New energy vehicle high voltage grade charging compatible adaptation system and control method

Abstract

The invention provides a new energy vehicle high voltage grade charging compatible adaptation system and a control method, when a vehicle is connected to a charging pile supporting high voltage (800V) charging, a relay of a DC-DC module is closed, and the charging pile outputs current to directly charge a battery; when the vehicle is connected to a charging pile which does not support high-voltage charging, a relay in the DC-DC module is disconnected, and the boosting module works to boost the output voltage of the charging pile to the voltage required by the vehicle to charge a battery; braking is conducted in the running process of the vehicle, and high-voltage electricity of the kinetic energy recovery system charges the super capacitor after being subjected to voltage reduction through the DC-DC module; when the vehicle needs kinetic energy release for acceleration, low-voltage electricity output by the super capacitor is boosted through the DC-DC module and then is provided for the motor controller. The DC-DC module has various buck-boost functions, and can be matched with a kinetic energy recovery system and a super capacitor module to realize various working modes such as boost charging, constant-voltage charging, kinetic energy recovery and kinetic energy release.

Description

Technical Field

[0001] The present invention belongs to the technical field of new energy vehicle circuit design, and specifically relates to a high-voltage level charging compatible adaptation system and a control method for new energy vehicles. Background Art

[0002] In recent years, with the increase in battery capacity of new energy vehicles, consumers have an increasingly urgent need to increase charging power and shorten charging time. Increasing charging voltage is a typical method to increase charging power. Without changing the charging current, the charging power can be doubled by simply increasing the charging voltage from 400V to 800V. However, due to the large share of low-voltage charging piles on the market, in order to meet consumers' demand for charging at charging piles with different voltage specifications, it is necessary to develop a boost DCDC to increase the charging voltage to the voltage level required by the vehicle.

[0003] Kinetic energy recovery / release is one of the basic functions of new energy vehicles. Fully recovering braking energy during vehicle driving can increase the driving range. However, frequent short-term high-power energy recovery of the battery will reduce the battery life, and the maximum discharge capacity of the battery also restricts the instantaneous acceleration performance of the vehicle. Therefore, on-board supercapacitors, as a medium for kinetic energy recovery / release, are expected to be widely used in the future. However, the disadvantage of supercapacitors is that the voltage is low and cannot be the same as that of lithium batteries. The typical module operating voltage is about 200V. Therefore, the boost DCDC can be used as a transformer for supercapacitors. When kinetic energy is recovered, the 800V voltage is reduced to 200V to charge the supercapacitor. When kinetic energy is released, the 200V capacitor voltage is increased to 800V to provide additional energy for the motor.

[0004] At present, the 800V boost DCDC in the industry generally adopts the multiplexing motor controller inverter circuit and motor coil solution: 1) This solution uses the power switch tube in the motor controller as the switching element in the boost DCDC topology, and uses the magnetic induction coil in the motor as the energy storage inductor in the boost DCDC topology. 2) The boost DCDC of this solution is only used to increase the output voltage of the charging pile to the charging voltage required by the battery during DC charging, and has no other functions. 3) Since there is no compatible supercapacitor, the vehicle uses the power battery as the energy storage medium during energy recovery.

[0005] The above solution has the following disadvantages: 1) The boost DCDC can only be used when the motor is not working, and other functions cannot be expanded. If supercapacitors need to be adapted, high-power bidirectional DCDC needs to be developed separately, which will bring higher R&D costs and usage costs; 2) Since the boost DCDC reuses the motor controller inverter circuit and motor coil, it is not possible to optimize parameters for the boost DCDC working conditions when selecting components, which has a negative impact on factors such as system efficiency. 3) Using power batteries as energy recovery media and frequent short-term high-power charging have a negative impact on the life of the power batteries. 4) Due to the inability to adapt supercapacitors, the vehicle cannot obtain additional power output when accelerating. Summary of the invention

