CN1352484A - Voltage converter for electric automobile fuel battery unit - Google Patents

Abstract

The invention relates to a voltage transform device of fuel battery group used in electric automobile. It consists of a DC/DC module or multi DC/DC modules and an even current control module. The voltages output from each DC/DC module being connected in parallel and then connected to adjusting end of voltage in the even current control module. The current sense signal output from each DC/DC module is connected to the collected end of current signal of the even current control module. The even current control signal output from the even current control module connects to the input end of the even control signal in each DC/DC module. The DC/DC modules make output power supply of the fuel battery raised to stable power with enough high voltage and high stability, in order to meet the requirement for driving electric automobile. The output voltage of the fuel battery can be adapted to the lower but with large range of variation and its pwoer can be more than 160 KW.

Description

Voltage conversion device for electric vehicle fuel cell stack

technical field

The invention relates to a voltage converting device for a fuel battery pack of an electric vehicle.

Background technique

Research on fuel cells and related technologies has become a hot topic for new technologies in the energy field of great strategic significance in various industrial countries. Fuel cell electric vehicles and related technologies have been listed as major technical issues for priority development by various industrial countries and international automobile industry groups. In the national 863 major project of electric vehicles, fuel cell electric vehicles and related technologies have been listed as key technical research topics. Fuel cell conversion device (hereinafter referred to as DC/DC) is a related technology of fuel cell electric vehicles, and has been listed as a key technical research topic of major electric vehicle projects.

The basic function of DC/DC is to upgrade the lower fuel cell output power with double the voltage fluctuation range to a stable power supply with a sufficiently high voltage range to meet the requirements of the electric vehicle drive and control system for the power supply voltage amplitude and stability. degree requirements. And it must have control characteristics that are well matched with the output characteristics of the fuel cell.

But so far, there have been no reports of fuel cell DC/DC that meet the national 863 major special technical requirements for electric vehicles.

Contents of the invention

The task of the present invention is to provide a power conversion device for a fuel cell stack of an electric vehicle. It can upgrade the fuel cell output power supply with a relatively low voltage fluctuation range and a power of more than 160KW to a stable power supply with a sufficiently high voltage amplitude and high voltage stability to adapt to the electric vehicle drive and control system Requirements for voltage amplitude and stability.

Task of the present invention is realized through the following technical solutions:

A voltage conversion device for an electric vehicle fuel cell stack, which includes a DC/DC module or a plurality of DC/DC modules and a current sharing control module, and the output voltages of each DC/DC module are connected in parallel and then connected to the current sharing control module The voltage adjustment terminal of the DC/DC module, the current detection signal output by each DC/DC module is connected to the current signal acquisition terminal of the current balance control module, and the current balance control signal output by the current balance control module is connected to the current balance control signal input terminal of each DC/DC module.

The DC/DC module is composed of main circuit, control chip, input voltage detection, zero current detection, peak current detection, output voltage detection, switch tube drive signal, output current signal, and current sharing control signal. voltage circuit; input voltage detection, zero current detection, peak current detection, output voltage detection part of the input are connected to the main circuit, the output is connected to the control chip; the input of the switch tube drive signal is connected to the control chip, the output is connected to the main circuit; the output current signal Part of the input is connected to the main circuit; the output of the current sharing control signal part is connected to the input of the output voltage detection part.

The model of the control chip is MC3×262; the main circuit is a booster composed of a filter capacitor, an inductor connected in series in the output circuit of the power supply, a rectifier diode, and a switch tube connected between the rear end of the inductor and the ground of the power supply. voltage circuit; the input voltage detection part is composed of two resistors and a capacitor, the two resistors are connected in series between the positive end of the power supply and the ground, the series point is connected to the 3-terminal of the control chip, and the capacitor is connected to the 3-terminal of the control chip and the ground Between the ground; the zero current detection part is composed of an inductance, a diode, a resistor, and a capacitor that are inductively coupled with the main circuit, and the inductor, the diode, the resistor, and the capacitor are connected in series to the power supply ground in sequence, and the series connection of the resistor and the capacitor is controlled Terminal 8 of the chip, the other terminal of the inductance and the cathode of the diode are connected to the input terminal of the power supply chip, and the output of the power supply chip is connected to terminals 4 and 2 of the control chip; The potentiometer is connected in series with the potentiometer, the output of the current transformer is adjusted by the potentiometer and then connected to the 5-terminal of the control chip; the output voltage detection part is composed of a resistor connected to the output of the main circuit and a potentiometer, and the adjustment terminal of the potentiometer is connected to the control chip 1 terminal of the switch tube; the switch tube drive signal is provided to the control terminal of the switch tube by the 7 terminals of the control chip; the output current signal part is formed by a current transformer connected to the output of the main circuit; the current equalization control signal part is composed of An optocoupler is formed, and its output is connected to terminals 1 and 4 of the control chip.

