an output capacitor.

[0012] In a possible implementation, the voltage-lifting and voltage-lowering circuit comprises a first current sampler; the first current sampler is configured to sample the current flowing from the first voltage end to the first power switch tube.

[0013] In a possible implementation, the LLC resonant circuit is a half-bridge LLC resonant circuit.

[0014] In a possible implementation, each control switch tube in the LLC resonant circuit comprises a first control switch tube and a second control switch tube.

[0015] The voltage input end of the LLC resonant circuit is connected to a third node through the first control switch tube; the third node is also connected to ground through the second control switch tube; the third node is connected to the primary input end of a transformer; the primary output end of the transformer is connected to ground through a resonant capacitor; the secondary side of the transformer is configured to output the target voltage.

[0016] In a possible implementation, the switch control signal is a high-frequency pulse wave with an output duty cycle of 50%.

[0017] In a possible implementation, the LLC resonant circuit further comprises a second current sampler; the second current sampler is configured to sample the current flowing from the voltage input end of the LLC resonant circuit to the first control switch tube.

[0018] In a possible implementation, the input end of the secondary side of the transformer is connected to a first voltage end, an isolation ground end and a second voltage end through a rectifier circuit respectively.

[0019] The first voltage end is configured to output a positive target voltage; and the second voltage end is configured to output a negative target voltage.

[0020] In a possible implementation, the first end of the secondary side of the transformer is connected to a fourth node through a first diode; the fourth node is connected to the second end of the secondary side of the transformer through a first capacitor; the second end of the secondary side of the transformer is connected to a fifth node through a second capacitor; the fifth node is connected to the first end of the secondary side of the transformer through a second diode.

[0021] The fourth node is also connected to the fifth node through a third capacitor; the fourth node is connected to a sixth node through a fourth capacitor; the fourth node is also connected to the sixth node through a first resistor; the sixth node is connected to the fifth node through a fifth capacitor; and the sixth node is also connected to the fifth node through a voltage stabilizing diode.

[0022] The fourth node is connected to the first voltage end through a first magnetic bead; the sixth node is connected to the isolated ground end through a second magnetic bead; and the fifth node is connected to the second voltage end through a third magnetic bead.

[0023] In a second aspect, a vehicle is provided, and the vehicle is provided with the isolated power supply.

[0024] The technical scheme provided in the application can have the following beneficial effects.

[0025] The isolated power supply provided in the application comprises a boost-buck circuit and an LLC resonant circuit, and the boost-buck circuit comprises a first control unit; the first control unit is configured to provide a pulse width modulation signal of a first frequency to a control end of each power switch tube in the boost-buck circuit; at this time, the boost-buck circuit can boost or buck the voltage of the first voltage end to a specified voltage value according to the selected first frequency, and transmit the voltage to a voltage input end of the LLC resonant circuit; and the LLC resonant circuit comprises a second control unit, which can provide a switching control signal of a second frequency to each control switch tube; at this time, the LLC resonant circuit can perform energy transmission of a specified power density according to the selected second frequency. The above circuit can provide a stable low-voltage power supply through the pulse width modulation signal of the first frequency, and at this time, the second frequency is increased, that is, high-density power transmission can be achieved, so that high-power-density transmission under low voltage is achieved. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical scheme in the specific embodiments or prior art of the application, the drawings needed in the description of the specific embodiments or prior art will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0027] Figure 1 FIG. 1 is a structural schematic diagram of an isolated power supply according to an example embodiment.

[0028] Figure 2 FIG. 2 shows a system block diagram of an isolated power supply according to an embodiment of the application.

[0029] Figure 3 FIG. 3 shows a power supply control logic diagram according to an embodiment of the application. DETAILED DESCRIPTION

[0030] The technical solutions of the present application will be clearly and completely described below with reference to the drawings. Obviously, the described embodiments are some of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0031] In the description of the embodiments of the present application, the term "corresponding" can represent a direct or indirect corresponding relationship between the two, can also represent an associated relationship between the two, or can indicate a relationship such as indicated, configured, etc.

