CN211969175U - Pre-charging device for high-voltage bus capacitor of new energy automobile - Google Patents
Pre-charging device for high-voltage bus capacitor of new energy automobile Download PDFInfo
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- CN211969175U CN211969175U CN202020277956.7U CN202020277956U CN211969175U CN 211969175 U CN211969175 U CN 211969175U CN 202020277956 U CN202020277956 U CN 202020277956U CN 211969175 U CN211969175 U CN 211969175U
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- 239000003990 capacitor Substances 0.000 title claims abstract description 136
- 238000007600 charging Methods 0.000 title claims abstract description 89
- 238000002955 isolation Methods 0.000 claims abstract description 51
- 230000002457 bidirectional effect Effects 0.000 claims abstract description 37
- 238000006243 chemical reaction Methods 0.000 claims abstract description 37
- 239000000872 buffer Substances 0.000 claims abstract description 34
- 238000005070 sampling Methods 0.000 claims abstract description 11
- 238000004804 winding Methods 0.000 claims description 20
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- 239000007983 Tris buffer Substances 0.000 description 4
- 230000000903 blocking effect Effects 0.000 description 2
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- 238000004146 energy storage Methods 0.000 description 2
- 230000000630 rising effect Effects 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
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Abstract
A pre-charging device for a high-voltage bus capacitor of a new energy automobile comprises a bidirectional DC-DC conversion circuit, a capacitor voltage sampling circuit and a controller; the bidirectional DC-DC conversion circuit is coupled between the high-voltage bus capacitor and the charging power supply, and the output end of the capacitor voltage sampling circuit is coupled with the input end of the controller. The bidirectional DC-DC conversion circuit comprises an isolation transformer,A first rectifying/inverting circuit, a second rectifying/inverting circuit, and an inductor LfAnd a switching tube Q7And a switching tube Q8And a capacitor Cbuffer. The controller can control the bidirectional DC-DC conversion circuit to work in a pre-charging mode, the bidirectional DC-DC conversion circuit charges the high-voltage bus capacitor in a push-pull circuit mode in the pre-charging mode, and the bidirectional DC-DC conversion circuit charges the high-voltage bus capacitor in an isolation booster circuit mode after the voltage of the high-voltage bus capacitor reaches a preset threshold value. The utility model discloses simple structure, it is with low costs, safe and reliable.
Description
Technical Field
The utility model relates to a new energy automobile field especially relates to a pre-charging device of new energy automobile's high-voltage bus-bar capacitance.
Background
As shown in fig. 1, an electric System of an electric vehicle generally includes a high voltage Battery pack 91, a Battery Management System (BMS) 92, a terminal box 93, a high voltage electrical device 94, and the like, and when the vehicle is started, the Battery Management System 92 controls the terminal box 93 to connect the high voltage Battery pack 91 and the high voltage electrical device 94, and the high voltage Battery pack 91 charges the high voltage electrical device 94. The high voltage electrical device 94 may be any of a variety of high voltage electrical devices, such as a high voltage DC-DC converter, an inverter, a vehicle charger, and the like. These high-voltage consumers are connected in parallel to a high-voltage dc bus, whose dc input is usually provided with a high-voltage bus capacitor C1. One end of a high-voltage bus capacitor of all high-voltage electric equipment is connected with the anode of a direct-current bus of the electric automobile, and the other end of the high-voltage bus capacitor is connected with the cathode of the direct-current bus of the electric automobile. Because the voltage of the high-voltage bus capacitor cannot suddenly change, a pre-charging circuit for pre-charging the capacitor is needed to ensure the electricity utilization safety at the moment when the high-voltage circuit is switched on.
The traditional pre-charging circuit mainly comprises a pre-charging contactor 95 and a pre-charging resistor 96, and the pre-charging resistor 96 is used for limiting the impact current when the high-voltage battery is wrapped on the high-voltage bus capacitor, but the heat loss of the resistor and the contactor is caused, the energy of the battery is consumed, the endurance mileage of the electric vehicle is further reduced, and the potential risk of thermal failure of parts is caused. To overcome the above disadvantages, the applicant proposed a new precharge circuit structure in the patent application with application number 201711015137.4, application number 2017, 26/10/78, in which a switch tube Q is added to the basic topology of the bi-directional hvdc/dc converter8The branch formed by the capacitor and the branch formed by the low-voltage side output capacitor Co and the switching tube Q9 which are connected in series. The pre-charging circuit has low energy loss and light weight because the pre-charging contactor and the pre-charging resistor are not arrangedAnd high charging efficiency, but also has the following defects: 1. the basic topology is greatly changed, the cost is high, and the control complexity is increased, except for the switching tubes Q1-Q6 of the basic topology, the switching tubes Q7 and Q8 are alternately conducted in the first stage to carry out duty ratio control, and the switching is carried out to constant high and low level control in the second stage; the switching tube Q9 is controlled to be off in the first stage and to be on in the second stage, and the control and state switching of the three switching tubes are complex; correspondingly, the switching tube Q7 and the switching tube Q8 form a half-bridge upper tube and a half-bridge lower tube, and in the first pre-charging stage, a special half-bridge driving chip is needed to realize high-speed alternate conduction, so that the cost is high; 2. the switching tube Q8 is directly bridged at two ends of the output side, so that the risk of short circuit failure of the low-voltage side of the system is increased; 3. once the switch Q9 is opened, the main function of the converter is lost.
