Power supply control circuit, power supply control system and electric vehicle

Abstract

The present invention provides a power supply control circuit, a power supply control system, and an electric vehicle. The power supply control circuit is applied to an electric drive system (EDS) supplied with a direct current voltage via a direct current power supply module. The power supply control circuit comprises: a control module, configured to perform control when a control condition for supplying an adjustable direct current voltage to an EDS is met, so that the adjustable direct current voltage is supplied to the EDS via the direct current power supply module. Thus, the voltage utilization rate and WLTC efficiency can be effectively improved.

Description

Power control circuits, power control systems, and electric vehicles Technical Field

[0001] This invention relates to the field of electric vehicle technology, and more particularly to power control circuits, power control systems, and electric vehicles. Background Technology

[0002] To ensure acceleration and maximum speed requirements, the peak torque and maximum speed of the drive motor are typically much higher than those required under common driving conditions, such as the Worldwide Harmonized Light Vehicles Test Cycle (WLTC), by more than double. This means that the DC voltage utilization (the ratio of motor terminal voltage to DC voltage) is very low under common operating conditions. The duty cycle of the pulse width modulated (PWM) voltage is very low, generating a large number of voltage harmonics, as well as the resulting current harmonics and iron losses. Ultimately, this results in the average efficiency of WLTC being far lower than the theoretical value assuming the electric drive system (EDS) is supplied by a sinusoidal current source.

[0003] As can be seen from the definition of voltage utilization, it can be improved in two ways: by increasing the motor's back electromotive force (EMF) and terminal voltage, and by reducing the DC voltage. As the voltage level and maximum speed increase, the voltage utilization of a WLTC decreases, which is very detrimental to WLTC efficiency.

[0004] Currently, efforts to improve WLTC efficiency primarily focus on material improvements, electromagnetic design, manufacturing processes, and control strategies. However, these methods offer limited improvements. Therefore, existing technologies are unlikely to substantially enhance WLTC efficiency. Summary of the Invention

[0005] In view of this, the present invention provides a power control circuit, a power control system, and an electric vehicle, thereby improving WLTC efficiency by increasing voltage utilization.

[0006] According to a first aspect of the present invention, a power control circuit is provided for an electric drive system (EDS) supplied with a DC voltage via a DC power module. The power control circuit includes a control module for controlling the supply of the adjustable DC voltage to the EDS via the DC power module, provided that control conditions for supplying an adjustable DC voltage to the EDS are met.

[0007] In one possible implementation, the control module is configured to: if the control condition is met, perform control to supply the adjustable DC voltage to the EDS via the DC power module while stepping down the DC voltage supplied by the DC power module, wherein the adjustable DC voltage is the DC voltage obtained after stepping down the DC voltage supplied by the DC power module.

[0008] In one possible implementation, if the control conditions are not met, the control module controls the supply of a constant DC voltage to the EDS via the DC power module, wherein the constant DC voltage is greater than the adjustable DC voltage.

[0009] In one possible implementation, the control module is configured to: if the control condition is not met, perform control to supply the constant DC voltage to the EDS via the DC power module without stepping down the DC voltage supplied by the DC power module, wherein the constant DC voltage is the DC voltage supplied by the DC power module.

[0010] In one possible implementation, the control module includes: a step-down processing unit for stepping down the DC voltage supplied by the DC power supply module; and a switching unit for connecting between the DC power supply module and the EDS when connected to the step-down processing unit if the control conditions are met, and connecting between the DC power supply module and the EDS when not connected to the step-down processing unit if the control conditions are not met.

[0011] In one possible implementation, the switching unit is a dual-channel switching switch or a single-contact switch.

[0012] In one possible implementation, the step-down processing unit includes a chopper circuit for stepping down the DC power supplied by the DC power module. The chopper circuit has a series circuit of a first switching element for step-down, an inductor, and a capacitor between the positive and negative terminals of the DC power module.

[0013] In one possible implementation, the chopper circuit further includes a circulating diode between the positive and negative terminals of the DC power module, the circulating diode being connected between the junction between the first switching element and the inductor and the negative terminal of the DC power module.

[0014] In one possible implementation, the chopper circuit further includes a second switching element between the positive and negative terminals of the DC power module, wherein the second switching element forms a half-bridge module with the first switching element, and the second switching element is connected between the connection point between the first switching element and the inductor and the negative terminal of the DC power module.

