CN117439243A - Pre-charging circuit, direct-current voltage converter and fuel cell system comprising same - Google Patents

Pre-charging circuit, direct-current voltage converter and fuel cell system comprising same Download PDF

Info

Publication number
CN117439243A
CN117439243A CN202210817440.0A CN202210817440A CN117439243A CN 117439243 A CN117439243 A CN 117439243A CN 202210817440 A CN202210817440 A CN 202210817440A CN 117439243 A CN117439243 A CN 117439243A
Authority
CN
China
Prior art keywords
voltage
precharge circuit
bus capacitor
signal
power
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202210817440.0A
Other languages
Chinese (zh)
Inventor
路正曦
黄桂根
刘新超
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Robert Bosch GmbH
Original Assignee
Robert Bosch GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Robert Bosch GmbH filed Critical Robert Bosch GmbH
Priority to CN202210817440.0A priority Critical patent/CN117439243A/en
Publication of CN117439243A publication Critical patent/CN117439243A/en
Pending legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/34—Parallel operation in networks using both storage and other dc sources, e.g. providing buffering
    • H02J7/342—The other DC source being a battery actively interacting with the first one, i.e. battery to battery charging
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/0042—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries characterised by the mechanical construction
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/14—Arrangements for reducing ripples from dc input or output
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
    • H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M5/00—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases
    • H02M5/02—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc
    • H02M5/04—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc by static converters
    • H02M5/10—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc by static converters using transformers

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Dc-Dc Converters (AREA)

Abstract

There is provided a precharge circuit including: a power manager having: the power input end, the driving end, the compensation end and the feedback end which is grounded; a switch is provided with: the control end, the first connecting end for outputting the switch signal and the second connecting end; a filter includes: an input terminal and an output terminal for outputting an analog level signal; a voltage follower has: an input end for receiving an analog level signal, an output end for outputting the analog level signal, and another input end connected with the output end; a feedback compensator includes: an input terminal for receiving an analog level signal, another input terminal for receiving a divided voltage signal, and an output terminal for outputting a compensation signal to a compensation terminal of the power manager; and a transformer having a primary winding and an auxiliary winding on a low voltage side and a secondary winding on a high voltage side, the secondary winding being coupled with the dc bus capacitor to precharge the dc bus capacitor.