Disclosure of Invention
The technical problem to be solved by the utility model is to provide a pre-charging device with simple structure, low cost, safety and reliability.
In order to solve the technical problem, the utility model discloses the technical scheme who takes is:
a pre-charging device for a high-voltage bus capacitor of a new energy automobile is provided with a direct-current bus and a charging power supply, wherein one end of the high-voltage bus capacitor is connected with the positive electrode of the direct-current bus of the new energy automobile, and the other end of the high-voltage bus capacitor is connected with the negative electrode of the direct-current bus of the new energy automobile; the pre-charging device comprises a bidirectional DC-DC conversion circuit, a capacitor voltage sampling circuit and a controller; the bidirectional DC-DC conversion circuit is coupled between the high-voltage bus capacitor and the charging power supply, so that the charging power supply can charge the high-voltage bus capacitor through the bidirectional DC-DC conversion circuit; the output end of the capacitor voltage sampling circuit is coupled with the input end of the controller, and the capacitor voltage sampling circuit is used for collecting the voltage of the high-voltage bus capacitor; the bidirectional DC-DC conversion circuit is characterized by comprising an isolation transformer, a first rectifying/inverting circuit, a second rectifying/inverting circuit and an inductor LfAnd a switching tube Q7And a switching tube Q8And a capacitor Cbuffer(ii) a The first rectifying/inverting circuit is connected with the high-voltage bus capacitor in parallelThe primary side of the isolation transformer is connected with the first rectifying/inverting circuit, and the secondary side of the isolation transformer is connected with the second rectifying/inverting circuit; inductor LfOne end of the first rectifying/inverting circuit is connected with the second rectifying/inverting circuit, and the capacitor CbufferAnd a switching tube Q8One end of the formed series branch is connected with the inductor LfOne end of the first rectifying/inverting circuit is connected with a common junction of the second rectifying/inverting circuit, and a capacitor CbufferAnd a switching tube Q8The other end of the formed series branch circuit is connected with a second rectifying/inverting circuit; switch tube Q7Second conducting terminal and inductor LfIs connected with the other end of the switch tube Q7The first conducting end of the capacitor is connected with the anode of a charging power supply, and the cathode of the charging power supply is connected with a capacitor CbufferAnd a switching tube Q8The other end of the formed serial branch; the controller is respectively connected with the first rectifying/inverting circuit, the second rectifying/inverting circuit and the switching tube Q7Control terminal and switching tube Q8The control end of the controller is connected; the controller can control the bidirectional DC-DC conversion circuit to work in a pre-charging mode, the bidirectional DC-DC conversion circuit charges the high-voltage bus capacitor in a push-pull circuit mode in the pre-charging mode, and the bidirectional DC-DC conversion circuit charges the high-voltage bus capacitor in an isolation booster circuit mode after the voltage of the high-voltage bus capacitor reaches a preset threshold value until the voltage of the high-voltage bus capacitor reaches a preset charging voltage value.
Furthermore, the first rectification/inversion circuit consists of a full-bridge circuit, and the full-bridge circuit comprises a first bridge arm and a second bridge arm; the first bridge arm is connected with the high-voltage bus capacitor in parallel, and comprises switching tubes Q sequentially connected in series from top to bottom1And a switching tube Q3(ii) a The second bridge arm comprises switching tubes Q connected in series from top to bottom2And a switching tube Q4(ii) a Switch tube Q1And a switching tube Q3The common contact point of the transformer is connected with one end of a primary winding of the isolation transformer; the other end of the primary winding of the isolation transformer is connected with the switching tube Q2And a switching tube Q4A common junction of (1); the second rectifying/inverting circuit comprises a switching tube Q5And a switching tube Q6Switching tube Q6First conducting terminal of the isolating transformer and a secondary winding of the isolating transformerIs connected to one end of a switching tube Q5The first conducting end of the switch tube Q is connected with the other end of the secondary winding5Second conducting terminal and capacitor CbufferThe other end of the series branch composed of the switching tube Q8 is connected with the switching tube Q6The second conducting terminal of the capacitor is connected to the capacitor CbufferAnd a switching tube Q8The other end of the formed series branch circuit and a switch tube Q5The center tap of the secondary winding and the capacitor C are respectively connectedbufferOne end of a series branch consisting of the switching tube Q8 and an inductor LfOne end of the two ends are connected; the controller is respectively connected with the switch tube Q1Control terminal and switching tube Q2Control terminal and switching tube Q3Control terminal and switching tube Q4Control terminal and switching tube Q5Control terminal and switching tube Q6Is connected with the control end of the controller.