[0015] According to a second aspect of the present invention, a power control system is provided, comprising the aforementioned DC power module, power control circuit, and EDS, wherein the EDS includes an inverter and a motor.

[0016] According to a third aspect of the present invention, an electric vehicle is provided, comprising the power control system described above and a vehicle controller (VCU), configured to determine whether the control conditions are met based on the operating speed of the electric vehicle and the torque of the motor; if the control conditions are met, to determine the DC voltage to be adjusted based on the operating speed, the torque, and the DC voltage supplied by the DC power module, and to issue a command to the control module instructing the EDS to supply the determined DC voltage via the DC power module as the adjustable DC voltage.

[0017] According to the power control circuit, power control system, and electric vehicle of the present invention, compared to supplying a constant DC voltage to the EDS via a DC power module when control conditions for supplying an adjustable DC voltage to the EDS are met (e.g., the electric vehicle is in urban operating conditions), the present invention supplies an adjustable DC voltage (lower than the constant DC voltage) to the EDS via a DC power module when these control conditions are met. This effectively reduces the voltage supplied to the EDS (bus voltage), thereby improving not only voltage utilization but also the PWM duty cycle of the bus voltage, reducing PWM harmonic losses, and thus effectively improving WLTC efficiency. In this way, both voltage utilization and WLTC efficiency can be simultaneously achieved.

[0018] Other features and aspects of the invention will become clear from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0019] The accompanying drawings, which are included in and form part of this specification, illustrate exemplary embodiments, features, and aspects of the invention together with the specification and serve to explain the principles of the invention.

[0020] Figure 1 is a block diagram of a power control system according to this exemplary embodiment.

[0021] Figure 2 is a schematic diagram of a power control system according to this exemplary embodiment.

[0022] Figure 3 is a block diagram of a power control system according to this exemplary embodiment.

[0023] Figure 4 is a block diagram of a power control system according to this exemplary embodiment.

[0024] Figure 5 is a schematic diagram of a power control system according to this exemplary embodiment.

[0025] Figure 6 is a schematic diagram of a power control system according to this exemplary embodiment.

[0026] Figure 7 is a schematic diagram of a power control system in a first mode according to this exemplary embodiment.

[0027] Figure 8 is a schematic diagram of a power control system in a second mode according to this exemplary embodiment.

[0028] Figure 9 is a schematic diagram of a power control system according to this exemplary embodiment.

[0029] Figure 10 is a schematic diagram of a power control system in a second mode according to this exemplary embodiment.

[0030] Figure 11 is a schematic diagram of a power control system according to this exemplary embodiment.

[0031] Figure 12 is a schematic diagram of a power control system in a second mode according to this exemplary embodiment.

[0032] Figure 13 is a table of two power supply modes according to this exemplary embodiment.

[0033] Figure 14 is a schematic diagram of a typical implementation of an EDS using a first power supply mode and a second power supply mode according to this exemplary embodiment.

[0034] Figures 15 and 16 are tables showing the efficiencies of two sets of EDS or motor drive units measured when a constant DC voltage and an adjustable DC voltage are supplied to the EDS in the low-speed, low-torque region, respectively.

[0035] Figure 17 is a table showing the fundamental voltage required for operation in the low-speed, low-torque region according to this exemplary embodiment.

[0036] Figure 18 is a table showing the mechanical power required for operation in the low-speed, low-torque region according to this exemplary embodiment.

[0037] Figure 19 is a schematic diagram of another power control system according to this exemplary embodiment.

[0038] Figure 20 is a schematic diagram of another power control system in a second mode according to this exemplary embodiment.

[0039] Figure 21 is a table showing two power supply modes of another power control system according to this exemplary embodiment. Detailed Implementation

[0040] Various exemplary embodiments, features, and aspects of the present invention will now be described in detail with reference to the accompanying drawings. The same reference numerals in the drawings denote elements that have the same or similar functions. Although various aspects of the embodiments are shown in the drawings, they are not necessarily drawn to scale unless specifically indicated otherwise.

[0041] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments.

[0042] Furthermore, to better illustrate the present invention, numerous specific details are provided in the following detailed embodiments. Those skilled in the art should understand that the present invention can be practiced without certain specific details. In other instances, methods, means, elements, and circuits well known to those skilled in the art have not been described in detail in order to highlight the spirit of the invention.