[0032] Figure 1 is a structural schematic diagram of an isolated power supply according to an exemplary embodiment. As Figure 1 shown, the isolated power supply includes a boost-buck circuit and an LLC resonant circuit;

[0033] The boost-buck circuit includes a first control unit A1; the first control unit A1 is used to provide a pulse width modulation signal of a first frequency to the control end of each power switch tube in the boost-buck circuit; the voltage input end of the boost-buck circuit is connected to a first voltage end; the voltage output end of the boost-buck circuit is connected to the voltage input end of the LLC resonant circuit;

[0034] The LLC resonant circuit includes a second control unit A2; the second control unit A2 is used to provide a switching control signal of a second frequency to each control switch tube in the LLC resonant circuit; the voltage output end of the LLC resonant circuit is used to output a target voltage.

[0035] The boost-buck circuit (BUCKBOOST circuit) in the embodiments of the present application includes a plurality of power switch tubes, and by setting the pulse width modulation signals received by the plurality of power switch tubes, the output voltage value of the boost-buck circuit can be controlled. In the embodiments of the present application, if low-voltage high-power density energy output is required, the BUCKBOOST circuit can be provided with a pulse width modulation signal of a lower frequency (i.e. the first frequency), so that the BUCKBOOST circuit outputs a lower supply voltage value. For example, in automotive electronics, the low-voltage application scenario is usually 3-40V, and the output voltage value of the voltage output VCC of the BUCKBOOST circuit can be set to 24V.

[0036] The LLC resonant circuit realizes efficient energy transmission through a resonant network, wherein the control switch tube in the LLC resonant circuit generates a high-frequency square wave signal, thereby driving the resonant network to work, and the resonant network converts the square wave signal into an alternating voltage close to a sine wave, which is rectified into a stable direct current output after isolation by a transformer.

[0037] Therefore, in the case ofFigure 1 In the isolated power supply shown, the buck-boost circuit is controlled by a first frequency (which can be set to a low frequency, such as a frequency range of 100kHz-1MHz) to provide a low-voltage and stable power reference. Then, the LLC resonant circuit is controlled by a second frequency (which can be set to a high frequency, such as a frequency range of 20MHz-30MHz) to achieve high-efficiency energy transfer through high-frequency resonance, and finally outputs positive and negative isolated voltages to supply the load.

[0038] Please refer to Figure 2 The diagram illustrates a block diagram of an isolated power supply system according to an embodiment of this application. Figure 2 As shown, in one possible implementation of this application embodiment, the buck-boost circuit is a four-switch Buck-Boost topology. Specifically, each power switch in the buck-boost circuit includes a first power switch Q1, a second power switch Q2, a third power switch Q3, and a fourth power switch Q4;

[0039] The voltage input terminal of the buck-boost circuit is connected to the first node through the first power switch Q1; the first node is grounded through the second power switch Q2; and the first node is connected to the second node through the first inductor Lb.

[0040] The second node is connected to the voltage output terminal of the buck-boost circuit through the third power switch Q3; the second node is also grounded through the fourth power switch Q4;

[0041] The voltage output terminal VCC of the buck-boost circuit is grounded through the output capacitor Cb.

[0042] The control of the four-switch Buck-Boost topology is mainly achieved through PWM (Pulse Width Modulation) signals. The PWM duty cycle is adjusted according to the relationship between the input and output voltages to ensure that the output voltage meets the requirements. The four-switch Buck-Boost topology can operate in both boost and buck modes, thus providing a stable output voltage value for a wide range of input voltages.

[0043] Furthermore, the buck-boost circuit includes a first current sampler CT1; the first current sampler is used to sample the current flowing from the first voltage terminal VIN to the first power switch Q1.

[0044] In this embodiment, the current can be sampled by the first current sampler CT1, and the voltage value at the input voltage terminal and the output voltage value can be sampled at the same time. The PWM duty cycle can be controlled by the sampled current value and voltage value through PID or other control methods to ensure the stability of the output voltage.