Further, the bidirectional DC-DC conversion circuit comprises a capacitor CoCapacitor CoOne end of which is connected to the switching tube Q7Second conducting terminal and inductor LfThe common contact of the other end of (1), a capacitor CoThe other ends of the two capacitors are respectively connected with a capacitor CbufferAnd a switching tube Q8The other end of the formed series branch circuit and the negative electrode of the charging power supply.
The utility model discloses at least, following technological effect has:
1. according to the utility model discloses a precharge device increases a set of electric capacity C through the low pressure side at the basic topological structure of current new energy automobile's high pressure DC-DC converterbufferThe switching tube Q8 and the basic topology of the DC-DC converter are combined and transformed; when the switching tube Q8 is switched on, the topology can be converted into a push-pull circuit (push-pull) by the isolation boost circuit (boost), the switching tube Q8 is switched off, and the topology returns to the isolation boost circuit from the push-pull circuit, so that the two-stage pre-charging function is realized; the first stage is converted into a push-pull circuit with 0V starting capability, a basic voltage is established on a high-voltage bus capacitor, and after the basic voltage is established, the second stage is switched into an isolation booster circuit to enable the high-voltage bus capacitor to be charged to a final target voltage, so that the problem of high-voltage side is solvedThe soft start problem is solved when the voltage is 0V, so that the generation of impact current during charging is avoided, and the safety and reliability of the charging process are improved;
2. according to the utility model discloses a precharge device of an embodiment changes little to the basic topological structure of high DC-DC converter, and circuit structure and control process are simpler, because the quantity of the switch tube that waits to control has reduced, and the state switches over and also reduces, so realize the process of precharging simpler; in addition, compared with the CN201711015137.4 solution, the embodiments of the present invention have the advantages that the control of the switching tube Q7 and the switching tube Q8 is simpler, a dedicated half-bridge driving chip is not needed, and although a capacitor is added, the cost is reduced because a half-bridge driving chip and a large current Mos tube (the switching tube Q8 in the CN201711015137 solution) are reduced;
3. according to an embodiment of the present invention, the pre-charging device does not use the switch tube Q8The low-voltage side short-circuit failure prevention device is arranged at two ends of the output side, so that the risk of short-circuit failure of the low-voltage side of the system is reduced, and the reliability is improved.
Drawings
Fig. 1 shows a schematic block diagram of an electrical system of a conventional electric vehicle.
Fig. 2 shows a schematic block diagram of an embodiment of the pre-charging device of the present invention.
Fig. 3 shows a schematic circuit diagram of an embodiment of the pre-charging device of the present invention.
Fig. 4 shows a circuit topology of a non-isolated boost circuit.
Fig. 5 shows the circuit topology of a high voltage isolated boost circuit.
Fig. 6 shows an operation timing diagram of the switching tube of the pre-charging device in the push-pull circuit mode according to an embodiment of the present invention.
Fig. 7 shows a timing diagram of the operation of the switch tube of the pre-charging device in the isolated boost circuit mode according to an embodiment of the present invention.
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.
Please refer to fig. 2. According to the utility model discloses a precharge device of new energy automobile's high-voltage bus electric capacity, including electric capacity voltage sampling circuit 2, two-way DC-DC converting circuit 3 and controller 5.
The capacitor voltage sampling circuit 2 is used for collecting the high-voltage bus capacitor CinThe output end of the capacitor voltage sampling circuit 2 is coupled with the input end of the controller 5 so as to collect the high-voltage bus capacitor CinIs sent to the controller 5. High-voltage bus capacitor CinOne end of the positive electrode is connected with the positive electrode of the direct current bus of the new energy automobile, and the other end of the positive electrode is connected with the negative electrode of the direct current bus of the new energy automobile.
The bidirectional DC-DC conversion circuit 3 is coupled to the high-voltage bus capacitor CinAnd a charging power supply VLV_batSo that the charging power supply VLV_batThe bidirectional DC-DC conversion circuit can be used for converting the DC voltage into a high-voltage bus capacitor CinAnd (6) charging. The bidirectional DC-DC conversion circuit 3 includes an isolation transformer TrA first rectifying/inverting circuit 31, a second rectifying/inverting circuit 32, an inductor LfAnd a switching tube Q7、Switch tube Q8And a capacitor Cbuffer。
First rectifying/inverting circuit 31 and high-voltage bus capacitor CinParallel connected, isolating transformer TrIs connected to the first rectifying/inverting circuit 31, isolating the transformer TrIs connected to the second rectifying/inverting circuit 32. Inductor LfIs connected to the second rectifying/inverting circuit 32, and a capacitor CbufferOne end of which is connected to the inductor LfAnd a common connection point of the second rectifying/inverting circuit 32, a capacitor CbufferThe other end of the switch tube Q is connected with8First conducting terminal of (1), switching tube Q8Is connected to the second rectifying/inverting circuit 32; switch tube Q7Second conducting terminal and inductor LfIs connected with the other end of the switch tube Q7The first conducting terminal and the charging power supply VLV_batIs connected with the positive pole of the charging power supply VLV_batNegative electrode of (2) and switching tube Q8Is connected to the second conducting terminal. In other embodiments, electricity may also be usedContainer CbufferIs arranged on the switching tube Q8At this time, the switching tube Q8The first conducting terminal is connected to the inductor LfOne end of the first rectifying/inverting circuit is connected with a common contact of the second rectifying/inverting circuit, and a switching tube Q8Second conducting terminal and capacitor CbufferIs connected to a capacitor CbufferThe other end of the first rectifying/inverting circuit is connected with a second rectifying/inverting circuit; charging power supply VLV_batNegative electrode of (1) and capacitor CbufferAnd the other end of the two are connected. Switch tube Q8NMOS tube or PMOS tube can be adopted, and the grid, drain and source of the NMOS tube form a switch tube Q8The control end, the first conducting end and the second conducting end of the PMOS tube, and the grid electrode, the source electrode and the drain electrode of the PMOS tube form a switch tube Q8The control terminal, the first conducting terminal and the second conducting terminal.
