Bidirectional DC-DC converter circuit

Abstract

A bidirectional DC-DC converter circuit relates to the technical field of converters and comprises a control board, a main sampling circuit, a driving circuit and a main circuit, and the control board takes a DSP28069 minimum system board as a core. An ADC sampling circuit, an enhanced EPWM generation circuit, a four-corner switch circuit, a hardware voltage protection circuit, a detection current TZ software protection circuit, a liquid crystal display circuit, a serial port communication circuit and a reference voltage source circuit are carried. By adopting the synchronous two-switch BUCK-BOOST structure, high-efficiency energy conversion can be realized, the energy loss is obviously reduced, the overall energy efficiency of the system is improved, the structure allows current to synchronously flow between the two switches, and the sudden change of the current is reduced, so that the ripple of the output voltage is reduced, the low-ripple output of the circuit design is realized, and the power consumption of the system is reduced. The stability of the power supply and the reliability of load equipment are improved, and the service life of the equipment is prolonged.

Description

Technical Field

[0001] The utility model relates to the technical field of converters, in particular to a bidirectional DC-DC converter circuit. Background Art

[0002] A DC-DC converter is a device that converts a DC power source at one voltage level to a DC power source at another voltage level. These converters are widely used in various electronic devices to meet the varying power supply voltage requirements of different components. Traditional converters generally include step-down converters and boost converters. With technological advancements, bidirectional DC-DC converters have emerged. These converters not only enable step-up and step-down voltage conversion but also enable bidirectional energy transfer between different power sources and loads.

[0003] However, traditional bidirectional DC-DC converters are inefficient at high power output, especially under high load conditions, resulting in significant losses during the energy conversion process. Furthermore, the output voltage ripple is large during the energy conversion process, which can affect load stability and device lifespan. To achieve bidirectional energy flow and voltage conversion, existing technologies often require complex hardware configurations, increasing costs and system instability. Utility Model Content

[0004] The purpose of the utility model is to provide a bidirectional DC-DC converter circuit to achieve high efficiency and low ripple output, and to simplify the structure to reduce costs and improve system reliability.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solution: a bidirectional DC-DC converter circuit includes a control board, a main sampling circuit, a drive circuit and a main circuit.

[0006] The control board is based on the DSP28069 minimum system board and is equipped with an ADC sampling circuit, an enhanced EPWM generation circuit, a four-corner switch circuit, a hardware voltage protection circuit, a current detection TZ software protection circuit, a liquid crystal display circuit, a serial communication circuit, and a reference voltage source circuit.

[0007] The control board is connected to the liquid crystal display circuit via a serial communication circuit to enable parameter display and setting. The control board is connected to the drive circuit via a four-corner switch circuit to control the power devices in the main circuit. The topology of the main circuit is a synchronous two-switch buck-boost DC conversion circuit structure. The control board is connected to the main sampling circuit via an ADC sampling circuit to sample the input and output voltages and currents. The main sampling circuit transmits the sampled voltage and current signals to the control board. Based on these signals, the control board generates control signals via an enhanced EPWM generation circuit, and controls the switching states of the power devices in the main circuit via the drive circuit, achieving voltage conversion and bidirectional energy flow.

[0008] Preferably, the main sampling circuit includes a current sampling circuit and a voltage acquisition circuit. The current sampling circuit adopts an ACS712ELCTR Hall effect linear current sensor, and the voltage acquisition circuit is an isolated differential sampling circuit using an AMC1311 precision voltage detection enhanced isolation amplifier.

[0009] More preferably, the driving circuit adopts a UCC21520 isolation driving chip.

[0010] More preferably, the power device in the main circuit is a STB15810 N-channel MOS tube.

[0011] More preferably, the ADC sampling circuit is equipped with hardware low-pass filtering to filter out high-order harmonics.