Description

Pre-charging circuit, direct-current voltage converter and fuel cell system comprising same
Technical Field
The present invention relates to the field of power electronics, and more particularly, to a precharge circuit for precharging a direct current bus Capacitor (DC-Link Capacitor), and a direct current voltage converter and a fuel cell system including the precharge circuit.
Background
Today, low-carbon electricity consumption and intelligent electricity consumption are trends, which place demands on the power electronic converter to achieve various voltage levels. For example, in the electric automotive industry, a combination power converter of multiple power electronic converters that is versatile and scalable is needed to meet a variety of dc power requirements. In this combined power converter, the problem of pre-charging the dc bus capacitor becomes a new bottleneck.
One existing solution for this is to provide a series resistor and mechanical switch on the dc bus to precharge the dc bus capacitor. However, the resistor needs to occupy space, and the mechanical switch has a life problem. In addition, this existing solution also requires housing the resistor and the mechanical switch in a housing, and design the isolation and harness arrangement, with the problems of high cost and complex structure.
Disclosure of Invention
In this context, according to one aspect of the present invention, there is provided a precharge circuit for precharging a dc bus capacitor, comprising: a power manager having: the power input end is connected with the low-voltage power supply to receive input power, the driving end outputs a driving signal, the compensation end receives a compensation signal and the feedback end is grounded; a switch is provided with: a controlled end for receiving the driving signal, a first connection end for outputting a switching signal, and a second connection end grounded via a shunt resistor; a filter includes: an input end for receiving a PWM signal and an output end for outputting an analog level signal; a voltage follower has: an input end for receiving the analog level signal, an output end for outputting the analog level signal, and another input end connected with the output end; a feedback compensator includes: an input terminal for receiving the analog level signal, another input terminal for receiving a divided voltage signal, and an output terminal for outputting the compensation signal to a compensation terminal of the power manager; and a transformer having a primary winding and an auxiliary winding on a low voltage side, the primary winding being coupled between the low voltage power supply and a first connection terminal of the switch, the auxiliary winding being coupled between the other input terminal of the compensator and ground, the secondary winding being coupled with the dc bus capacitor to precharge the dc bus capacitor.
According to another aspect of the invention, there is provided a direct current voltage converter comprising: a power system including a dc bus capacitor; and a control system coupled to the power system, including a precharge circuit as described above, for controlling the precharge circuit to precharge the dc bus capacitor.
According to still another aspect of the present invention, there is provided a fuel cell system including: a fuel cell stack; a high voltage battery; a dc voltage converter as described above coupled between the fuel cell stack and the high voltage battery, including a dc bus capacitor; and a contactor coupled between the fuel cell stack and the dc voltage converter or between the dc voltage converter and the high voltage battery, the contactor configured to be opened at the beginning of the switching of the dc voltage converter into the fuel cell system and to be closed after the precharge of the dc bus capacitor is completed.
The foregoing presents a simplified summary of the invention in order to provide a basic understanding of such aspects. This summary is not intended to describe key or critical elements of all aspects of the invention nor is it intended to limit the scope of any or all aspects of the invention. The purpose of this summary is to present an implementation of these aspects in a simplified form as a prelude to the detailed description that is presented later.
Drawings
Fig. 1A-1C are schematic block diagrams of some examples of fuel cell systems according to an embodiment of the invention.
Fig. 2A-2C are schematic block diagrams of some examples of fuel cell systems according to another embodiment of the invention.
Fig. 3 is a schematic block diagram of a dc voltage converter according to an embodiment of the invention.
Fig. 4 is a schematic diagram of a precharge circuit according to an embodiment of the present invention.
Detailed Description
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
According to an embodiment of the present invention, there is provided a fuel cell system including: a fuel cell stack, a high voltage battery, a direct current voltage converter, and a contactor. The dc voltage converter is coupled between the fuel cell stack and the high voltage battery and includes a dc bus capacitor that requires pre-charging before the contactor is closed. The contactor is coupled between the DC voltage converter and the high voltage battery. The contactor is opened at the beginning of the dc voltage converter switching in the fuel cell system and is closed after the dc bus capacitor has completed the precharge (e.g., is precharged to a predetermined voltage). This arrangement is advantageous because: if the contactor is closed in the presence of a large voltage difference between the fuel cell stack and the high voltage battery, a large impact may be generated at the moment of closing the contactor, causing device damage or cell damage.
Fig. 1A to 1C show some examples of this embodiment.
Fig. 1A shows an example according to this embodiment. Referring to fig. 1A, the fuel cell system includes a direct-current voltage converter 1 (see DC-DC 1 in fig. 1A), a fuel cell stack 2 (see S in fig. 1A) fuel-cell 2) High-voltage battery 3 (see B in FIG. 1A high-voltage 3) And a contactor 4 (see CON 4 in fig. 1A). The dc voltage converter 1 includes a dc bus capacitor 200. The contactor 4 is connected in a positive high voltage line of the fuel cell system, and is connected between the direct-current voltage converter 1 and the high voltage battery 3.