The controller 5 is respectively connected with the first rectifying/inverting circuit 31, the second rectifying/inverting circuit 32 and the switching tube Q7Control terminal and switching tube Q8Is connected with the control end of the controller. The controller 5 can control the bidirectional DC-DC conversion circuit 3 to work in a pre-charging mode, and in the pre-charging mode, the bidirectional DC-DC conversion circuit 3 firstly performs a function of charging the high-voltage bus capacitor C in a Push-pull (Push-pull) circuit modeinCharging, and enabling the bidirectional DC-DC conversion circuit to charge the high-voltage bus capacitor C in the isolation booster circuit mode after the voltage of the high-voltage bus capacitor reaches a preset threshold valueinCharging is carried out until the high-voltage bus capacitor CinReaches a preset charging voltage value.
Further, the bidirectional DC-DC conversion circuit 3 includes a capacitor CoCapacitor CoOne end of which is connected to the switching tube Q7Second conducting terminal and inductor LfThe common contact of the other end of (1), a capacitor CoThe other ends of the two are respectively connected with a switch tube Q8Second conducting terminal and charging power supply VLV_batThe negative electrode of (1).
The first rectifying/inverting circuit 31 and the second rectifying/inverting circuit 32 may each be composed of a push-pull circuit, a full bridge circuit, or a half bridge circuit. R in the figureLDRepresenting the load.
In the present embodiment, as shown in fig. 3, the first rectifying/inverting circuit 31 is composed of a full bridge circuit. The full bridge circuit comprisesA first bridge arm and a second bridge arm; first bridge arm and high-voltage bus capacitor CinConnected in parallel, the first bridge arm comprises switching tubes Q connected in series from top to bottom1And a switching tube Q3(ii) a The second bridge arm comprises switching tubes Q connected in series from top to bottom2And a switching tube Q4. Switch tube Q1And a switching tube Q3The common contact point of the transformer is connected with one end of a primary winding of the isolation transformer; the other end of the primary winding of the isolation transformer is connected with the switching tube Q2And a switching tube Q4The common junction of (1).
The second rectifying/inverting circuit 32 includes a switching tube Q5And a switching tube Q6Switching tube Q6The first conducting end of the switch tube Q is connected with one end of a secondary winding of the isolation transformer5The first conducting end of the switch tube Q is connected with the other end of the secondary winding5Second conducting terminal of and the switch tube Q8Is connected with the second conducting end of the switch tube Q6The second conducting end of the switch is connected with the switching tube Q5Second conducting terminal of and the switch tube Q8The center tap of the secondary winding and the capacitor C are respectively connectedbufferOne terminal of (1) and an inductance LfAre connected at one end.
The controller 5 is respectively connected with the switch tube Q1Control terminal and switching tube Q2Control terminal and switching tube Q3Control terminal and switching tube Q4Control terminal and switching tube Q5Control terminal and switching tube Q6Is connected with the control end of the controller.
Further, the full bridge circuit includes a resonant inductor LrA first clamping diode Dc1And a second clamping diode Dc2. Resonant inductor LrOne end of which is connected to the switching tube Q1And a switching tube Q3Common contact of (3), resonant inductor LrAnd the other end of the isolating transformer TrIs connected to one end of the primary winding. First clamping diode Dc1Respectively with the switching tube Q1First conducting terminal of and switching tube Q2Is connected to the first conducting terminal of the first clamping diode Dc1Respectively with the resonant inductor LrAnother end and isolation ofTransformer TrIs connected to one end of the primary winding. Second clamping diode Dc2And the first clamping diode Dc1Is connected to the anode of a second clamping diode Dc2Respectively with the positive pole of the switching tube Q3Second conducting terminal of and the switching tube Q4Is connected to the second conducting terminal.
Optionally, the full bridge circuit comprises a dc blocking capacitor CbDc blocking capacitor CbConnected in series to the switching tube Q2And a switching tube Q4Common contact and isolation transformer TrBetween the other end of the primary winding.