[0006] In response to the above problems, the present invention provides a high-voltage charging compatible adaptation system and control method for new energy vehicles, which can simultaneously support 400V / 800V bidirectional conversion and 200V / 800V bidirectional conversion: when the vehicle is connected to a charging pile that supports 800V, the internal relay of the DC-DC module is closed, and the output current of the charging pile directly charges the battery; when the vehicle is connected to a charging pile that does not support 800V, the internal relay of the DC-DC module is disconnected, and the boost module works to increase the output voltage of the charging pile to the voltage required by the vehicle to charge the battery; when the vehicle is braking during driving, the high voltage electricity of the kinetic energy recovery system is stepped down by the DC-DC module to charge the supercapacitor; when the vehicle needs to release kinetic energy to accelerate, the low voltage electricity output by the supercapacitor is stepped up by the DC-DC module and provided to the motor controller. The purpose of the present invention is achieved through the following technical solutions:

[0007] The present invention first provides a high-voltage charging compatible adaptation system for new energy vehicles, which includes a high-voltage battery system, a multi-purpose DC-DC module and an electric drive system. The high-voltage battery system includes a high-voltage battery pack (such as an 800V high-voltage battery pack), a supercapacitor and a battery management system. The DC-DC module is provided with a bidirectional DC-DC converter, and the DC-DC module is connected to a DC charging socket. The high-voltage battery system is connected to a motor controller and a DC-DC module through a high-voltage bus. Preferably, the DC-DC module of the charging compatible system is an independent part and does not share a circuit module with other controllers in the vehicle.

[0008] Furthermore, the DC-DC module has a first relay and a second relay for controlling the circuit state thereof.

[0009] Furthermore, the DC-DC module is provided with a filter circuit, a bidirectional DC-DC converter and a discharge circuit.

[0010] Furthermore, the bidirectional DC-DC converter adopts a dual half-bridge topology, which has a first capacitor C1, an inductor L, a first switch tube S1, a second switch tube S2, a first diode D1, a second diode D2 and a second capacitor C2. With this bidirectional DC-DC converter, when a new energy vehicle with an 800V high-voltage battery pack is connected to a 400V charging pile for boost charging or kinetic energy release, the bidirectional converter becomes a Boost converter, raising the voltage to 800V and delivering it to the high-voltage bus. When kinetic energy recovery or simulating the low-voltage battery pack voltage is performed, the bidirectional converter can be transformed into a Buck converter to reduce the high-voltage bus voltage.

[0011] Furthermore, the high-voltage battery system is provided with a battery main negative relay and a battery main positive relay for controlling the circuit state of the battery pack, and a capacitor main positive relay and a capacitor main negative relay for controlling the state of the supercapacitor.

[0012] The present invention further provides a control method for a high-voltage level charging compatible adaptation system for new energy vehicles. In the charging mode, when the charging pile can meet the charging demand of the high-voltage battery pack, charging is directly performed. When the charging pile cannot meet the charging demand of the high-voltage battery pack, the DC-DC module is used to increase the input voltage to high voltage and then charge the battery pack.

[0013] Specifically, in the charging mode of the charging compatible system, the charging method includes the following process:

[0014] Step S110: Detect the charging compatible system to ensure that all relays in the system are in the disconnected state. Specifically, in the charging mode, one side of the multi-purpose boost DC-DC module is connected to the DC charging pile through the DC charging socket. Before charging, the system detects and ensures that all relays are in the disconnected state and the power switch tube inside the boost DC-DC is in the disconnected state.

[0015] Step S120: Establish communication with the charging pile to determine whether the output voltage of the charging pile meets the charging requirements of the high-voltage battery pack. If the determination result is no, jump to step S130; if the determination result is yes, jump to step S150;

[0016] Step S130: Close the battery main positive relay and the battery main negative relay to put the bidirectional DC-DC converter into reverse buck mode, and output a voltage value not higher than the maximum output voltage of the charging pile to the DC charging socket to simulate the battery voltage; the system supports reverse output. During the charging process between the charging pile and the vehicle, the DC-DC module needs to simulate the output of 400V voltage at the output end for charging pile identification to ensure that the charging pile determines that the battery voltage is lower than its own maximum output voltage so that charging can proceed normally.

[0017] Step S140: receiving a charging pile signal, and when confirming that the charging pile enters the charging mode, controlling the bidirectional DC-DC converter to enter the BOOST mode, and increasing the input voltage to the high voltage required by the battery pack;

[0018] Step S150: Control the first relay and the second relay of the DC-DC module to close, so as to complete the charging of the high-voltage battery pack.

