CN-117767719-B - Vehicle-mounted DC-DC conversion device and electric automobile

CN117767719BCN 117767719 BCN117767719 BCN 117767719BCN-117767719-B

Abstract

The invention provides a vehicle-mounted DC-DC conversion device and an electric automobile, and relates to the field of power sources, wherein the vehicle-mounted DC-DC converter comprises a first bridge unit, a transformer, a synchronous rectification unit and a clamping absorption circuit; the controller is used for outputting driving signals for driving the first bridge unit, the synchronous rectification unit and the switching tube in the clamping absorption circuit, and sequentially works in a discharging stage of the clamping capacitor, a pre-charging stage of the clamping capacitor and a closed-loop starting stage with transformer magnetic saturation protection in a starting stage of the vehicle-mounted DC-DC converter in a forward mode for converting a first voltage into a second voltage. The reliability of starting the vehicle-mounted DC-DC converter can be improved.

Inventors

BI QINGSHENG
LI ZHAO
HAO SHIQIANG

Assignees

浙江富特科技股份有限公司

Dates

Publication Date: 20260508
Application Date: 20231226

Claims (8)

1. A vehicle-mounted DC-DC conversion device, comprising: The vehicle-mounted DC-DC converter comprises a first bridge unit, a second bridge unit and a first voltage generation unit, wherein the first bridge unit is used for receiving or outputting a first voltage; the secondary winding center tap transformer, the first bridge unit connects the primary winding; the synchronous rectification unit is characterized in that a first synchronous rectification tube and a second synchronous rectification tube are respectively connected between two ends of a secondary winding and a grounding end, an inductor is connected between a center tap and a first end of a second capacitor, the second end of the second capacitor is grounded, and the second capacitor is used for outputting or receiving a second voltage; A controller for controlling the vehicle DC-DC converter to sequentially operate in a discharging stage of the clamping capacitor, a pre-charging stage of the clamping capacitor and a closed-loop starting stage with transformer magnetic saturation protection during a starting stage of the vehicle DC-DC converter in a forward mode of converting a first voltage into a second voltage, wherein In a discharging stage of the clamping capacitor, a driving signal output by the controller controls a switching tube in the first bridge unit to be not operated, and the first clamping switching tube and the second clamping switching tube operate in an amplifying region to discharge a voltage on the clamping capacitor to the second capacitor; In a pre-charging stage of the clamping capacitor, a driving signal output by a controller controls a switching tube in a first bridge unit to work, and the first clamping switching tube and the second clamping switching tube work to convert the first voltage into a voltage for charging the clamping capacitor; In the closed loop starting stage with the transformer magnetic saturation protection, the controller executes S1, namely, calculating the duty ratio D of a driving signal for driving a switching tube in the first bridge unit according to the input voltage of the vehicle-mounted DC-DC converter, the turn ratio of the transformer and the output voltage, S2, wherein the controller outputs the driving signal with the duty ratio D/2 to drive the switching tube in the first bridge unit to work, and after (2 n-1) driving pulses, the controller outputs the driving signal with the duty ratio D to drive the switching tube in the first bridge unit to work, wherein n is a natural number larger than or equal to 1.
2. The on-vehicle DC-DC conversion device according to claim 1, wherein the driving signal output from the controller controls to alternately turn on the first clamp switching tube and the second clamp switching tube in a discharging stage of the clamp capacitor.
3. The on-vehicle DC-DC conversion device according to claim 2, wherein the driving signal outputted by the controller to control the first clamp switching tube and the second clamp switching tube is a cluster of narrow pulses having a phase shift angle of 180 ° in a discharge phase of the clamp capacitor.
4. The on-vehicle DC-DC conversion apparatus according to claim 1, wherein the controller outputs a driving signal of a fixed duty ratio to the switching tube in the first bridge unit in a precharge phase of the clamp capacitor.
5. The on-vehicle DC-DC conversion apparatus according to claim 4, wherein in the precharge phase of the clamp capacitor, the clamp switching tube operating in the clamp snubber circuit is turned on after the switching tube operating in the first bridge unit is turned on, and the switching tube operating in the first bridge unit is turned off before the switching tube operating in the first bridge unit is turned off.
6. The vehicle-mounted DC-DC conversion device according to claim 5, wherein the controller performs: s1, the controller outputs a driving signal with a fixed duty ratio of one period to a switching tube working in the first bridge unit, and counts up 1; S2, judging whether the count value is smaller than the count set maximum value, if yes, entering a step S3, and if not, entering a step S4; s3, judging whether the voltage on the clamping capacitor is larger than a voltage set value, if so, entering a step S5, and if not, entering a step S1; s4, reporting a pre-charging failure, and ending a start-up stage of the vehicle-mounted DC-DC converter; s5, entering a closed loop start-up stage with transformer magnetic saturation protection of the vehicle-mounted DC-DC converter.
7. The vehicle-mounted DC-DC converter according to claim 1 or 6, wherein the vehicle-mounted DC-DC converter operates in a closed-loop mode during a closed-loop start-up phase with transformer magnetic saturation protection.
8. An electric vehicle comprising the on-vehicle DC-DC converter according to claim 1.