Optionally, the switch tube Q1And a switching tube Q2And a switching tube Q3And a switching tube Q4And a switching tube Q5And a switching tube Q6And a switching tube Q7And a switching tube Q8The NMOS transistors are all NMOS transistors, the grid electrode of each NMOS transistor is a control end, the drain electrode of each NMOS transistor is a first conduction end, and the source electrode of each NMOS transistor is a second conduction end.
The controller 5 is used for controlling the switching tube Q when the bidirectional DC-DC conversion circuit 3 is in a push-pull circuit mode7And a switching tube Q8Normally-on, control isolation transformer TrAnd a switching tube Q1To the switching tube Q6Forming a push-pull circuit; when the bidirectional DC-DC conversion circuit 3 is in the isolation booster circuit mode, the controller 5 controls the switching tube Q7Normally-on, control switch tube Q8Normally off and control the inductance LfIsolation transformer TrAnd a switching tube Q1To the switching tube Q6Forming an isolation booster circuit.
Specifically, the bidirectional DC-DC conversion circuit 3 is a pair of high-voltage bus capacitors CinThe pre-charging is divided into two stages, the first stage is a push-pull circuit mode stage, and in the first stage, the switch tube Q7And a switching tube Q8Simultaneously turning on and charging power supply VLV_bat(in this embodiment, a low-voltage battery) current passes through the capacitor CoInductor LfAnd a capacitor CbufferP-type filter circuits formed so that the capacitor CbufferUpper gain and charging source VLV_batA consistent stable input voltage. This isThe voltage passes through an isolation transformer TrAnd a switching tube Q1To the switching tube Q6The push-pull circuit is formed by controlling the switching tube Q5And a switching tube Q6On duty ratio of the high voltage side to the high voltage bus capacitance CinAnd charging is carried out. When high voltage bus capacitor CinWhen the voltage of the high-voltage battery V is charged to a predetermined threshold valueHV_batThe base voltage necessary for the boost topology has been obtained. The first stage can adopt open-loop control or closed-loop control, and the method is to obtain the high-voltage bus capacitor CinThe voltage signal on the inductor is controlled in voltage mode or the high-voltage side resonant inductor L is takenrThe average current above is used as a feedback signal to perform current mode control on it. The second phase is a conventional isolated boost circuit mode phase. At the end of the first phase, the switching tube Q8Open, inductance LfIsolation transformer TrAnd a switching tube Q1To the switching tube Q6Forming an isolation booster circuit. Switch tube Q5And a switching tube Q6Inverting the boosted voltage to AC power and sending to isolation transformer TrSecondary side of (2) via an isolation transformer TrTransforming in an isolating transformer TrThe primary side of the transformer obtains alternating current with higher voltage, and the alternating current passes through a switching tube Q1To the switching tube Q4High voltage bus capacitor C for rectificationinAnd charging until the voltage reaches the final target voltage. The second stage can obtain the high-voltage bus capacitor CinThe voltage signal on the inductor is controlled in voltage mode or the high-voltage side resonant inductor L is takenrThe average current of the voltage step up is used as a feedback signal for current mode control.
As shown in fig. 4, in the conventional non-isolated boost circuit (generally used in low voltage system), there is no 0V start-up problem because the input voltage Vin is initially charged to the capacitor Co on the output side through the transistor Dh of the upper tube Qh (as shown in fig. 4). In the high voltage isolation boost circuit shown in fig. 5, the isolation transformer T is usedrAt the beginning, the voltage of the capacitor Co is 0V, and Vo = (Vin × N1/N2)/(1-D), N according to the formula of the output voltage (Vo) of the high-voltage isolation boost circuit1 is an isolation transformer TrN2 is an isolation transformer TrEven if the number of turns of the secondary side coil is small, a voltage slightly larger than Vin × N1/N2 is generated on the output side, namely, voltage is suddenly superposed on a 0V capacitor, so that large current impact is caused, the charging current is uncontrollable, and a switching tube is burned out in serious cases. Therefore, in the application of isolating the boost circuit, it is very important to establish the boost base voltage of Vin × N1/N2 at the high voltage side.
According to the method, the circuit topology is converted into a push-pull circuit architecture in the first stage by adding an additional branch circuit in the basic topology of the bidirectional DC-DC conversion circuit, the output voltage of the push-pull circuit conforms to a formula Vo = (Vin × N1/N2) × D, wherein D is a duty ratio, and when D is gradually increased from 0 to 1, Vo is gradually increased from 0V to Vin × N1/N2, so that the problem of direct large voltage and capacitance and current impact do not exist, and the problem of 0V soft start is solved. After the boost base voltage of Vin × N1/N2 is established on the high-voltage side, the second-stage circuit topology is restored to the conventional boost circuit until the target voltage is charged.