[0045] In one possible implementation of this application embodiment, the LLC resonant circuit is a half-bridge LLC resonant circuit. For example... Figure 2 As shown, the control switches in the LLC resonant circuit include a first control switch S1 and a second control switch S2.

[0046] The voltage input terminal of the LLC resonant circuit is connected to the third node through the first control switch S1; the third node is also grounded through the second control switch S2; the third node is connected to the primary input terminal of the transformer T; the primary output terminal of the transformer T is grounded through the resonant capacitor Cr; the secondary side of the transformer T is used to output the target voltage.

[0047] Furthermore, the switch control signal is a high-frequency pulse wave with an output duty cycle of 50%.

[0048] In the half-bridge LLC resonant circuit, the first control switch S1 and the second control switch S2 are alternately turned on at a certain frequency. When the switching control signal is a high-frequency pulse wave with an output duty cycle of 50%, the first control switch S1 and the second control switch S2 can form a high-frequency square wave with a 50% duty cycle. The high-frequency square wave signal is applied to the resonant network.

[0049] Furthermore, the LLC resonant circuit also includes a second current sampler CT2; the second current sampler CT2 is used to sample the current flowing from the voltage input terminal of the LLC resonant circuit to the first control switch S1. The resonant network in the LLC resonant circuit consists of a resonant inductor Lr, a magnetizing inductor Lm, and a resonant capacitor Cr. Through the resonant network, combined with high-frequency drive and frequency control, the LLC resonant circuit can achieve efficient energy transfer and voltage regulation.

[0050] Therefore, in Figure 2 The isolated power supply shown employs a two-stage PWM control strategy. The front stage performs pulse width modulation control on the four-switch BUCKBOOST topology, while the rear stage performs pulse frequency modulation control on the coreless LLC resonant circuit.

[0051] In order to meet the application scenarios of low voltage and high power density Figure 2The first control unit A1 shown can employ a low-frequency PWM control strategy. The front-end power supply uses a closed-loop FPWM control BUCKBOOST topology, with four MOSFETs forming the drive circuit. In this embodiment, by sampling the voltage value Vin of the first voltage terminal VIN, the Iin_sense signal sampled by the first current sampler, and the Icc_sense signal sampled by the second current sampler, combined with a PID control strategy, in the PWM control strategy 1 module, a low-frequency (configurable to 100kHz-1MHz) FPWM signal is output to drive the gate signals of the four MOSFETs, enabling the system to operate in continuous conduction mode. Then, by sampling the voltage of the output capacitor Cb, a closed-loop control is formed on the voltage value of the voltage output terminal VCC of the buck-boost circuit. The voltage of the output capacitor Cb is provided to the subsequent LLC as the input voltage. In this embodiment, the voltage value of the output voltage terminal VCC can be set to 24V to meet the 3-40V requirements of low-voltage applications in automotive electronics.

[0052] like Figure 2 As shown, the power supply stage consists of an LLC resonant circuit and a coreless coil topology. The coreless isolation coil transformer design is suitable for 400V or 800V inverter circuits. Due to the inductance design limitations of the coreless coil, the LLC resonant circuit uses high-frequency SW control with a frequency range of 20MHz-30MHz. The resonant circuit is composed of resonant inductance Lr, magnetizing inductance Lm, and resonant capacitor Cr, where Lm and Lr come from the primary winding of the transformer coil. Lr is the leakage inductance of the primary winding, and Lm is the inductance of the primary winding. The turns ratio of the primary and secondary windings of the transformer T can be designed to be 1:1. The high-frequency resonant circuit generates an AC voltage on the secondary winding of the transformer to achieve high-density power transmission.

[0053] Figure 2 The second control unit A2 shown can adopt a high-frequency PWM control strategy. Since the closed-loop BUCKBOOST output voltage VCC can be relatively constant, Icc_sense and VCC are sampled, and combined with lookup tables and PID control, a frequency control pulse modulation strategy 2 is formed. This strategy is applied to the second group of gate drive modules and outputs a high-frequency pulse wave with a duty cycle of 50%. This pulse wave is then fed to the half-bridge topology formed by the two MOSFETs, the first control switch S1 and the second control switch S2, thereby achieving high power density and low-cost power transmission.