[0019] Furthermore, in the kinetic energy recovery mode, the bidirectional DC-DC converter converts the high voltage electricity of the electric drive system into the 200V low voltage electricity required by the supercapacitor to charge the capacitor.

[0020] Furthermore, in the kinetic energy release mode, the bidirectional DC-DC converter converts the low voltage electricity of the supercapacitor into high voltage electricity to power the electric drive system.

[0021] Preferably, the charging compatible system is provided with an over-temperature protection device, which reduces the charging and discharging power of the system when it detects that the internal temperature is greater than a first temperature threshold, and blocks the charging and discharging function of the system when it detects that the internal temperature is higher than a second temperature threshold.

[0022] The charging compatible system of the present invention can reach a maximum power of 500kW in a mode where no boosting is required for charging, which can meet the demand for high-power charging. In a mode where boosting and lowering are required, the maximum power of the system is 50kW and 120kW, meeting different cost requirements. The dynamic response time of the system is no more than 10ms, and the working efficiency is greater than 95% at rated power.

[0023] The beneficial effects of the present invention are:

[0024] (1) The DC-DC module of the present invention has multiple voltage-boosting and voltage-reducing functions and can be used in conjunction with a kinetic energy recovery system and a supercapacitor module to achieve multiple operating modes such as boost charging / constant voltage charging / kinetic energy recovery / kinetic energy release.

[0025] (2) Compared with the conventional boost DC-DC multiplexing of the motor controller inverter circuit and the motor coil, the present invention can optimize parameters for the boost DCDC working condition during component selection, thereby achieving a more ideal system operating efficiency.

[0026] (3) The present invention supports the use of supercapacitors as a kinetic energy recovery medium to avoid the negative impact of frequent short-term high-power charging on the life of the power battery. The service life of the vehicle's high-voltage battery can be greatly optimized.

[0027] (4) The present invention supports the use of supercapacitors as an energy source for kinetic energy release. Compared with vehicles with a single battery, it has a stronger power output and users can experience better acceleration. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Shown is a schematic diagram of a charging compatible system of the present invention;

[0029] Figure 2 Shown Figure 1 The topological structure diagram of the bidirectional DC-DC converter of the DC-DC module;

[0030] Figure 3 Shown is a schematic diagram of the charging compatible system of the present invention in charging mode;

[0031] Figure 4 Shown is a schematic diagram of the working process of the charging compatible system of the present invention in the charging mode;

[0032] Figure 5 Shown is a schematic diagram of the charging compatible system of the present invention in kinetic energy recovery / release mode. DETAILED DESCRIPTION

[0033] The technical scheme of the preferred embodiment of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] Embodiment 1:

[0035] This embodiment first provides a high-voltage charging compatible adaptation system for new energy vehicles, which includes a high-voltage battery system M1, a multi-purpose DC-DC module M2 and an electric drive system M3. Figure 2 As shown, the electric drive system M3 includes a motor controller U31 and a motor U32, the high-voltage battery system includes an 800V high-voltage battery pack U11, a supercapacitor U12 and a battery management system U13, the DC-DC module M2 is provided with a bidirectional DC-DC converter, the DC-DC module is connected to the DC charging socket, and the high-voltage battery system M1 is connected to the motor controller U31 and the DC-DC module M2 of the electric drive system M3 through a high-voltage bus. The DC-DC module is provided with a first relay J1 and a second relay J2 to control its circuit state.

[0036] In the illustrated embodiment, the filter circuit, the bidirectional DC-DC converter and the discharge circuit in the DC-DC module are as follows: Figure 2As shown, the bidirectional DC-DC converter adopts a dual half-bridge topology, which has a first capacitor C1, an inductor L, a first switch tube S1, a second switch tube S2, a first diode D1, a second diode D2 and a second capacitor C2. The working principle of this DC-DC module is: when connected to a 400V charging pile for boost charging or kinetic energy release, the bidirectional converter becomes a Boost converter, raising the voltage to 800V and delivering it to the high-voltage bus. When kinetic energy recovery or simulating the low-voltage battery pack voltage is performed, the bidirectional converter can be transformed into a Buck converter to reduce the high-voltage bus voltage.

[0037] In the illustrated embodiment, the high-voltage battery system M1 is provided with a battery main negative relay and a battery main positive relay for controlling the circuit state of the battery pack U11, and a capacitor main positive relay and a capacitor main negative relay for controlling the state of the supercapacitor U12.