[0043] As shown in Figure 1, the power control system of this exemplary embodiment may include a DC power module 100, a power control circuit 200, and an electric drive system EDS 300. The DC power module 100 is connected to the EDS 300 via the power control circuit 200. The power control circuit 200 controls the supply of a required DC voltage to the EDS 300 via the DC power module 100. This required DC voltage may be a constant DC voltage or an adjustable DC voltage. In one possible implementation, when a constant DC voltage needs to be supplied to the EDS 300, the power control circuit 200 controls the supply of the DC voltage from the DC power module 100 directly to the EDS 300. Conversely, when an adjustable DC voltage needs to be supplied to the EDS 300, the power control circuit 200 controls the supply of the DC voltage from the DC power module 100 to adjust the voltage and then supplies the adjusted DC voltage to the EDS 300.

[0044] In one possible implementation, the DC power module 100 may include a battery pack. When a constant DC voltage needs to be supplied to the EDS 300, the power control circuit 200 controls the DC power module 100 to use the battery pack to output a DC voltage to supply a constant DC voltage to the EDS 300. Correspondingly, when an adjustable DC voltage needs to be supplied to the EDS 300, the power control circuit 200 controls the DC power module 100 to step down the DC voltage output from the battery pack to the required DC voltage based on the operating speed of the electric vehicle and the torque of the electric vehicle's motor, and then supplies the required DC voltage to the EDS 300.

[0045] Therefore, under the control of the power control circuit 200, the DC power module 100 can supply different DC voltages to the EDS 300 in different power supply modes. These different power supply modes may include a first mode for supplying a constant DC voltage to the EDS 300 and a second mode for supplying an adjustable DC voltage to the EDS 300, wherein the constant DC voltage is greater than the adjustable DC voltage.

[0046] The EDS 300 is used to provide torque to the wheel assembly of an electric vehicle. For example, the EDS 300 may include an inverter and a motor. As shown in Figure 2, the EDS 300 includes an inverter 310 and a motor 320. The inverter 310 can provide three-phase current to the motor 320. The inverter 310 may include three bridge arms connected to the three-phase windings respectively. Each bridge arm may include an upper bridge arm and a lower bridge arm, and each of the upper and lower bridge arms includes a MOSFET and a diode connected in parallel. The motor 320 may be a synchronous motor used to drive the wheels in the electric vehicle. The motor 320 is a three-phase motor, which includes a stator and a rotor. The stator may include three-phase windings, which may include an A-phase winding, a B-phase winding, and a C-phase winding. One end of each of the three-phase windings is connected together to form a neutral point, and the other end of each is a free end, which is connected to the inverter 310. The operating principle of the inverter and the motor is similar to that of the prior art and will not be described in detail here.

[0047] It should be understood that electric vehicles operate under various conditions, with varying speeds and torques, and consequently, different power requirements. For example, the speed and torque of an electric vehicle in urban conditions are significantly lower than those in high-speed conditions. Consequently, the DC voltage required by the EDS 300 in urban conditions is lower than that required in high-speed conditions.

[0048] Therefore, in one possible implementation, the power control circuit 200 can selectively supply a corresponding DC voltage to the EDS 300 from the DC power module 100 based on the operating conditions of the electric vehicle. For example, the vehicle controller (VCU) of the electric vehicle can determine the power supply mode of the DC power module 100 based on the operating conditions of the electric vehicle and send a command to the power control circuit 200. The power control circuit 200, in response to receiving the command, performs control so that the DC power module 100 supplies DC voltage to the EDS 300 in that power supply mode. The power control circuit 200 will be described in detail below.

[0049] As shown in Figure 3, the power control circuit 200 may include a control module 210. The control module 210 can be used to control the supply of an adjustable DC voltage to the EDS 300 via the DC power module 100 when the control conditions for supplying an adjustable DC voltage to the EDS 300 are met.

[0050] In this embodiment, control conditions may include, for example, the operating speed of the electric vehicle being lower than a speed threshold and / or the torque of the electric vehicle's motor being lower than a torque threshold. It should be understood that this embodiment does not limit the specific content of the control conditions; any condition that indicates a need to supply an adjustable DC voltage to the EDS 300 can be used as a control condition in this embodiment.

[0051] For example, the control conditions may include, but are not limited to, at least one of the following conditions: the electric vehicle is operating in urban conditions; the electric vehicle requires low power (power below a threshold); the electric vehicle is operating at low speed and low torque (the electric vehicle's speed is below a speed threshold and the motor's torque is below a torque threshold); a command is received from the VCU carrying an indication that the control conditions are met; a command is received from the VCU carrying an indication to supply DC voltage to the EDS 300 in a second mode for supplying an adjustable DC voltage to the EDS 300, etc.