Referring to fig. 6 and 7, in fig. 6 and 7, t represents time, and Ts is the switching period of the switching tube. As shown in fig. 6, when the bidirectional DC-DC converter circuit 3 is in the push-pull mode (i.e., the first stage in the pre-charge mode), the switching tube Q7And a switching tube Q8Is always in a conducting state, and the switching tube Q1To the switching tube Q4The working frequency is 100KHz, and the switch tube Q is controlled5And a switching tube Q6The output is charged with constant current, and the duty ratio of the switching tube Q5 and the switching tube Q6 is gradually increased from 1% to 49%. High-voltage bus capacitor CinThe voltage on the charging circuit is charged to the base voltage (i.e. Vin × N1/N2, where Vin refers to the charging source VLV_batVoltage) to the second phase of precharging. In the second stage, as shown in FIG. 7, the switch tube Q8Cut off, switch tube Q7When the switch tube Q5 is closed, the voltage is boosted by controlling the ratio of the overlapping area of the driving signals of the switch tube Q6, and the overlapping area of the driving signals of the switch tube Q5 and the switch tube Q6 is equivalent to the inductance LfIn the energy storage stage, the non-overlapping region is equivalent to the inductance LfAccording to the boost circuit principle, the larger the energy storage time ratio is, the higher the output voltage is. In order to realize the synchronous rectification of the high-voltage side, the control sequence of the high-voltage side switching tubes Q1-Q4 is as follows: switch tube Q1Rising edge follow switch tube Q5Driving rising edge of (1), switching tube Q4Falling edge follow switch tube Q5Driving the falling edge of the switching tube Q3Rising edge follow switch tube Q6Driving rising edge of (1), switching tube Q2Follows Q along the falling edge6Driving the falling edge. The control loop can be a current loop, a voltage loop or a high-voltage bus capacitor CinThe charging current is stabilized at a preset target current value to finish charging.
According to the utility model discloses a precharge device of new energy automobile's high-voltage bus electric capacity still can work in forward step-down (Buck) mode and reverse step-up (boost) mode.
In the forward voltage reduction mode, a high-voltage side input power supply VHV_batOutput voltage of the switching tube Q1~ Q4Is inverted into AC power and sent to an isolation transformer TrPrimary side of (2) via an isolation transformer TrIn an isolating transformer TrThe secondary side of the transformer obtains alternating current with lower voltage, and the alternating current passes through a switching tube Q5And Q6After being rectified, the current passes through an inductor LfAnd a capacitor CoThe low voltage side of the filter (2) is used for obtaining a direct current with lower voltage (for example, 12V).
In reverse boost mode, the charging source VLV_batAnd auxiliary power supply is carried out to the high-voltage side. Inductor LfAnd a switching tube Q5And a switching tube Q6Form a boost circuit for the low-voltage side power supply VLV_batStep up and isolate transformer TrAnd a switching tube Q1To the switching tube Q6Forming a push-pull circuit. Switch tube Q5And Q6Inverting the boosted voltage to AC power and sending to isolation transformer TrSecondary side of (2) via an isolation transformer TrIn an isolating transformer TrThe primary side of the transformer obtains a relatively high voltageAC power, AC power passing through switch tube Q1~ Q4Is rectified and then passes through a high-voltage bus capacitor CinFiltering to obtain direct current with higher voltage at the high-voltage side.
According to the utility model discloses a precharge device can realize through the series branch road that increases a set of electric capacity and switch tube at the low pressure side of the basic topological structure of current new energy automobile's high pressure DC-DC converter, and when switch tube Q8 switched on, the topology could be transformed into push-pull circuit (push-pull) by keeping apart boost circuit (boost) (can understand, when switch tube Q8 switched on, the low voltage power input was followed electric capacity C from the switch tube Q8 and is realizedoJump to the capacitance CbufferLet the inductance LfThe power supply is temporarily lost, so that the topology is equivalently provided with one less inductor, the conversion to push-pull is realized), the switching tube Q8 is disconnected, and the topology returns to the isolation booster circuit from the push-pull circuit, so that the two-stage pre-charging function is realized; the first stage is converted into a push-pull circuit with 0V starting capability, a basic voltage is established on a high-voltage bus capacitor, and after the basic voltage is established, the second stage is switched into an isolation booster circuit to enable the high-voltage bus capacitor to be charged to a final target voltage, so that the soft starting problem when the high-voltage side is 0V is solved, and the generation of impact current during charging is avoided. Compared with the prior art, the utility model discloses a pre-charging device's circuit structure and control process are simpler, and the charging process safe and reliable.