Fig. 1B shows another example according to this embodiment. Referring to fig. 1B, this embodiment is substantially similar to the embodiment of fig. 1A, except that the contactor 4 'in fig. 1B (see CON 4' in fig. 1B) is connected in the negative high-voltage line of the fuel cell system and between the dc voltage converter 1 and the high-voltage battery 3
According to the embodiment of fig. 1A and 1B, when the contactor 4 or 4' is opened, a discharging condition of the dc voltage converter 1 can be achieved, ensuring that the voltage between the positive and negative high voltage lines of the dc voltage converter 1 is reduced to be within a safe range. The embodiments of fig. 1A and 1B are particularly suitable for application scenarios involving several sub-components in a high voltage main network.
Fig. 1C shows yet another example according to this embodiment. Referring to fig. 1C, this embodiment is substantially similar to the embodiment of fig. 1A or 1B, except that the fuel cell system in fig. 1C includes two contactors, i.e., contactors 4 and 4 'in fig. 1C (see CON 4 and CON 4' in fig. 1C), connected in a positive high-voltage line and a negative high-voltage line of the fuel cell system, respectively, and both contactors are connected between the dc voltage converter 1 and the high-voltage battery 3.
The embodiment of fig. 1C is particularly suited for use between two onboard high voltage systems of an electric vehicle having safety isolation requirements. For example, between the main bus bars of two onboard high voltage systems of an electric vehicle, such as between the main bus bar of a high voltage power system and the main bus bar of a fuel cell system, or between the main bus bar of a power cell and the main bus bar of a high voltage power system. When the contactors 4 and 4' in the positive high voltage line and the negative high voltage line are both disconnected, no conductor is directly connected between the two vehicle-mounted high voltage systems, so that absolute high voltage isolation between the two vehicle-mounted high voltage systems is ensured. In addition, when one contactor 4 or 4' of the two contactors is adhered, the other contactor is disconnected, so that the discharging condition of the direct-current voltage converter 1 can be achieved, and the high-voltage safety of the direct-current converter 1 is ensured.
According to another embodiment of the present invention, there is provided a fuel cell system similar to the fuel cell system of the above embodiment except that the contactor in this embodiment is provided between the fuel cell stack and the dc voltage converter instead of between the dc voltage converter and the high voltage battery.
Fig. 2A-2C show some examples of this further embodiment.
Fig. 2A shows an example according to this further embodiment. Referring to fig. 2A, the fuel cell system includes a direct-current voltage converter 1 (seeDC-DC 1 in FIG. 2A), a fuel cell stack 2 (see Sfuel-cell 2 in FIG. 2A), a high voltage battery 3 (see B in FIG. 2A) high-voltage 3) And a contactor 4 (see CON 4 in fig. 2A). The dc voltage converter 1 includes a dc bus capacitor 200. The contactor 4 is connected in the positive high-voltage line of the fuel cell system, and is connected between the fuel cell stack 2 and the dc voltage converter 1.
Fig. 2B shows another example according to this embodiment. Referring to fig. 2B, this embodiment is substantially similar to the embodiment of fig. 2A, except that a contactor 4 'in fig. 1B (see CON 4' in fig. 2B) is connected in the negative high-voltage line of the fuel cell system and between the fuel cell stack 2 and the dc voltage converter 1.
Similar to the embodiment of fig. 1A and 1B, when the contactor 4 or 4' is opened, a discharge condition of the dc voltage converter 1 can be achieved, ensuring that the voltage between the positive and negative high voltage lines of the dc voltage converter 1 is reduced to within a safe range. The embodiments of fig. 2A and 2B are particularly suitable for application scenarios involving several sub-components in a high voltage main network.
Fig. 2C shows yet another example according to this embodiment. Referring to fig. 2C, this embodiment is substantially similar to the embodiment of fig. 2A or 2B, except that the fuel cell system in fig. 2C includes two contactors, i.e., contactors 4 and 4 'in fig. 2C (see CON 4 and CON 4' in fig. 2C), which are connected in the positive high voltage line and the negative high voltage line of the fuel cell system, respectively, and both contactors are connected between the fuel cell stack 2 and the dc voltage converter 1.
Similar to the embodiment of fig. 1C, the embodiment of fig. 2C is particularly suitable for use in applications where safety isolation is required, such as, for example, in an electric vehicle.
Fig. 3 shows a dc voltage converter according to an embodiment of the invention. For example, the DC voltage converter 1 of FIGS. 1A-1C and 2A-2C may be implemented as shown in FIG. 3. As shown in fig. 3, the direct-current voltage converter 1 (see DC-DC 1 in fig. 3) includes a power system 12 (see sys_power 12 in fig. 3) and a control system 11 (see sys_control 11 in fig. 3). The power system 12 is subject to high pressure and delivers power. The power system 12 includes a direct current bus capacitor 200 (see c_dc Link 200 in fig. 3). Power system 12 may also include IGBTs (insulated gate bipolar transistors), MOSFETs (metal oxide semiconductor field effect transistors), inductors, connectors, and so forth. The control system 11 functions as control and drive. The control system 11 includes a precharge circuit 100 (see c_pre-charge 100 in fig. 3). The control system 11 may also include an MCU, sampling circuitry, and driving circuitry, among others.
Fig. 4 illustrates a precharge circuit 100 according to an embodiment of the present invention for precharging a dc bus capacitor 200, for example, charging the dc bus capacitor 200 to a predetermined voltage (i.e., a desired charging voltage). As shown in fig. 4, the precharge circuit 100 includes: a power manager 102, a switch 104, a filter 106, a voltage follower 108, a feedback compensator 110, a voltage divider circuit 112, a transformer 114, a rectifier circuit 116, a passive load 118, and a high frequency filter capacitor 120.