The current equalization control module is composed of control chips UC3902 equal in number to the DC/DC modules, wherein: the current signal acquisition terminal of each control chip is connected to the output current signal end of the corresponding DC/DC module; the current equalization control signal of each control chip Connect to the current equalization control terminal of the corresponding DC/DC module; the voltage adjustment terminals of each control chip are connected in parallel and then connected to the voltage output terminals of each DC/DC module.

The present invention adopts several DC/DC modules composed of novel boost control circuits, and a low-power DC/DC device can be composed of one DC/DC module, or several DC/DC modules and a current equalizing module can be composed of several DC/DC modules with an input voltage of 50V-400V, high-power DC/DC devices for fuel cell electric vehicles with a variety of rated voltages and rated powers with a rated output power of up to 160KW.

Since the main circuit of the present invention adopts a novel boost conversion circuit, compared with the commonly used full-bridge conversion circuit, this circuit not only has the characteristics of simple structure, but also has high conversion efficiency (conduction loss is more than doubled), and the voltage is increased. The outstanding advantage of the large degree of freedom of the amplitude (the voltage conversion range of the same device can be set arbitrarily within the range of 2.4-7 times).

Because the control system of the present invention adopts MC3×262 high-performance new PCF integrated controller, the circuit with zero-current switch function is composed of the controller, which not only greatly reduces the system loss, improves the efficiency, but also reduces the internal power of the device. According to the technical requirements of switching devices, lower-priced low-speed devices can be used to assemble higher-frequency high-power DC/DC, which also greatly reduces the switching noise of system power devices and the electromagnetic disturbance of the whole machine, which is beneficial to improving the overall vehicle performance. Electromagnetic disturbance performance plays an important role.

The special structure of the device of the invention realizes the ultra-wide input and output voltage range that other similar devices do not possess. The input voltage of each module can be varied within a wide range of 50V-400V, and the output voltage can be set arbitrarily within a wide range of 120V-460V.

The device of the present invention adopts a modular structure and a current equalizing circuit, and can be independently formed by a DC/DC module into a low-power DC/DC device, and can also be composed of several DC/DC modules to form DCs with various rated powers up to 160KW or more. /DC devices to meet the power requirements of electric vehicles with different power levels for DC/DC devices.

Description of drawings

Figure 1 is an electrical schematic diagram of a low-power DC/DC device composed of a single DC/DC module;

Fig. 2 is a structural block diagram of the DC/DC module of the present invention;

Fig. 3 is the schematic diagram of the DC/DC module of the present invention;

Fig. 4 is a schematic diagram of the high-power DC/DC device composed of a plurality of DC/DC modules of the present invention;

Figure 5 is an electrical schematic diagram of a high-power DC/DC device composed of multiple DC/DC modules;

Fig. 6 is an electrical schematic diagram of the current sharing control module of the present invention.

Detailed ways

The present invention is a power conversion device for electric vehicle fuel cell packs, which can be composed of a DC/DC module to form a low-power voltage conversion device below 30KW, and can also be composed of several DC/DC modules connected in parallel and a current sharing control module. High-power power conversion devices up to 160KW or more.

Referring to Figure 1, the diagram shows a low-power power conversion device composed of a DC/DC module. The unstable power output from the fuel cell is input through terminals 201 and 202, and after DC/DC conversion, it is output through terminals 203 and 204 to the power input terminal of the electric vehicle.

Referring to Figure 2, the DC/DC module is composed of main circuit, control chip, input voltage detection, zero current detection, peak current detection, output voltage detection, switching tube drive signal, output current signal, and current sharing control signal. Among them: the main circuit is a boost circuit; the input of the input voltage detection, zero current detection, peak current detection, and output voltage detection parts are all connected to the main circuit, and the output is connected to the control chip; the input of the switch tube drive signal is connected to the control chip, and the output is connected to the control chip. The main circuit; the input of the output current signal part is connected to the main circuit; the output of the current sharing control signal part is connected to the input of the output voltage detection part.