[0052] In this embodiment, when the control conditions are met, the control module 210 adjusts the DC voltage supplied by the DC power module 100 and supplies the adjusted DC voltage to the EDS 300 as the aforementioned adjustable DC voltage.

[0053] In one possible implementation, under the condition that the control conditions are met, the control module 210 can determine the DC voltage required by the EDS 300 based on the speed of the electric vehicle and the torque of the electric vehicle's motor, adjust the DC voltage supplied by the DC power module 100 to the required DC voltage, and supply the required DC voltage to the EDS 300.

[0054] Therefore, under the condition that the control conditions are met, the DC voltage supplied to the EDS 300 can be dynamically adjusted according to the speed of the electric vehicle and the torque of the motor, so that the DC voltage supplied to the EDS 300 can vary with the speed of the electric vehicle and the torque of the motor.

[0055] It should be noted that this embodiment does not limit the specific structure of the control module 210. Any circuit, module or device that can supply an adjustable DC voltage to the EDS 300 via the DC power module 100 when the control conditions are met can be used as the control module 210 of this embodiment.

[0056] For example, the control module 210 may include a switching module for switching the operating mode of supplying DC voltage to the EDS 300 (including the first mode and the second mode described above), and an adjustment module for adjusting the DC voltage supplied by the DC power module 100. In the first power supply mode, the switching module switches so that the adjustment module is not connected to the DC power module 100 and the EDS 300. Thus, the adjustment module does not adjust the DC voltage supplied by the DC power module 100, and the DC voltage supplied to the EDS 300 is the DC voltage supplied by the DC power module 100, i.e., the aforementioned constant DC voltage. In the second power supply mode, the switching module switches so that the adjustment module is connected to the DC power module 100 and the EDS 300. Thus, the adjustment module adjusts the DC voltage supplied by the DC power module 100, and the DC voltage supplied to the EDS 300 is the adjusted DC voltage, i.e., the aforementioned adjustable DC voltage.

[0057] According to this embodiment, compared to supplying a constant DC voltage to the EDS via a DC power module when the control conditions for supplying an adjustable DC voltage to the EDS are met (e.g., the electric vehicle is in urban conditions), this embodiment supplies an adjustable DC voltage to the EDS via a DC power module when the control conditions are met (the adjustable DC voltage is lower than the constant DC voltage). As a result, the voltage (bus voltage) supplied to the EDS can be continuously and effectively reduced, thereby significantly improving the voltage utilization rate in real time, especially the voltage utilization rate in the low-speed, low-power region, and significantly reducing PWM harmonic losses, thereby effectively improving WLTC efficiency and the driving range of the electric vehicle.

[0058] In addition, since the DC voltage supplied to the EDS 300 can be continuously adjusted in the low-speed, low-power region, the common-mode voltage, shaft voltage and its electro-corrosion risk, high-frequency loop current and EMC risk in the low-speed, low-power region can be effectively reduced.

[0059] In one possible implementation, the control module 210 is configured to: if the control condition is met, perform control to supply the adjustable DC voltage to the EDS 300 via the DC power module 100 while stepping down the DC voltage supplied by the DC power module 100, wherein the adjustable DC voltage is the DC voltage obtained after stepping down the DC voltage supplied by the DC power module 100.

[0060] For example, when the electric vehicle is in urban conditions, it means that an adjustable DC voltage, such as a lower DC voltage, needs to be supplied to the EDS 300. At this time, the control module 210 performs a step-down process on the DC voltage supplied by the DC power module 100 and supplies the step-down DC voltage to the EDS 300.

[0061] For example, when the electric vehicle is traveling at a low speed and the electric vehicle motor has low torque, it means that a lower DC voltage needs to be supplied to the EDS 300. At this time, the control module 210 performs a step-down process on the DC voltage supplied by the DC power module 100 and supplies the step-down DC voltage to the EDS 300.

[0062] In one possible implementation, the control module 210 is further configured to: in the event that the control conditions are not met, perform control to supply a constant DC voltage to the EDS 300 via the DC power module 100, wherein the constant DC voltage is greater than the adjustable DC voltage.

[0063] In one possible implementation, the control module 210 is configured to: if the control condition is not met, perform control to supply the constant DC voltage to the EDS 300 via the DC power module 100 without stepping down the DC voltage supplied by the DC power module 100, wherein the constant DC voltage is the DC voltage supplied by the DC power module 100.