[0012] Compared to existing technologies, this utility model utilizes a synchronous two-switch buck-boost structure, achieving high-efficiency energy conversion, significantly reducing energy loss and improving the overall energy efficiency of the system. Furthermore, this structure allows current to flow synchronously between the two switches, reducing current fluctuations and, consequently, output voltage ripple. This allows the circuit design to achieve low-ripple output, improving power supply stability and load device reliability, thereby extending the device's service life. By optimizing the hardware design, costs are reduced and system reliability is improved, making the circuit more economical and practical. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 Schematic diagram of the circuit structure in the embodiment;

[0014] Figure 2 Schematic diagram of the structure of the main circuit in the embodiment;

[0015] Figure 3 Schematic diagram of the structure of the driving circuit in the embodiment;

[0016] Figure 4 Schematic diagram of the structure of the current sampling circuit in the embodiment;

[0017] Figure 5 Schematic diagram of the structure of the voltage acquisition circuit in the embodiment;

[0018] Figure 6 Schematic diagram of the structure of the liquid crystal display circuit in the embodiment;

[0019] Figure 7 Schematic diagram of the structure of the four-corner switch circuit in the embodiment;

[0020] Figure 8 Schematic diagram of the structure of the ADC sampling circuit in the embodiment;

[0021] Figure 9 Schematic diagram of the circuit structure of the control board in the embodiment;

[0022] Figure 10 Schematic diagram of the overall control circuit structure in the embodiment. DETAILED DESCRIPTION

[0023] In order to facilitate understanding by those skilled in the art, the present invention is further described below with reference to embodiments and drawings. The contents mentioned in the embodiments are not intended to limit the present invention.

[0024] like Figure 1 As shown, a bidirectional DC-DC converter circuit includes a control board, a main sampling circuit, a drive circuit, and a main circuit; the control board is based on the DSP28069 minimum system board and is equipped with an ADC sampling circuit, an enhanced EPWM generation circuit, a four-corner switch circuit, a hardware voltage protection circuit, a current detection TZ software protection circuit, a liquid crystal display circuit, a serial communication circuit, and a reference voltage source circuit.

[0025] The DSP28069 minimum system board features a 90MHz processing speed, 16×16 and 32×32 multiplication and accumulation (MAC) capabilities, linked operations, fast interrupt response and processing, a floating-point unit (FPU), a programmable control law accelerator (CLA), a 32-bit floating-point math accelerator, and up to eight enhanced pulse width modulator (ePWM) modules.

[0026] In the above circuit structure, the control board is connected to the liquid crystal display circuit via a serial communication circuit to enable parameter display and setting. The control board is connected to the drive circuit via a four-corner switch circuit to control the power devices in the main circuit. The main circuit topology is a synchronous two-switch buck-boost DC conversion circuit structure. The control board is connected to the main sampling circuit via an ADC sampling circuit to sample the input and output voltages and currents. The main sampling circuit transmits the sampled voltage and current signals to the control board. Based on these signals, the control board generates control signals via an enhanced EPWM generation circuit. The control board controls the switching state of the power devices in the main circuit via the drive circuit, achieving voltage conversion and bidirectional energy flow.

[0027] like Figure 8 As shown in Figure 1, the ADC sampling circuit is equipped with hardware low-pass filtering and voltage and current protection circuits. This filter can effectively filter out high-order harmonics and reduce the high-frequency noise generated by switching operations, thereby further reducing the output voltage ripple.

[0028] The main sampling circuit in this embodiment includes a current sampling circuit and a voltage sampling circuit, such as Figure 4 As shown in the figure, the current sampling circuit uses the ACS712ELCTR Hall effect linear current sensor, which has circuit isolation, supports 20A current input, 5V supply voltage, sensitivity 297mV / A, frequency DC ~ 80kHz linearity: ±1.5, accuracy: ±1.5%, 5μs, which is sufficient to meet the design requirements. Figure 5 As shown, the voltage acquisition circuit is an isolated differential sampling circuit using the Ti AMC1311 precision voltage detection reinforced isolated amplifier. It supports a 2V input and can adjust the input voltage accuracy and range by adjusting the value of the sense resistor. The resistors configured in this detection circuit are 3kΩ and 97kΩ, enabling 67V and 33V / mV detection.