Refer to Figure 3. The DC/DC module boost conversion main circuit is composed of filter capacitors C201 and C202, boost inductor L201 connected in series in the power output circuit, rectifier diode D202, and switch tube T201 connected between the back end of the inductor L201 and the power ground the boost circuit. The step-up ratio of the DC/DC converter composed of this circuit can be as large as 7 times the input voltage, and has extremely low conduction loss.

U201 (MC3×262) is the controller of the DC/DC converter.

The input voltage detection part is composed of resistors R201, R204 and capacitor C203. The resistors R201 and R204 are connected in series between the positive terminal of the power supply and the ground. The series point is connected to the 3rd terminal of the control chip U201, and the capacitor C203 is connected to the 3rd terminal of the control chip U201. between end and ground.

The zero current detection part is composed of an inductor coupled with the inductor L201 of the main circuit, a diode D201, a resistor R203 and a capacitor C204. Terminal 8 of the control chip U201, the other terminal of the inductor and the cathode of the diode D201 are connected to the input terminal of the power chip POWER, and the output of the power chip POWER is connected to terminals 4 and 2 of the control chip U201.

The peak current detection part is composed of a current transformer LEM201 connected in series with the potentiometer W202 connected to the back end of the inductor in the main circuit. The output of the current transformer is adjusted by the potentiometer and then connected to the 5-terminal of the control chip U201.

The output voltage detection part is composed of a resistor R206 connected to the output of the main circuit and a potentiometer W201, and the adjustment terminal of the potentiometer is connected to terminal 1 of the control chip U201.

The switch tube driving signal is provided by the control chip U201 terminal 7 to the control terminal of the switch tube T201.

The output current signal part is composed of the current sensor LEM202 connected to the output of the main loop.

The current control signal part is composed of optocoupler U202, and its output is connected to terminals 1 and 4 of the control chip.

The power circuit composed of L201, D201, POWER and C205 provides control power to the control circuit with the control chip U201 as the core. The input voltage range of POWER is very wide, and it can be used in any voltage range of 50V-500V. The output voltage of POWER changes with the current in the inductor L201.

The working principle of the DC/DC module is: the power input voltage signal is input from the control chip U201-3 through the coupling circuit composed of R201, R204 and C203; the zero current signal is input from the control chip U201-3 through the coupling circuit composed of L201, R203 and C204 8 inputs; the output voltage signal is input from the control chip U201-1 through the voltage detection circuit composed of R206 and W201; the peak current is input from the control chip U201-5 through the detection circuit composed of current transformers LEM201 and W202; LEM202 provides The output current signal of this DC/DC module; U202 receives the current sharing control signal of the current sharing module. After the above-mentioned input signals are input to U201, control signals are generated and output from U201-7 to control the switching tube T201 to realize voltage boost conversion control.

It is one of the notable features of this DC/DC converter to set up a zero-current detection circuit to realize zero-current switching. Zero current switching can greatly reduce switching loss and electromagnetic disturbance.

Referring to Fig. 4, the diagram shows a high-power DC/DC converter up to 160KW composed of several DC/DC modules (DC/DC-1~DC/DC-5) connected in parallel and a current sharing control module JMK2. The power input terminals (INPUT+/-) of each DC/DC module are connected in parallel to the power input terminals 101 and 102 of the power conversion system, and the output terminals (OUT+/-) are connected in parallel to the output terminal 103 of the power conversion device and 104.

Each DC/DC module has independent voltage boost power control and characteristic matching control functions. The function of the current sharing control module is to make the DC/DC conversion device output any power when multiple modules are connected in parallel, so that each DC/DC module can achieve power balance output, and prevent individual DC/DC The module outputs more power than other DC/DC modules.

The control terminals of the DC/CD-1~DC/DC-5 modules are respectively connected to the 3×1, 3×2, 3×3, 3×4 of the current sharing control module JMK2 via terminals 208, 207, 205 and 206, The terminals 309 and 310 of the current equalization control module JMK2 are connected to the output terminals 204 and 203 of the DC/DC conversion device.

The current sharing control module JMK2 inputs the output current signal of each parallel module from 3×3, and the bus voltage output by the DC/DC converter from 309 and 310, and outputs control signals from 3×1 and 3×2 after being processed by module JMK2 , to control the output power of each DC/DC module, so that each DC/DC module can equally share the total output power of the DC/DC device.