Description

Vehicle-mounted DC-DC conversion device and electric automobile Technical Field The invention relates to the field of power sources, in particular to a vehicle-mounted DC-DC conversion device and an electric automobile. Background With the development of science and technology and society, new energy automobiles have been widely used and have an increasing duty ratio. Electric vehicles often include a high voltage battery that draws electrical energy from a power grid and stores the energy in the high voltage battery as a source of electrical energy within the electric vehicle. An onboard DC-DC converter is used to convert high voltage battery energy of an electric vehicle to low voltage battery energy of, for example, 12V to power loads in a new energy vehicle. The conventional vehicle-mounted DC-DC converter is a bidirectional DC-DC converter, which can convert a high voltage (e.g., 400V) on a high-voltage battery into a low voltage (e.g., 12V) on a low-voltage battery, or convert a low voltage (e.g., 12V) on a low-voltage battery into a high voltage (e.g., 400V) on a high-voltage battery. When the vehicle-mounted DC-DC converter is started, the vehicle-mounted DC-DC converter may be required to work at a start-up state for converting a high voltage (such as 400V) on a high-voltage battery into a low voltage (such as 12V) on a low-voltage battery, which is called as a forward start-up state. It is also possible to start the machine, which requires the vehicle-mounted DC-DC converter to operate to convert a low voltage (e.g. 12V) on the low voltage battery to a high voltage (e.g. 400V) on the high voltage battery, we call the reverse start machine. The forward start and the reverse start can cause interference such as impact current, impact voltage and the like, and also can cause the problems that part of devices cannot work normally, such as switching tube loss, drive chip damage, transformer magnetic saturation and the like, so that the reliability of the vehicle-mounted DC-DC converter is influenced. Disclosure of Invention The invention provides a vehicle-mounted DC-DC conversion device, which comprises: The vehicle-mounted DC-DC converter comprises a vehicle-mounted DC-DC converter and a clamping absorption circuit, wherein the vehicle-mounted DC-DC converter comprises a vehicle-mounted DC-DC converter and a secondary winding center tap transformer, the vehicle-mounted DC-DC converter comprises a first bridge unit, a synchronous rectifying unit and a second synchronous rectifying unit, the first bridge unit is used for receiving or outputting a first voltage, the first bridge unit is connected with a primary winding, the first synchronous rectifying unit and the second synchronous rectifying unit are respectively connected between two ends of the secondary winding and a grounding end, an inductor is connected between the center tap and a first end of a second capacitor, the second end of the second capacitor is grounded, the second capacitor is used for outputting or receiving a second voltage, and the first clamping switching tube and the second clamping switching tube are respectively connected between two ends of the secondary winding and a first end of a clamping capacitor, and the second end of the capacitor is grounded; The device comprises a first secondary winding, a second secondary winding, a first secondary winding, a second secondary winding controller, a synchronous rectification unit, a switching tube in a clamp absorption circuit, a closed loop starting stage and a closed loop starting stage, wherein the first secondary winding is used for outputting driving signals for driving the first bridge unit, the synchronous rectification unit and the switching tube in the clamp absorption circuit, and the vehicle-mounted DC-DC converter is used for working in a forward mode of converting a first voltage into a second voltage. Further, in a discharging stage of the clamping capacitor, the driving signal output by the controller controls the switching tube in the first bridge unit to be not operated, and the first clamping switching tube and the second clamping switching tube operate to discharge the voltage on the clamping capacitor to the second capacitor. Further, in a discharging stage of the clamping capacitor, the driving signal output by the controller controls the first clamping switching tube and the second clamping switching tube to work in an amplifying region. Further, in a discharging stage of the clamping capacitor, the driving signal output by the controller controls the first clamping switching tube and the second clamping switching tube to be alternately conducted. Further, in the discharging stage of the clamping capacitor, the driving signals output by the controller to control the first clamping switching tube and the second clamping switching tube are a cluster of narrow pulses with a phase shift angle of 180 degrees. Further, the duration of the high level of one pulse peri