[0064] For example, when the electric vehicle is operating at high speed, it indicates that a higher DC voltage needs to be supplied to the EDS 300. At this time, the control module 210 can directly supply the DC voltage supplied by the DC power module 100 to the EDS 300 without performing a step-down process on the DC voltage supplied by the DC power module 100.

[0065] For example, when the electric vehicle is traveling at a high speed and the electric vehicle motor has a high torque, it means that a higher DC voltage needs to be supplied to the EDS 300. In this case, the control module 210 can directly supply the DC voltage supplied by the DC power module 100 to the EDS 300 without performing a step-down process on the DC voltage supplied by the DC power module 100.

[0066] In one possible implementation, the control module 210 includes: a transformer processing unit 212 for stepping down the DC voltage supplied by the DC power module 100; and a switching unit 211 for connecting between the DC power module 100 and the EDS 300 when connected to the transformer processing unit 212 if the control conditions are met, and for connecting between the DC power module 100 and the EDS 300 when not connected to the transformer processing unit 212 if the control conditions are not met.

[0067] In this embodiment, as shown in FIG4, the DC power supply module 100 includes a component capable of supplying DC voltage U. dc Under controlled conditions, the switching unit 211 connects to the transformer processing unit 212, thus connecting the transformer processing unit 212 between the DC power module 100 and the EDS 300. This allows the DC voltage U to be processed via the transformer processing unit 212. dc A step-down process is performed to supply the stepped-down DC voltage to the EDS 300. Correspondingly, if the control conditions are not met, the switching unit 211 is not connected to the transformer processing unit 212. Thus, the transformer processing unit 212 is not connected between the DC power module 100 and the EDS 300, allowing the DC voltage U to be directly supplied to the EDS 300. dc Among them, the transformer processing unit 212 is, for example, a buck converter.

[0068] In one possible implementation, the switching unit 211 is a dual-channel switching switch S. As shown in Figure 5, when the switch S is connected to the first contact N1, the DC power supply module 100 is directly connected to the EDS 300 without going through the transformer processing unit 212, and the DC voltage U from the DC power supply module 100... dc The DC power supply module 100 is directly output to the EDS 300. When switch S is connected to the second contact N2, the DC power supply module 100 is connected to the EDS 300 via the transformer processing unit 212, which converts the DC voltage U from the DC power supply module 100 into a DC voltage U. dc Reduce the DC voltage to the required level and output that required DC voltage to the EDS 300.

[0069] In this embodiment, the transformer processing unit 212 includes a chopper circuit 2121. When control conditions are met, switch S is connected to the second contact N2, thereby connecting to the chopper circuit 2121 via the second contact N2. Conversely, when control conditions are not met, switch S is connected to the first contact N1, and not connected to the chopper circuit 2121 via the second contact N2. The chopper circuit 2121 is used to process the DC voltage U supplied by the DC power module 100. dc The voltage is stepped down. The chopper circuit 2121 has a series circuit of a switching element T1, an inductor L and a capacitor C for stepping down between the positive and negative terminals of the DC power module 100.

[0070] In one possible implementation, as shown in Figure 5, a switch S and a chopper circuit 2121 are inserted between the DC power supply module 100 and the EDS 300. The chopper circuit 2121 includes a switching element T1, an inductor L, and a capacitor C. The switching element T1 is a transistor, and this is one implementation of the first switching element.

[0071] In one possible implementation, as shown in Figure 6, the chopper circuit 2121 further includes a circulating diode D between the positive and negative terminals of the DC power module 100. The circulating diode D is connected between the connection point between the switching element T1 and the inductor L and the negative terminal of the DC power module 100. When the switch S is connected to the first contact N1, as shown in Figure 7, the switching element T1, inductor L, and circulating diode D are not connected, and a DC voltage U is directly supplied to the EDS 300. dc When switch S is connected to the second contact N2, as shown in Figure 8, switching element T1, inductor L, and circulating diode D are connected, supplying DC voltage U to EDS 300. dc The DC voltage after step-down processing.

[0072] In this embodiment, the switching element T1 is turned on and off by the drive pulse output by the control circuit. When the control circuit outputs a high level pulse, the switching element T1 is driven to a high level, and the switching element T1 is turned on. The anode voltage of the circulating diode D is less than the cathode voltage, and the circulating diode D is reverse-biased and cut off. The current flowing through the switching element T1 flows through the inductor L, and the inductor L is magnetized. The current flowing through the inductor L increases linearly, while simultaneously charging the capacitor C and supplying power to the EDS 300. During this period, the current in the inductor L gradually increases, and a self-induced electromotive force with the left end positive and the right end negative is generated at the two ends of the inductor L to hinder the current increase. The inductor L converts electrical energy into magnetic energy and stores it.