Fig. 5 is also the input terminal of a high-power DC/DC device composed of multiple DC/DC modules, but the power input terminals (INPUT+/-) of each DC/DC module are connected to the independent output power of each fuel cell.

Referring to Figure 6, the current sharing control module is composed of control chips UC3902 (U301~U305) equal in number to the DC/DC module, wherein: the current signal acquisition terminal 3 of each control chip U30x is connected to the output current signal terminal of the corresponding DC/DC module The voltage adjustment terminals 6 and 7 of each control chip are connected in parallel and then connected to the voltage output terminals of each DC/DC module; the current equalization control signal terminals 1 and 2 of each control chip U30x are connected to the current equalization control terminal of the corresponding DC/DC module.

Its working principle is: the output current signal of each DC/DC module is input from 3×3, coupled to U30x-3 through resistor R3×1, and the output bus voltage of each DC/DC module is input from 309, 310 to U30x-6 and U30x-7, the current sharing control signal sent by each control chip U30x is output to each DC/DC module through 3×1 and 3×2.

Claims (4)

1. A voltage conversion device for an electric vehicle fuel cell stack, characterized in that: It includes a DC/DC module, which is composed of main circuit, control chip, input voltage detection, zero current detection, peak current detection, output voltage detection, switch tube drive signal, output current signal, and current sharing control signal. : The main circuit is a boost circuit; Input voltage detection, zero current detection, peak current detection, output voltage detection part of the input are connected to the main circuit, the output is connected to the control chip; The input of the switch tube drive signal is connected to the control chip, and the output is connected to the main circuit; The input of the output current signal part is connected to the main circuit; The output of the current sharing control signal part is connected to the input of the output voltage detection part. 2. The voltage conversion device for electric vehicle fuel cell stack as claimed in claim 1, characterized in that: It includes multiple DC/DC modules and a current sharing control module. The voltage output by each DC/DC module is connected in parallel to the voltage adjustment terminal of the current sharing control module, and the current detection signal output by each DC/DC module is connected to the current sharing control module. The current signal acquisition terminal of the current balance control module is connected to the current balance control signal input terminal of each DC/DC module. 3. The voltage conversion device for an electric vehicle fuel cell stack as claimed in claim 1 or 2, characterized in that: The model of the control chip is MC3×262; The main circuit is a boost circuit composed of a filter capacitor, an inductance connected in series in the output circuit of the power supply, a rectifier diode, and a switch tube connected between the rear end of the inductor and the ground of the power supply; The input voltage detection part is composed of two resistors and a capacitor, the two resistors are connected in series between the positive terminal of the power supply and the ground, the series connection point is connected to the 3 terminals of the control chip, and the capacitor is connected between the 3 terminals of the control chip and the ground ; The zero-current detection part is composed of an inductance, a diode, a resistor, and a capacitor that are inductively coupled with the main circuit. The inductor, the diode, the resistor, and the capacitor are connected in series in sequence to the power supply ground, and the series connection of the resistor and the capacitor is connected to 8 terminals of the control chip. , the other end of the inductor and the cathode of the diode are connected to the input end of the power chip, and the output of the power chip is connected to terminals 4 and 2 of the control chip; The peak current detection part is composed of a current transformer connected in series with a potentiometer connected to the inductance rear end in the main circuit, and the output of the current transformer is adjusted by the potentiometer and then connected to the 5 terminals of the control chip; The output voltage detection part is composed of a resistor connected to the output of the main circuit and a potentiometer, and the adjustment terminal of the potentiometer is connected to terminal 1 of the control chip; The switch tube drive signal is provided to the control terminal of the switch tube by the 7-end of the control chip; The output current signal part is composed of a current transformer connected to the output of the main loop; The current equalization control signal part is composed of an optocoupler, and its output is connected to terminals 1 and 4 of the control chip. 4. The voltage conversion device for an electric vehicle fuel cell stack as claimed in claim 2, characterized in that: The current sharing control module is composed of a control chip UC3902 equal in number to the DC/DC module, wherein: The current signal acquisition terminal of each control chip is connected to the output current signal terminal of the corresponding DC/DC module; The current sharing control signal of each control chip is connected to the current sharing control terminal of the corresponding DC/DC module; The voltage adjustment terminals of each control chip are connected in parallel and then connected with the voltage output terminals of each DC/DC module.

Images