[0054] Figure 3 A power control logic diagram according to an embodiment of this application is shown. Figure 3As shown, in this embodiment, a control strategy combining a PID (Proportional-Integral-Derivative) controller and a Look-Up Table (LUT) can be employed. A look-up table is a storage method that maps input values ​​to output values. When the controller receives various sampled current and voltage values, it can obtain the corresponding PID output through PID control. The PID output is then mapped to the corresponding value through the look-up table, thereby generating the corresponding PWM control strategy. This strategy is used to control the boost / buck circuit and the LLC resonant circuit through the first control unit A1 and the second control unit A2, respectively.

[0055] Furthermore, such as Figure 2 As shown, the input terminal of the secondary side of the transformer is connected to the first voltage terminal, the isolation ground terminal, and the second voltage terminal respectively through a rectifier circuit; the first voltage terminal is used to output the positive target voltage; and the second voltage terminal is used to output the negative target voltage.

[0056] Furthermore, the first end of the secondary side of the transformer is connected to the fourth node through the first diode D1; the fourth node is connected to the second end of the secondary side of the transformer through the first capacitor; the second end of the secondary side of the transformer is connected to the fifth node through the second capacitor; and the fifth node is connected to the first end of the secondary side of the transformer through the second diode D2.

[0057] The fourth node is also connected to the fifth node via a third capacitor; the fourth node is connected to the sixth node via a fourth capacitor; the fourth node is also connected to the sixth node via a first resistor; the sixth node is connected to the fifth node via a fifth capacitor; the sixth node is also connected to the fifth node via a Zener diode Z1.

[0058] The fourth node is connected to the first voltage terminal via the first ferrite bead FB1; the sixth node is connected to the isolation ground terminal SNGD via the second ferrite bead FB2; and the fifth node is connected to the second voltage terminal via the third ferrite bead FB3.

[0059] like Figure 2 As shown, after the high-frequency resonant circuit generates an AC voltage on the secondary side of the transformer, it is regulated by the first diode D1, the second diode D2, and the first to fifth capacitors, resulting in an output voltage of 30V. This voltage then passes through the Zener diode Z1 and the voltage divider resistor circuit R1, achieving a positive output voltage VCC1 at the first voltage terminal and a negative output voltage VEE1 at the second voltage terminal. The positive voltage VCC1 and the negative voltage VEE1 can be used as the secondary power supply for the driver circuit chip, providing high and low level drive to the IGBT or SiC.

[0060] In the isolated power supply shown in the embodiments of this application, the two-stage pulse control strategy employs two loop control loops. However, the signal frequency and power density are strongly reflected in the subsequent LLC stage. Therefore, in this embodiment, a series magnetoresistive resistor can be connected at the input and output to cancel the influence of EMC. In this application, the ferrite bead mainly functions on the isolated output side. The voltage supplied to the driver chip and the signal to the isolation ground are both connected in series with the ferrite bead, such as... Figure 2 The first magnetic bead FB1, the second magnetic bead FB2, and the third magnetic bead FB3 are shown.

[0061] Furthermore, this application also provides a vehicle equipped with an isolated power supply as shown above, which enables high power density transmission at low voltage, thereby providing the vehicle with a high-power low-voltage power supply to realize various functions on the vehicle.

[0062] In summary, the isolated power supply provided in this application includes a buck-boost circuit and an LLC resonant circuit. The buck-boost circuit includes a first control unit, which provides a pulse width modulation signal of a first frequency to the control terminals of each power switch in the buck-boost circuit. The buck-boost circuit can boost or buck the voltage at the first voltage terminal to a specified voltage value according to the selected first frequency and transmit it to the voltage input terminal of the LLC resonant circuit. The LLC resonant circuit includes a second control unit, which provides a switching control signal of a second frequency to each control switch. The LLC resonant circuit can then perform energy transmission at a specified power density according to the selected second frequency. The circuit can provide a stable low-voltage power supply using the pulse width modulation signal of the first frequency, and by increasing the second frequency, high-density power transmission can be achieved, thus realizing high-power-density transmission at low voltage.