[0073] After conduction time t onAfterwards, the control circuit pulse is low, the switching element T1 is driven low, and the switching element T1 is open. The current in inductor L cannot change abruptly, and a self-induced electromotive force (EMF) is generated across inductor L, with the right end positive and the left end negative, hindering the current decrease. This causes the circulating diode D to be forward biased and conduct. The current in inductor L flows through the circulating diode D, forming a loop, and the current value gradually decreases. The magnetic energy stored in inductor L is converted into electrical energy and released to supply EDS 300. After the turn-off time t... off Afterwards, the control circuit pulse goes high again, turning on switching element T1, and the above process repeats. The PWM period is T. s T s =t on +t off d = t on / T s It is the duty cycle of the PMW wave, which can be changed to change the output voltage, thereby supplying an adjustable DC voltage to the EDS 300.

[0074] The capacitor C reduces output voltage ripple, and the circulating diode D prevents the inductor L from developing a high self-induced electromotive force (EMF) when the switching element T1 changes from on to off, thus preventing damage to the inductor L. Specifically, the circulating diode D protects components from breakdown or burnout by induced voltage. It is connected in parallel to the components generating the induced EMF, namely the inductor L and the capacitor C, forming a circuit. The high EMF generated is dissipated in the circuit as a continuous current, thereby protecting the components in the circuit, namely the inductor L and the capacitor C, from damage. The circulating diode D can be, for example, a fast recovery diode or a Schottky diode.

[0075] In one possible implementation, as shown in Figure 9, the chopper circuit 2121 includes a switching element T2, an inductor L, a capacitor C, and a circulating diode D. The switching element T2 is an IGBT field-effect transistor, and this is one implementation of the first switching element.

[0076] When switch S is connected to the first contact N1, as shown in Figure 7, switch element T2, inductor L, and circulating diode D are not connected, and DC voltage U is directly supplied to EDS 300. dc When switch S is connected to the second contact N2, as shown in Figure 10, switching element T2, inductor L, and circulating diode D are connected, supplying DC voltage U to EDS 300. dc The DC voltage after step-down processing. The only difference between Figure 9 and Figure 6 is that the switching element T1 is replaced by the switching element T2. The working principle of the chopper circuit 2121 for step-down processing can be found in the previous description of Figure 6, and will not be repeated here.

[0077] In one possible implementation, as shown in Figure 11, the chopper circuit 2121 includes a switching element T3, an inductor L, a capacitor C, and a switching element T4 between the positive and negative terminals of the DC power supply module 100. The switching elements T3 and T4 form a half-bridge module, wherein both the switching elements T3 and T4 are IGBT field-effect transistors, and the switching elements T3 and T4 are respectively an implementation of the first switching element and the second switching element.

[0078] When switch S is connected to the first contact N1, as shown in Figure 7, switch element T3, inductor L, and switch element T4 are not connected, and DC voltage U is directly supplied to EDS 300. dc When switch S is connected to the second contact N2, as shown in Figure 12, switching element T3, inductor L, and switching element T4 are connected, supplying DC voltage U to EDS 300. dc The DC voltage after step-down processing. The only difference between Figure 11 and Figure 9 is that the circulating diode D is replaced by the switching element T4. The working principle of the chopper circuit 2121 for step-down processing can be found in the previous description of Figure 9, and will not be repeated here.

[0079] As shown in Figure 13, when switch S is connected to the first contact N1, the power supply mode is the first mode, and the DC voltage supplied to EDS 300 is U. dc The corresponding current is 0 to I. dc When switch S is connected to the second contact N2, the power supply mode is the second mode, and the DC voltage supplied to EDS 300 is U. min ~U max The corresponding current is I min ~I max U max < dc I max < dc .

[0080] As shown in Figure 14, in the low speed and low torque region (low speed and low power region, especially in urban operating conditions), the second mode can be used as the power supply mode, while in the medium and high speed and medium and high torque region (medium and high speed and medium and high power region), the first mode can be used as the power supply mode.