[0029] like Figure 3 As shown in the figure, the drive circuit uses the UCC21520 isolated driver chip, a 5.7kVRMS 4A dual-channel isolated gate driver with dual-pin input and disable pin.

[0030] like Figure 2 As shown in the figure, the main circuit topology is a bidirectional DCDC synchronous buck-boost DC conversion circuit, which supports bidirectional energy flow and uses MOS instead of diodes to reduce the conduction power of the power device. The power device is an STB15810 N-channel MOS transistor with a drain-source voltage of 100V, a continuous drain current of 110A, and an on-resistance of 3.9mΩ.

[0031] The bidirectional DC-DC converter circuit provided in the above embodiment adopts a synchronous two-switch BUCK-BOOST structure to achieve high-efficiency energy conversion, significantly reduce energy loss, and improve the overall energy efficiency of the system. This circuit structure supports bidirectional DCDC energy flow, so that the circuit can not only realize voltage step-up and step-down conversion, but also transmit energy bidirectionally between different power supplies and loads, which is suitable for application scenarios such as energy recovery of new energy vehicles. Its BUCK mode supports range adjustment from 0 to input voltage, and BOOST mode supports range adjustment from input voltage to three times the input voltage. The maximum voltage of the two modes is 64V, which enables the circuit to adapt to a wider range of application requirements. In addition, through high-precision ADC sampling circuit and enhanced EPWM generation circuit, precise control of input and output voltages and currents is achieved, which improves the control accuracy of the circuit.

[0032] In order to make it easier for ordinary technicians in this field to understand the improvements of the present invention over the prior art, some drawings and descriptions of the present invention have been simplified, and the above-mentioned embodiments are better implementation schemes of the present invention. In addition, the present invention can also be implemented in other ways. Any obvious replacement without departing from the concept of the present technical solution is within the scope of protection of the present invention.

Claims

1. A bidirectional DC-DC converter circuit, characterized in that: Including control board, main sampling circuit, drive circuit and main circuit; The control board is based on the DSP28069 minimum system board and is equipped with an ADC sampling circuit, an enhanced EPWM generation circuit, a four-corner switch circuit, a hardware voltage protection circuit, a current detection TZ software protection circuit, a liquid crystal display circuit, a serial communication circuit, and a reference voltage source circuit. The control board is connected to the liquid crystal display circuit via a serial communication circuit to enable parameter display and setting. The control board is connected to the drive circuit via a four-corner switch circuit to control the power devices in the main circuit. The topology of the main circuit is a synchronous two-switch buck-boost DC conversion circuit structure. The control board is connected to the main sampling circuit via an ADC sampling circuit to sample the input and output voltages and currents. The main sampling circuit transmits the sampled voltage and current signals to the control board. Based on these signals, the control board generates control signals via an enhanced EPWM generation circuit, and controls the switching states of the power devices in the main circuit via the drive circuit, achieving voltage conversion and bidirectional energy flow.

2. The bidirectional DC-DC converter circuit according to claim 1, wherein: The main sampling circuit includes a current sampling circuit and a voltage acquisition circuit. The current sampling circuit adopts the ACS712ELCTR Hall effect linear current sensor, and the voltage acquisition circuit is an isolated differential sampling circuit using the AMC1311 precision voltage detection enhanced isolation amplifier.

3. The bidirectional DC-DC converter circuit according to claim 1, wherein: The driving circuit adopts the UCC21520 isolation driving chip.

4. The bidirectional DC-DC converter circuit according to claim 1, wherein: The power device in the main circuit is selected as STB15810N-channel MOS tube.

5. The bidirectional DC-DC converter circuit according to claim 1, wherein: The ADC sampling circuit is equipped with hardware low-pass filtering to filter out high-order harmonics.

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