[0038] Embodiment 2:

[0039] This embodiment provides a control method for a high-voltage charging compatible adaptation system for new energy vehicles, which can complete the functions of charging, kinetic energy recovery and release in the charging compatible adaptation system of embodiment 1. Specifically, 800V high-voltage battery packs, 400V or 800V charging piles, 200V supercapacitors, etc., which are widely used in current new energy vehicles, are used as examples for explanation:

[0040] In charging mode, if Figure 3 As shown in the figure, the system supports 800V constant voltage charging and 400V boost charging. After being connected to the charging pile, the system will identify the voltage level of the charging pile. If the charging pile supports 800V charging, the first relay J1 and the second relay J2 of the DC-DC module are closed to directly power the battery; if the charging pile does not support 800V charging, the relay of the DC-DC module is disconnected, and the voltage is increased to the battery requirement voltage through the DC-DC converter to charge the battery.

[0041] Specifically, in the charging mode of the charging compatible system, the charging method includes the following process: Figure 4 As shown:

[0042] Step S110: Detect the charging compatible system to ensure that all relays in the system are in the disconnected state. In the charging mode, one side of the multi-purpose DC-DC module is connected to the DC charging pile through the DC charging socket. Before charging, the system detects and ensures that all relays are in the disconnected state and the power switch tube inside the boost DC-DC is in the disconnected state.

[0043] Step S120: Establish communication with the charging pile to determine whether the output voltage of the charging pile meets the charging requirements of the high-voltage battery pack. If the determination result is no, jump to step S130 for boost charging. If the determination result is yes, directly jump to step S150 to enter the normal charging mode.

[0044] Step S130: Close the battery main positive relay and the battery main negative relay to put the bidirectional DC-DC converter into reverse buck mode, and output a voltage value not higher than the maximum output voltage of the charging pile to the DC charging socket at point A in the figure to simulate the battery voltage. Specifically, the system supports reverse output. During the charging process between the charging pile and the vehicle, the DC-DC module needs to simulate the output of 400V voltage at the output end for charging pile identification to ensure that the charging pile determines that the battery voltage is lower than its maximum output voltage so that charging can proceed normally.

[0045] Step S140: Receive the charging pile signal, and when it is confirmed that it has entered the charging mode, control the bidirectional DC-DC converter to enter the BOOST mode, and increase the input voltage to the high voltage required by the battery pack. After completing the charging pile identification, the charging pile enters the charging mode. During the charging process, the boost DC-DC module increases the input voltage to charge the high-voltage battery and ensures that the real-time power is not higher than its own rated power.

[0046] Step S150: Control the first relay and the second relay of the DC-DC module to close, so as to complete the charging of the high-voltage battery pack.

[0047] The system supports the recovery of vehicle kinetic energy to supercapacitors and the release of capacitor kinetic energy. In the kinetic energy recovery mode, the DCDC converts the 800V high voltage electricity of the electric drive system into the 200V low voltage electricity required by the supercapacitor to charge the capacitor. In the kinetic energy release mode, the DC-DC module converts the 200V low voltage electricity of the supercapacitor into 800V high voltage electricity to provide additional energy for the electric drive system. When the vehicle is driving, the first relay J1 and the second relay J2 should be disconnected, and the main positive and negative relays of the battery are closed. According to the control signal of the vehicle controller, the DC-DC adjusts its own working mode to kinetic energy recovery or kinetic energy release, converting the 800V voltage of the high-voltage bus into the 200V voltage required by the supercapacitor to charge it, or converting the 200V voltage of the supercapacitor into the 800V voltage of the high-voltage bus to power the motor controller of the electric drive system.

[0048] In the mode where boosting is not required for charging, the system's maximum power can reach 500kW, which can meet the needs of high-power charging. In the mode where boosting and lowering are required, the system's maximum power is 50kW and 120kW, meeting different cost requirements. The system's dynamic response time is no more than 10ms, and the working efficiency is greater than 95% at rated power.