[0081] ​​Figures 15 and 16 show two sets of EDS or EMDU (motor drive unit) efficiencies measured when a constant DC voltage of 786V and an adjustable DC voltage (450V in the small boxes, 786V elsewhere) are supplied to the EDS 300 in the low-speed, low-torque region. Comparing Figures 15 and 16, it is clear that the efficiency at 450V is significantly higher than that at 786V, representing an efficiency improvement of at least 2%. It should be understood that Figure 16 shows efficiency data obtained by directly reducing the supplied DC voltage from 786V to 450V. In practice, if the power control circuit 200 of this invention is used, the DC voltage supplied to the EDS 300 can be reduced even further, for example, to 100V, resulting in a greater efficiency improvement.

[0082] Therefore, the power control circuit 200 and its power control system of the present invention can effectively improve WLTC efficiency and also improve voltage utilization.

[0083] Figure 17 shows the fundamental voltage required for operation in the low-speed, low-torque region. It can be seen that the power control circuit 200 can determine the actual required DC voltage based on the rotational speed and torque, and reduce the DC voltage supplied by the DC power module 100 to the required DC voltage. Furthermore, the DC power module 100 (step-down processing unit) generates some switching and conduction losses when chopping the DC voltage, but no iron losses are generated in power electronic devices. Therefore, as shown in Figure 16, the efficiency can reach over 98%. Simultaneously, it can also be seen from Figure 16 that the efficiency improvement is much greater than 2% due to the reduction of PWM harmonic iron losses.

[0084] As shown in Figure 18, it illustrates the mechanical power required for operation in the low-speed, low-torque region. This means that the power electronic components only need to be designed based on about 20 kilowatts instead of 200 kilowatts, so the above-described solution of the present invention is also available in terms of cost.

[0085] In one possible implementation, this embodiment provides an electric vehicle including the power control system described above; a vehicle controller (VCU) for determining whether the control conditions are met based on the operating speed of the electric vehicle and the torque of the motor; if the control conditions are met, determining the DC voltage to be adjusted based on the operating speed, the torque, and the DC voltage supplied by the DC power module 100, and issuing a command to the control module 210 to instruct the EDS 300 to supply the determined DC voltage via the DC power module 100 as the adjustable DC voltage.

[0086] In this embodiment, the VCU determines whether the control conditions are met based on the vehicle's operating speed and the motor's torque. When the control conditions are met, it determines that the second mode should be used as the power supply mode. It can also determine the actual required DC voltage based on the speed, torque, and the DC voltage supplied by the DC power module 100, and issue a command to switch the power supply mode to the second mode. In this command, the value of the adjusted DC voltage can also be indicated.

[0087] In one possible implementation, the VCU is configured to: determine that control conditions are met when the operating speed is below a speed threshold and the torque is below a torque threshold, and determine the DC voltage to be adjusted based on the operating speed, the torque, and the DC voltage supplied by the DC power module 100; and determine that control conditions are not met when the operating speed is above a speed threshold and the torque is above a torque threshold, and issue a command to the control module 210 instructing a constant DC voltage to be supplied to the EDS 300 via the DC power module 100. An operating speed below a speed threshold indicates a low vehicle speed, and a torque below a torque threshold indicates a low motor torque. A vehicle operating at a speed below the speed threshold and a torque below the torque threshold is, for example, operating under urban conditions; therefore, the VCU determines that the control conditions are met.

[0088] In one possible implementation, the switching unit 211 can be a single-contact switch S. Figure 19 shows a schematic diagram of another power control system according to this exemplary embodiment. By comparing Figures 19 and 11, it can be seen that the only difference between Figure 19 and Figure 11 is that the switch S is replaced from a dual-channel switching switch to a single-contact switch, and on this basis, the switching element T3 is directly connected to the anode of the DC power module 100.

[0089] As shown in Figure 19, when the single-contact switch S is closed, the transformer processing unit, including switching element T3, inductor L, capacitor C, and switching element T4, is open-circuited. The DC power module 100 is directly connected to the EDS 300 without going through the transformer processing unit. The DC voltage U from the DC power module 100... dc It is directly output to EDS 300. When the single-contact switch S is open, the power supply mode is the second mode. A schematic diagram of the power control system in the second mode can be seen in Figure 20.

[0090] As shown in Figure 20, the transformer processing unit, including switching element T3, inductor L, capacitor C, and switching element T4, operates. The DC power module 100 is connected to the EDS 300 via this transformer processing unit. The transformer processing unit converts the DC voltage U from the DC power module 100... dc Reduce the DC voltage to the required level and output that required DC voltage to the EDS 300.