The power manager 102 has: the power input terminal VIN, the driving terminal DR, the compensation terminal COMP, the ground terminal GND, the feedback terminal FB, and the enable terminal FA/SD. The power input VIN is coupled to the low voltage power supply p_lv and receives the input power. The low voltage power source p_lv may include one or more batteries. The low voltage power supply P LV is for example between 9-36V. The low voltage power supply p_lv supplies the precharge circuit 100, and may also supply the control system 11. The driving terminal DR is connected to a controlled terminal (e.g., GATE terminal of MOSFET) of the switch 104 outside the power manager 102, and outputs a driving signal to the controlled terminal of the switch. The compensation terminal COMP receives a compensation signal for providing compensation of the control loop (control loop). The ground end GND is grounded. The feedback terminal FB is also grounded, for example, by being connected to the ground terminal GND. The Enable terminal FA/SD is for receiving an Enable signal s_enable to activate or deactivate the precharge circuit 100. The Enable signal s_enable may be provided by a controller (not shown) external to the precharge circuit 100.
The switch 104 has a controlled terminal, a first connection terminal, and a second connection terminal. The controlled terminal is connected to the driving terminal DR of the power manager 102, and receives a driving signal to control on/off of the switch 104 under the control of the driving signal. The first connection terminal is connected to the transformer 114 and outputs a switching signal. The second connection terminal is grounded via a shunt resistor R1.
The setting of the shunt resistor R1 and the setting of the resistance thereof are significant, and are used for assisting in realizing the current loop inside the power manager 102. The current loop determines how much current the switch 104 is opened. Taking the voltage across this shunt resistor R1 as the sampled voltage, the power manager 102 can determine from this sampled voltage whether the present current has reached a given upper limit of the current loop. If so, the power manager 102 controls the switch 104 to open. If the current loop fails, the input current to the transformer 114 is not limited and may be damaged by power coupling.
The value of the shunt resistor R1 is related to the input power of the transformer 114 and the maximum peak current flowing through the switch 104. The maximum peak current refers to the maximum peak current on the branch from the switch 104 to the transformer 114. When switch 104 is closed, transformer 114 is charged through switch 104, and current flowing from switch 104 to transformer 114 is drawn up when switch 104 is closed and falls when switch 104 is opened.
The filter 106 has: an input terminal receiving a PWM signal (s_pwm), and an output terminal outputting an analog level signal. The filter 106 is implemented to include, for example, a resistor and a capacitor. The filter 106 converts the received PWM signal (e.g., pulse signal) into an analog level signal. In this way, the filter 106 may convert PWM signals of different duty cycles to analog level signals of different magnitudes, wherein the larger the duty cycle of the PWM signal, the larger the magnitude of the corresponding analog level signal. For example, a PWM signal of 20% duty ratio is converted into an analog level signal of 1V; the 50% duty cycle PWM signal is converted into an analog level signal of 2.5V; the PWM signal of 80% duty cycle is converted into an analog level signal of 4V. The PWM signal may be provided by a controller (not shown) external to the precharge circuit 100.
The voltage follower 108 has: an input coupled to the output of the filter 106 to receive the analog level signal; an output terminal for outputting the received analog level signal; and another input terminal connected to the output terminal. The voltage follower 108 is configured to output the analog level signal obtained after the filtering in a voltage follower manner.
The feedback compensator 110 has: an input connected to the output of the voltage follower 108 to receive an analog level signal; the other input end connected with the voltage dividing circuit 112 is used for receiving the voltage dividing signal; and an output terminal connected to the compensation terminal COMP of the power manager 102 to output a compensation signal to the compensation terminal COMP of the power manager 120.
The voltage divider 112 is coupled between the feedback compensator 110 and the transformer 114. The voltage dividing circuit 112 includes two voltage dividing resistor units, each of which may include one or more resistors, respectively. The connection point of the two voltage dividing resistor units is connected to the other input terminal of the feedback compensator 110 to provide the voltage dividing signal to the feedback compensator 110. The voltage dividing ratio may be predetermined so as to determine the equivalent resistance values of the two voltage dividing resistance units.
The transformer 114 includes: a primary winding W1, an auxiliary winding W2, and a secondary winding W3. The primary winding W1 and the auxiliary winding W2 are located on the low voltage SIDE (LV SIDE). The secondary winding W3 is located on the high voltage SIDE (HV SIDE). One end of the primary winding W1 is connected to the low-voltage power supply p_lv, and the other end is connected to a first connection terminal of the switch 104 for outputting a switching signal. The auxiliary winding W2 is connected in parallel with the voltage dividing circuit 112. The secondary winding W3 is connected in parallel with the dc bus capacitor 200 to precharge the dc bus capacitor 200.
The rectifier circuit 116 is connected in series to a branch of the secondary winding W3 of the transformer 114 connected to the dc bus capacitor 200. The rectifying circuit 116 includes two or more subunits connected in series in sequence. The withstand voltage capability of each sub-unit is equal, and each sub-unit includes a rectifying diode and an RC absorption circuit connected in parallel thereto.