Claims (10)
1. The pre-charging device for the high-voltage bus capacitor of the new energy automobile comprises a direct-current bus and a charging power supply, wherein one end of the high-voltage bus capacitor is connected with the positive electrode of the direct-current bus of the new energy automobile, and the other end of the high-voltage bus capacitor is connected with the negative electrode of the direct-current bus of the new energy automobile; the pre-charging device comprises a bidirectional DC-DC conversion circuit, a capacitor voltage sampling circuit and a controller; the bidirectional DC-DC conversion circuit is coupled between the high-voltage bus capacitor and the charging power supply, so that the charging power supply can charge the high-voltage bus capacitor through the bidirectional DC-DC conversion circuit; the output end of the capacitor voltage sampling circuit and the controllerThe input end of the controller is coupled, and the capacitor voltage sampling circuit is used for collecting the voltage of the high-voltage bus capacitor; the bidirectional DC-DC conversion circuit is characterized by comprising an isolation transformer, a first rectifying/inverting circuit, a second rectifying/inverting circuit and an inductor LfAnd a switching tube Q7And a switching tube Q8And a capacitor Cbuffer；
The first rectifying/inverting circuit is connected with the high-voltage bus capacitor in parallel, the primary side of the isolation transformer is connected with the first rectifying/inverting circuit, and the secondary side of the isolation transformer is connected with the second rectifying/inverting circuit; inductor LfOne end of the first rectifying/inverting circuit is connected with the second rectifying/inverting circuit, and the capacitor CbufferAnd a switching tube Q8One end of the formed series branch is connected with the inductor LfOne end of the first rectifying/inverting circuit is connected with a common junction of the second rectifying/inverting circuit, and a capacitor CbufferAnd a switching tube Q8The other end of the formed series branch circuit is connected with a second rectifying/inverting circuit; switch tube Q7Second conducting terminal and inductor LfIs connected with the other end of the switch tube Q7The first conducting end of the capacitor is connected with the positive electrode of the charging power supply, and the negative electrode of the charging power supply is connected with the capacitor CbufferAnd a switching tube Q8The other end of the formed serial branch;
the controller is respectively connected with the first rectifying/inverting circuit, the second rectifying/inverting circuit and the switching tube Q7Control terminal and switching tube Q8The control end of the controller is connected; the controller can control the bidirectional DC-DC conversion circuit to work in a pre-charging mode, the bidirectional DC-DC conversion circuit charges the high-voltage bus capacitor in a push-pull circuit mode in the pre-charging mode, and the bidirectional DC-DC conversion circuit charges the high-voltage bus capacitor in an isolation booster circuit mode after the voltage of the high-voltage bus capacitor reaches a preset threshold value until the voltage of the high-voltage bus capacitor reaches a preset charging voltage value.
2. The pre-charging device of the high-voltage bus capacitor of the new energy automobile according to claim 1, wherein the first rectifying/inverting circuit and the second rectifying/inverting circuit are each composed of a push-pull circuit, a full-bridge circuit or a half-bridge circuit.
3. The pre-charging device for the high-voltage bus capacitor of the new energy automobile according to claim 2, wherein the first rectifying/inverting circuit is composed of a full-bridge circuit, and the full-bridge circuit comprises a first bridge arm and a second bridge arm; the first bridge arm is connected with the high-voltage bus capacitor in parallel, and comprises switching tubes Q sequentially connected in series from top to bottom1And a switching tube Q3(ii) a The second bridge arm comprises switching tubes Q sequentially connected in series from top to bottom2And a switching tube Q4(ii) a Switch tube Q1And a switching tube Q3The common contact point of the transformer is connected with one end of a primary winding of the isolation transformer; the other end of the primary winding of the isolation transformer is connected to the switching tube Q2And a switching tube Q4A common junction of (1);
the second rectifying/inverting circuit comprises a switching tube Q5And a switching tube Q6Switching tube Q6The first conducting end of the switch tube Q is connected with one end of a secondary winding of the isolation transformer5The first conducting end of the switch tube Q is connected with the other end of the secondary winding5Second conducting terminal and capacitor CbufferThe other end of the series branch composed of the switching tube Q8 is connected with the switching tube Q6The second conducting terminal of the capacitor is connected to the capacitor CbufferAnd a switching tube Q8The other end of the formed series branch circuit and a switch tube Q5The center tap of the secondary winding is respectively connected with the capacitor CbufferOne end of a series branch consisting of the switching tube Q8 and an inductor LfOne end of the two ends are connected;
the controllers are respectively connected with the switching tubes Q1Control terminal and switching tube Q2Control terminal and switching tube Q3Control terminal and switching tube Q4Control terminal and switching tube Q5Control terminal and switching tube Q6Is connected with the control end of the controller.
4. The pre-charging device for the high-voltage bus capacitor of the new energy automobile according to claim 3, wherein the full-bridge circuit comprises a resonant inductor, a first clamping diode and a second clamping diode;
one end of the resonance inductor is connected to the switching tube Q1And a switching tube Q3The other end of the resonant inductor is connected with one end of a primary winding of the isolation transformer;
the negative electrode of the first clamping diode is respectively connected with the switching tube Q1First conducting terminal of and switching tube Q2The first conducting end of the first clamping diode is connected, and the anode of the first clamping diode is respectively connected with the other end of the resonant inductor and one end of the primary winding of the isolation transformer; the negative pole of the second clamping diode is connected with the positive pole of the first clamping diode, and the positive poles of the second clamping diodes are respectively connected with the switching tube Q3Second conducting terminal of and the switching tube Q4Is connected to the second conducting terminal.