[0091] As shown in Figure 21, when the single-contact switch S is closed, the transformer processing unit (simplified as T in Figure 21), including switching element T3, inductor L, capacitor C, and switching element T4, is open-circuited, the power supply mode is the first mode, and the DC voltage supplied to EDS 300 is U. dc The corresponding current is 0 to I. dc When the single-contact switch S is open, the transformer processing unit (simplified as T in Figure 21), including switching element T3, inductor L, capacitor C, and switching element T4, operates in the second power supply mode, and the DC voltage supplied to the EDS 300 is U. min ~U max The corresponding current is I min ~I max U max < dc I max < dc It should be noted that the specific configuration of the switching unit described above is merely an example, and the present invention is not limited thereto. Those skilled in the art can flexibly select appropriate components as the switching unit according to actual application requirements.

[0092] Therefore, according to the power control circuit, power control system, and electric vehicle of the present invention, compared to supplying a constant DC voltage to the EDS via a DC power module when the control conditions for supplying an adjustable DC voltage to the EDS are met, the present invention supplies an adjustable DC voltage to the EDS via a DC power module when the control conditions are met. This effectively reduces the voltage supplied to the EDS, thereby not only improving voltage utilization but also increasing the PWM duty cycle of the bus voltage, reducing PWM harmonic losses, and thus effectively improving WLTC efficiency. In this way, both voltage utilization and WLTC efficiency can be simultaneously achieved.

[0093] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.​​

Claims

1. A power supply control circuit, characterized in that, An electric drive system (EDS) that is supplied with DC voltage via a DC power module includes a power control circuit comprising: A control module is configured to control the supply of the adjustable DC voltage to the EDS via the DC power supply module, provided that control conditions for supplying an adjustable DC voltage to the EDS are met.

2. The power control circuit according to claim 1, characterized in that, The control module is configured to: if the control conditions are met, perform control to supply the adjustable DC voltage to the EDS via the DC power module while stepping down the DC voltage supplied by the DC power module, wherein the adjustable DC voltage is the DC voltage obtained after stepping down the DC voltage supplied by the DC power module.

3. The power control circuit according to claim 1, characterized in that, If the control conditions are not met, the control module controls the supply of a constant DC voltage to the EDS via the DC power module, wherein the constant DC voltage is greater than the adjustable DC voltage.

4. The power control circuit according to claim 3, characterized in that, The control module is configured to: if the control conditions are not met, perform control to supply the constant DC voltage to the EDS via the DC power module without stepping down the DC voltage supplied by the DC power module, wherein the constant DC voltage is the DC voltage supplied by the DC power module.

5. The power control circuit according to any one of claims 1-4, characterized in that, The control module includes: A voltage reduction processing unit is used to step down the DC voltage supplied by the DC power supply module. A switching unit is configured to connect between the DC power supply module and the EDS when connected to the transformer processing unit if the control conditions are met, and to connect between the DC power supply module and the EDS when not connected to the transformer processing unit if the control conditions are not met.

6. The power control circuit according to claim 5, characterized in that, The transformer processing unit includes a chopper circuit, which is used to step down the DC power supplied by the DC power module. The chopper circuit has a series circuit of a first switching element for stepping down, an inductor, and a capacitor between the positive and negative terminals of the DC power module.

7. The power control circuit according to claim 6, characterized in that, The chopper circuit also has a circulating diode between the positive and negative terminals of the DC power module, and the circulating diode is connected between the connection point between the first switching element and the inductor and the negative terminal of the DC power module.

8. The power control circuit according to claim 6, characterized in that, The chopper circuit also has a second switching element between the positive and negative terminals of the DC power module, wherein the second switching element and the first switching element form a half-bridge module, and the second switching element is connected between the connection point between the first switching element and the inductor and the negative terminal of the DC power module.

9. A power supply control system, characterized in that, It includes a DC power supply module according to any one of claims 1-8, the power control circuit, and the EDS, wherein the EDS includes an inverter and a motor.

10. An electric vehicle, characterized in that, include: The power control system according to claim 9; The vehicle control unit (VCU) is used to determine whether the control conditions are met based on the operating speed of the electric vehicle and the torque of the motor. If the control conditions are met, the VCU determines the DC voltage to be adjusted based on the operating speed, the torque, and the DC voltage supplied by the DC power module, and issues a command to the control module to instruct the EDS to supply the determined DC voltage via the DC power module as the adjustable DC voltage.

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