The number of the rectifying circuit 116 including the sub-units may be determined according to the high voltage to be born, for example, two sub-units may be employed when a withstand voltage of 800V is required on the high voltage side, and four sub-units may be employed when a withstand voltage of 1600V is required. Regardless of the number of subunits employed, their respective pressure resistance is equal. For example, the device model and parameters are the same for each subunit. This design is advantageous because of the unequal withstand voltage, which may present a problem in that after one subunit is damaged, the other subunits are also damaged.
The passive load 118 is connected on the high voltage side of the transformer 114 and in parallel with the dc bus capacitor 200. The resistance of the passive load 118 is associated with the lowest charge voltage provided by the precharge circuit 100 to the dc bus capacitor 200. During the precharge of the dc bus capacitor 200 by the precharge circuit 100, the charge voltage provided to the dc bus capacitor 200 may be varied, for example, from small to large until a desired precharge voltage is reached.
The lowest charge voltage provided by the precharge circuit 100 to the dc bus capacitor 200 is associated with the input voltage of the primary winding W1 of the transformer 114 and the minimum duty cycle of the power manager 102.
In one embodiment, the resistance of the passive load 118 is associated with device parameters of a plurality of devices of the precharge circuit 100. For example, the resistance of the passive load 118 is determined by the following equation:
wherein R is load Is the resistance of the passive load 118;
L m is the inductance value of the primary winding W1 of the transformer 114;
V in is the voltage of the power supply p_lv;
η is the efficiency of the precharge circuit 100;
T on is the minimum enable on time T by the power manager 102 min (on) the determined minimum on-time of the switch 104;
f is the switching frequency of switch 104;
V o is the lowest charge voltage provided by the precharge circuit 100 to the dc bus capacitor 200.
In this embodiment, the switching frequency f may be associated with the resistance of the ground resistor R2 connected to the enable terminal FA/SD of the power manager 102.
In this embodiment, the efficiency η of the precharge circuit 100 is derived as follows: η= (input power-loss power)/input power. The input power is the power received by the low voltage power supply. The lost power is caused by various losses of the precharge circuit 100, such as switching tube loss, transmission line loss, transformer copper loss, iron loss, and leakage inductance loss.
It will be appreciated that the efficiency η of the precharge circuit 100, which is a value estimated in advance for determining the resistance value of the passive load 118, may be updated as the precharge circuit 100 is used. The resistance value of the passive load 118 may be further optimized by this updated actual value.
Setting the passive load and determining the resistance of the passive load is significant because the power manager 102 has a minimum enable on-time T min (on), i.e., the minimum on time of the power manager 102 in response to the Enable signal s_enable, results in the minimum duty cycle of the switch 104 not being implemented as 0, which may be a value greater than 0. Thus, there is inevitably a minimum output voltage at the output of the precharge circuit 100. Each switching operation transfers energy to the dc bus capacitor 200. In this case, if a passive load is not provided, such a problem may occur: the desired minimum precharge voltage is 450V (i.e., the minimum charge voltage desired to be provided to dc bus capacitor 200 is 450V), but the charge voltage corresponding to the minimum enable on time of power manager 102 has reached 600V, such that the desired minimum precharge voltage of 450V cannot be achieved. Setting a passive load and determining an appropriate resistance value for the passive load may solve such a problem.
The high frequency wave capacitor 120 is disposed on the high voltage side of the transformer 114 and is connected in parallel with the dc bus capacitor 200. The high frequency wave capacitor 120 may include one or more capacitors connected in series, for example, a ceramic capacitor having good high frequency characteristics is selected.
It should be noted that in an embodiment of the present invention, the precharge circuit 100 is implemented as a flyback circuit for converting a low voltage to a high voltage, wherein the transformer 114 has not only the function of electrical isolation and voltage matching, but also the function of storing energy, exciting and charging by a fast chopper and pulse-type switching current, and discharging energy out on the secondary side (i.e., high voltage side) by a rectifying circuit.
It should be noted that in embodiments of the present invention, the power manager 102 may be implemented using a power management IC, such as a LM3478 model power management IC. However, in the present invention, the connection method of the pins of the power management IC is different from the conventional connection method. This difference is mainly reflected in the fact that the feedback terminal FB of the power manager 102 is connected to ground, rather than to a feedback circuit as is commonly done in connection with maintaining a stable output. According to the usual connection mode of the power management IC, only a flyback circuit with a fixed output can be realized, but according to the embodiment of the present invention, the feedback terminal FB is grounded, so that the regulator inside the power manager is saturated, and at the same time, an external regulator is designed (i.e., the COMP pin is connected to an external regulator built by an op amp). Moreover, by receiving PWM signals (S_PWM) with different duty ratios, analog level signals with different magnitudes are obtained after filtering.
While the foregoing describes some embodiments, these embodiments are given by way of example only and are not intended to limit the scope of the invention. The appended claims and their equivalents are intended to cover all modifications, substitutions and changes made within the scope and spirit of this application.