5. The pre-charging device for the high-voltage bus capacitor of the new energy automobile according to claim 3, wherein the switching tube Q is1And a switching tube Q2And a switching tube Q3And a switching tube Q4And a switching tube Q5And a switching tube Q6And a switching tube Q7The NMOS transistor is characterized in that the NMOS transistor is an NMOS transistor, a grid electrode of the NMOS transistor is a control end, a drain electrode of the NMOS transistor is a first conduction end, and a source electrode of the NMOS transistor is a second conduction end.
6. The pre-charging device for the high-voltage bus capacitor of the new energy automobile according to any one of claims 3 to 5, wherein the controller is configured to control a switch tube Q when the bidirectional DC-DC conversion circuit is in the push-pull circuit mode7And a switching tube Q8Normally on, controlling the isolation transformer and the switch tube Q1To the switching tube Q6Forming a push-pull circuit;
the controller is used for controlling the switching tube Q when the bidirectional DC-DC conversion circuit is in the isolation booster circuit mode7Normally on and controlSwitch tube Q8Normally off and control the inductance LfIsolation transformer and switching tube Q1To the switching tube Q6Forming an isolation booster circuit.
7. The pre-charging device for the high-voltage bus capacitor of the new energy automobile according to claim 6, wherein the controller is configured to control the bidirectional DC-DC conversion circuit to perform constant-current charging on the high-voltage bus capacitor in a push-pull circuit mode in the pre-charging mode.
8. The pre-charging device for the high-voltage bus capacitor of the new energy automobile according to claim 1, wherein the bidirectional DC-DC conversion circuit comprises a capacitor CoCapacitor CoOne end of which is connected to the switching tube Q7Second conducting terminal and inductor LfThe common contact of the other end of (1), a capacitor CoThe other ends of the two capacitors are respectively connected with a capacitor CbufferAnd a switching tube Q8The other end of the formed series branch circuit and the negative electrode of the charging power supply.
9. The pre-charging device for the high-voltage bus capacitor of the new energy automobile according to claim 1, wherein the capacitor C isbufferOne end of which is connected to the inductor LfOne end of the first rectifying/inverting circuit is connected with a common junction of the second rectifying/inverting circuit, and a capacitor CbufferThe other end of the switch tube Q is connected with8First conducting terminal of (1), switching tube Q8The second conducting end of the first rectifying/inverting circuit is connected with the first rectifying/inverting circuit; negative pole and switching tube Q of charging source8The second conducting end of the first conducting terminal is connected with the second conducting end of the second conducting terminal;
or, the switch tube Q8The first conducting terminal is connected to the inductor LfOne end of the first rectifying/inverting circuit is connected with a common contact of the second rectifying/inverting circuit, and a switching tube Q8Second conducting terminal and capacitor CbufferIs connected to a capacitor CbufferThe other end of the first rectifying/inverting circuit is connected with a second rectifying/inverting circuit; the negative pole of the charging power supply and the capacitor CbufferAnd the other end of the two are connected.
10. The pre-charging device for the high-voltage bus capacitor of the new energy automobile according to claim 1 or 9, wherein the switching tube Q is8The NMOS transistor or PMOS transistor, the gate, drain and source of the NMOS transistor constitute a switch transistor Q8The control end, the first conducting end and the second conducting end of the PMOS tube, and the grid electrode, the source electrode and the drain electrode of the PMOS tube form a switch tube Q8The control terminal, the first conducting terminal and the second conducting terminal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202020277956.7U CN211969175U (en) | 2020-03-09 | 2020-03-09 | Pre-charging device for high-voltage bus capacitor of new energy automobile |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202020277956.7U CN211969175U (en) | 2020-03-09 | 2020-03-09 | Pre-charging device for high-voltage bus capacitor of new energy automobile |
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| Publication Number | Publication Date |
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| CN211969175U true CN211969175U (en) | 2020-11-20 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202020277956.7U Withdrawn - After Issue CN211969175U (en) | 2020-03-09 | 2020-03-09 | Pre-charging device for high-voltage bus capacitor of new energy automobile |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111251893A (en) * | 2020-03-09 | 2020-06-09 | 科博达技术股份有限公司 | Pre-charging device for high-voltage bus capacitor of new energy automobile |
| CN113489119A (en) * | 2021-07-05 | 2021-10-08 | 杭州蔚斯博系统科技有限公司 | Power converter with pre-charging function and working process thereof |
-
2020
- 2020-03-09 CN CN202020277956.7U patent/CN211969175U/en not_active Withdrawn - After Issue
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111251893A (en) * | 2020-03-09 | 2020-06-09 | 科博达技术股份有限公司 | Pre-charging device for high-voltage bus capacitor of new energy automobile |
| CN111251893B (en) * | 2020-03-09 | 2024-05-14 | 科博达技术股份有限公司 | Pre-charging device for high-voltage bus capacitor of new energy automobile |
| CN113489119A (en) * | 2021-07-05 | 2021-10-08 | 杭州蔚斯博系统科技有限公司 | Power converter with pre-charging function and working process thereof |
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