[0063] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the utility model disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this application are indicated by the following claims.

[0064] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope.

Claims

1. An isolated power supply, characterized in that, The isolated power supply includes a step-up / step-down circuit and an LLC resonant circuit. The buck-boost circuit includes a first control unit; the first control unit is used to provide a pulse width modulation signal of a first frequency to the control terminal of each power switch in the buck-boost circuit; the voltage input terminal of the buck-boost circuit is connected to a first voltage terminal; the voltage output terminal of the buck-boost circuit is connected to the voltage input terminal of the LLC resonant circuit. The LLC resonant circuit includes a second control unit; the second control unit is used to provide a second frequency switching control signal to each control switch in the LLC resonant circuit; the voltage output terminal of the LLC resonant circuit is used to output a target voltage.

2. The isolated power supply according to claim 1, characterized in that, The power switching transistors in the buck-boost circuit include a first power switching transistor, a second power switching transistor, a third power switching transistor, and a fourth power switching transistor. The voltage input terminal of the buck-boost circuit is connected to the first node through a first power switch; the first node is grounded through a second power switch; the first node is connected to the second node through a first inductor. The second node is connected to the voltage output terminal of the buck-boost circuit via a third power switch; the second node is also grounded via the fourth power switch. The voltage output terminal of the buck-boost circuit is grounded through an output capacitor.

3. The isolated power supply according to claim 2, characterized in that, The buck-boost circuit includes a first current sampler; the first current sampler is used to sample the current flowing from the first voltage terminal to the first power switch.

4. The isolated power supply according to any one of claims 1 to 3, characterized in that, The LLC resonant circuit is a half-bridge LLC resonant circuit.

5. The isolated power supply according to claim 4, characterized in that, Each control switch in the LLC resonant circuit includes a first control switch and a second control switch. The voltage input terminal of the LLC resonant circuit is connected to the third node through the first control switch; the third node is also grounded through the second control switch; the third node is connected to the primary input terminal of the transformer; the primary output terminal of the transformer is grounded through a resonant capacitor; the secondary side of the transformer is used to output the target voltage.

6. The isolated power supply according to claim 5, characterized in that, The switch control signal is a high-frequency pulse wave with a duty cycle of 50%.

7. The isolated power supply according to claim 6, characterized in that, The LLC resonant circuit also includes a second current sampler; the second current sampler is used to sample the current flowing from the voltage input terminal of the LLC resonant circuit to the first control switch.

8. The isolated power supply according to claim 7, characterized in that, The input terminal of the secondary side of the transformer is connected to the first voltage terminal, the isolation ground terminal and the second voltage terminal respectively through a rectifier circuit; The first voltage terminal is used to output a positive target voltage; the second voltage terminal is used to output a negative target voltage.

9. The isolated power supply according to claim 8, characterized in that, The first end of the secondary side of the transformer is connected to the fourth node via a first diode; the fourth node is connected to the second end of the secondary side of the transformer via a first capacitor; the second end of the secondary side of the transformer is connected to the fifth node via a second capacitor; and the fifth node is connected to the first end of the secondary side of the transformer via a second diode. The fourth node is also connected to the fifth node via a third capacitor; the fourth node is connected to the sixth node via a fourth capacitor; the fourth node is also connected to the sixth node via a first resistor; the sixth node is connected to the fifth node via a fifth capacitor; the sixth node is also connected to the fifth node via a Zener diode; The fourth node is connected to the first voltage terminal via the first ferrite bead; the sixth node is connected to the isolation ground terminal via the second ferrite bead. The fifth node is connected to the second voltage terminal via a third magnetic bead.

10. A vehicle, characterized in that, The vehicle is equipped with an isolated power supply as described in any one of claims 1 to 9.

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