Claims (10)

1. A precharge circuit for precharging a dc bus capacitor, comprising:
a power manager having: the power input end is connected with the low-voltage power supply to receive input power, the driving end outputs a driving signal, the compensation end receives a compensation signal and the feedback end is grounded;
a switch is provided with: a controlled end for receiving the driving signal, a first connection end for outputting a switching signal, and a second connection end grounded via a shunt resistor;
a filter includes: an input end for receiving a PWM signal and an output end for outputting an analog level signal;
a voltage follower has: an input end for receiving the analog level signal, an output end for outputting the analog level signal, and another input end connected with the output end;
a feedback compensator includes: an input terminal for receiving the analog level signal, another input terminal for receiving a divided voltage signal, and an output terminal for outputting the compensation signal to a compensation terminal of the power manager; and
a transformer having a primary winding on a low voltage side and a secondary winding on a high voltage side, the primary winding being coupled between the low voltage power supply and a first connection of the switch, the secondary winding being coupled between the other input of the compensator and ground, the secondary winding being coupled with the dc bus capacitor to precharge the dc bus capacitor.
2. The precharge circuit of claim 1 wherein said precharge circuit further comprises: a passive load connected in parallel with the DC bus capacitor at the high voltage side of the transformer, and
wherein the resistance of the passive load is associated with a minimum charging voltage provided by the precharge circuit to the dc bus capacitor, and the minimum charging voltage is associated with an input voltage of the primary winding and a minimum duty cycle of the power manager.
3. The precharge circuit of claim 2 wherein the resistance of the passive load is determined by the formula:
wherein L is m Is the inductance value of the primary winding of the transformer;
V in is the voltage of the low voltage power supply;
η is the efficiency of the precharge circuit;
T on is a minimum on-time of the switch associated with a minimum enabled on-time of the power manager;
f is the switching frequency of the switch;
V o is the lowest charging voltage provided by the precharge circuit to the dc bus capacitor.
4. A precharge circuit as claimed in claim 2 or 3 wherein the efficiency η of the precharge circuit varies with the use of the precharge circuit and the resistance value of the passive load varies based on the variation in the efficiency η.
5. The precharge circuit of any of claims 1-4 wherein the precharge circuit further comprises:
a rectifying circuit connected in series to one output branch of the secondary winding, the rectifying circuit comprising two or more subunits connected in series in turn,
wherein the withstand voltage capability of each subunit is equal, and each subunit comprises a rectifier diode and an RC absorption circuit connected in parallel with the rectifier diode.
6. The precharge circuit of any of claims 1-5 wherein the precharge circuit further comprises:
and the voltage dividing circuit is coupled between the feedback compensator and the auxiliary winding and is provided with two voltage dividing resistor units, and the connection point of the two voltage dividing resistor units is connected with the other input end of the compensator so as to provide the voltage dividing signal for the compensator.
7. The precharge circuit of any of claims 1-6 wherein the precharge circuit further comprises:
a high frequency wave capacitor connected in parallel with the dc bus capacitor on the high voltage side of the transformer, having two or more capacitors connected in series.
8. The precharge circuit of any of claims 1-7 wherein a resistance value of the shunt resistor is associated with the input power and a maximum spike current flowing through the switch.
9. A dc voltage converter comprising:
a power system including a dc bus capacitor; and
a control system coupled to the power system, comprising a precharge circuit according to any one of claims 1-7 for controlling the precharge circuit to precharge the dc bus capacitor.
10. A fuel cell system comprising:
a fuel cell stack;
a high voltage battery;
the dc voltage converter of claim 9, coupled between the fuel cell stack and the high voltage battery, comprising a dc bus capacitor; and
a contactor coupled between the fuel cell stack and the dc voltage converter or between the dc voltage converter and the high voltage battery, the contactor configured to be opened at the beginning of the switching of the dc voltage converter into the fuel cell system and to be closed after the pre-charging of the dc bus capacitor is completed.
CN202210817440.0A 2022-07-12 2022-07-12 Pre-charging circuit, direct-current voltage converter and fuel cell system comprising same Pending CN117439243A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202210817440.0A CN117439243A (en) 2022-07-12 2022-07-12 Pre-charging circuit, direct-current voltage converter and fuel cell system comprising same