[0049] In a preferred embodiment, the charging compatible system is provided with an over-temperature protection device, which reduces the charging and discharging power of the system when the internal temperature is detected to be greater than the first temperature threshold, and blocks the charging and discharging function of the system when the internal temperature is detected to be greater than the second temperature threshold. In a specific embodiment, the system uses liquid cooling for cooling and has a complete over-temperature protection mechanism. When the internal temperature is greater than 65°C (the first temperature threshold), the power is reduced, and when the temperature is greater than 75°C (the second temperature threshold), the system stops working completely.

[0050] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention. The dimensions described in the drawings and embodiments are not related to the specific objects and are not used to limit the protection scope of the present invention. The dimensions of the objects can be selected and changed according to actual needs.

Claims

1. A high-voltage charging compatible adaptation system for new energy vehicles, which includes a high-voltage battery system, a DC-DC module and an electric drive system. The high-voltage battery system includes a high-voltage battery pack, a supercapacitor and a battery management system. The DC-DC module is provided with a bidirectional DC-DC converter, and the DC-DC module is connected to a DC charging socket. The high-voltage battery system is connected to the motor controller and the DC-DC module of the electric drive system through a high-voltage bus.

2. According to claim 1, a new energy vehicle high voltage level charging compatible adaptation system is characterized in that: The DC-DC module has a first relay and a second relay which control the states thereof.

3. A high voltage level charging compatible adaptation system for new energy vehicles according to claim 2, characterized in that: The DC-DC module is provided with a filter circuit, a bidirectional DC-DC converter and a discharge circuit.

4. A high voltage charging compatible adaptation system for new energy vehicles according to claim 3, characterized in that: The bidirectional DC-DC converter adopts a dual half-bridge topology, and comprises a first capacitor C1, an inductor L, a first switch tube S1, a second switch tube S2, a first diode D1, a second diode D2 and a second capacitor C2.

5. A high voltage level charging compatible adaptation system for new energy vehicles according to any one of claims 1 to 4, characterized in that: The high-voltage battery system is provided with a battery main negative relay and a battery main positive relay for controlling the state of the battery pack circuit, and a capacitor main positive relay and a capacitor main negative relay for controlling the state of the supercapacitor.

6. A control method for a high voltage charging compatible adaptation system for new energy vehicles, characterized in that: In charging mode, when the output voltage of the charging pile can meet the charging demand of the high-voltage battery pack, charging is carried out directly. When the output voltage of the charging pile cannot meet the charging demand of the high-voltage battery pack, the battery pack is charged after the input voltage is increased to high voltage through the DC-DC module.

7. The control method of a high voltage level charging compatible adaptation system for new energy vehicles according to claim 6 is characterized in that: Charging methods include: Step S110: Detecting the charging compatible system to ensure that all relays in the system are in a disconnected state; Step S120: Establish communication with the charging pile to determine whether the output voltage of the charging pile meets the charging requirements of the high-voltage battery pack. If the determination result is no, jump to step S130; if the determination result is yes, jump to step S150; Step S130: close the battery main positive relay and the battery main negative relay, so that the bidirectional DC-DC converter enters the reverse buck mode, outputs a voltage value not higher than the maximum output voltage of the charging pile to the DC charging socket, and simulates the battery voltage; Step S140: receiving a charging pile signal, and when confirming that the charging pile enters the charging mode, controlling the bidirectional DC-DC converter to enter the BOOST mode, and increasing the input voltage to the high voltage required by the battery pack; Step S150: Control the first relay and the second relay of the DC-DC module to close, so as to complete the charging of the high-voltage battery pack.

8. The control method of a high voltage level charging compatible adaptation system for new energy vehicles according to claim 6 is characterized in that: In the kinetic energy recovery mode, the bidirectional DC-DC converter converts the high voltage electricity of the electric drive system into the 200V low voltage electricity required by the supercapacitor to charge the capacitor.

9. The control method of a high voltage level charging compatible adaptation system for new energy vehicles according to claim 6 is characterized in that: In the kinetic energy release mode, the bidirectional DC-DC converter converts the low voltage electricity of the supercapacitor into high voltage electricity to supply energy to the electric drive system.

10. A control method for a high voltage charging compatible adaptation system for new energy vehicles according to any one of claims 6 to 9, characterized in that: The charging compatible system is provided with an over-temperature protection device, which reduces the charging and discharging power of the system when it is detected that the internal temperature is greater than a first temperature threshold, and blocks the charging and discharging function of the system when it is detected that the internal temperature is higher than a second temperature threshold.

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