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202210817440.0A CN117439243A (en) 2022-07-12 2022-07-12 Pre-charging circuit, direct-current voltage converter and fuel cell system comprising same

Publications (1)

Publication Number Publication Date
CN117439243A true CN117439243A (en) 2024-01-23

Family

ID=89552156

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202210817440.0A Pending CN117439243A (en) 2022-07-12 2022-07-12 Pre-charging circuit, direct-current voltage converter and fuel cell system comprising same

Country Status (1)

Country Link
CN (1) CN117439243A (en)

Similar Documents

Publication Publication Date Title
US11152852B2 (en) Bidirectional DC/DC converter and method for charging the intermediate circuit capacitor of a DC/DC converter from the low-voltage battery
US9478995B2 (en) Battery system
CN107650729B (en) The pre-charging device of the High-Voltage Electrical Appliances of new-energy automobile
CN110326183B (en) Charging device and vehicle-mounted power supply device
US10840814B2 (en) Power conversion system
CN110774909A (en) OBC circuit, OBC charger, new energy automobile and fill electric pile
KR101734210B1 (en) Bidirectional dc-dc converter
KR20220029522A (en) Single stage ac-dc converter
US11689112B2 (en) DC-DC converter and vehicle
CN112421961A (en) Vehicle-mounted DC/DC converter with reverse pre-charging function and vehicle-mounted charging device
US5717579A (en) Power supply unit, more specifically battery charger for electric vehicles and the like
KR20210018598A (en) Electric power conversion system and control method therefor
US11411505B2 (en) DC-DC converter with pre-charging of a first electrical network from a second electrical network
CN117411155A (en) Charging device, charging pile and charging system
CN117439243A (en) Pre-charging circuit, direct-current voltage converter and fuel cell system comprising same
CN107615634B (en) Power conversion device and power supply system using same
CN112572192B (en) Vehicle-mounted charging system and vehicle with same
CN110797877B (en) High-voltage generator bus voltage control method and high-voltage generator
CN210898931U (en) DC/DC circuit soft start control circuit and vehicle-mounted equipment
CN113346755A (en) Vehicle-mounted isolated bidirectional DCDC converter
KR20220094661A (en) DC-DC Converter Based on Current Sensing of Inductor
CN112224038B (en) Energy conversion device, power system and vehicle
CN116686182A (en) Bidirectional DC/DC converter, control method thereof and vehicle
US20230143719A1 (en) Vehicle Power Conversion System and Method
CN220785473U (en) Charging control system and vehicle

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication