Vehicle-mounted multi-path DC-DC output system and method for new energy vehicle

Abstract

This invention discloses an on-board multi-channel DC-DC output system for new energy vehicles, comprising: a phase-shifting full-bridge converter; an LCC resonant network; a wireless power coupler; a series resonant network connected to the wireless power coupler; positive and negative half-wave rectifiers composed of bidirectional switches connected to the wireless power coupler and the series resonant network; and a synchronous rectifier bridge connected to the positive and negative half-wave rectifiers composed of bidirectional switches. The positive and negative half-wave rectifiers composed of bidirectional switches and the synchronous rectifier bridge constitute channels #A, #B, and #C. This invention integrates two half-wave rectifiers into a single branch through two anti-series power transistors, saving space on the receiving side and improving system performance.

Description

Technical Field

[0001] This invention relates to the field of on-board DC-DC technology for new energy vehicles and the field of wireless power transmission, specifically to an on-board multi-channel DC-DC output system and method for new energy vehicles. Background Technology

[0002] In recent years, the new energy vehicle market has experienced rapid growth, with a penetration rate exceeding 50%. In addition to requiring efficient transmission and simple control, on-board DC-DC systems have different requirements for different applications. These include input / output isolation, the ability to supply power to loads using various power sources, and flexibility in power usage. With the development of Magnetic Coupled Wireless Power Transfer (MC-WPT) technology and the demands of different application scenarios, its research and application have gradually shifted from the initial single-load wireless power supply mode to a multi-load wireless power supply mode. Compared to single-load MC-WPT technology, multi-load MC-WPT technology offers advantages such as higher power density, higher excitation source utilization, and greater freedom in the spatial location of the receiving load, further improving system compatibility.

[0003] To achieve multiple outputs, one approach is to increase the number of transmission paths by using a Multiple-Input Multiple-Output (MIMO) system. This means that multiple transmitters and multiple receivers are needed to achieve multiple transmissions and outputs, which undoubtedly increases the system size and is detrimental to cost control.

[0004] To save costs, simplify the structure, and reduce cross-coupling issues associated with MIMO systems, the Single-Input-Multi-Output (SIMO) WPT system is currently a popular approach. One method of implementation involves using a single-T or dual-T resonant circuit, employing passive components such as inductors and capacitors to achieve voltage or current transformation. However, this passive topology makes it difficult to regulate the output voltage or current during charging. Summary of the Invention

[0005] This invention provides an on-board multi-channel DC-DC output system and method for new energy vehicles. This invention integrates two half-wave rectifiers into a single branch through two reverse-connected power transistor devices, saving space on the receiving side and improving system performance.

[0006] The technical solution to the above problem is as follows:

[0007] An on-board multi-channel DC-DC output system for new energy vehicles includes a primary-side inverter and a secondary-side synchronous rectifier, wherein the primary-side inverter includes:

[0008] Phase-shifting full-bridge converter;

[0009] The LCC resonant network includes a first compensation coil, a first compensation capacitor, and a second compensation capacitor. One end of the first compensation coil is electrically connected to the phase-shifted full-bridge converter, and one end of the first compensation capacitor is connected to the other end of the first compensation coil.

[0010] A wireless power coupler includes a transmitting coil and a receiving coil. One end of the transmitting coil is connected to the other end of a first compensation coil, and the other end of the transmitting coil is connected to one end of a second compensation capacitor. The other ends of the first and second compensation capacitors are connected to a phase-shifting full-bridge converter.

[0011] The secondary-side synchronous rectifier includes:

[0012] A series resonant network is connected to a wireless power coupler.

[0013] A bidirectional switch-based positive and negative half-wave rectifier is connected to a wireless power coupler and a series resonant network.

[0014] The synchronous rectifier bridge is connected to the positive and negative half-wave rectifiers formed by the bidirectional switch. The positive and negative half-wave rectifiers formed by the bidirectional switch and the synchronous rectifier bridge form channels #A, #B, and #C.

[0015] The method for on-board multiplex DC-DC output for new energy vehicles, applied to the aforementioned on-board multiplex DC-DC output system for new energy vehicles, is as follows:

[0016] The primary controller employs a dual closed-loop control system (voltage and current), a feedforward control loop, and a receiving loop current I. S In the polarity detection stage, two stages respectively perform phase-shift voltage regulation control on the primary-side inverter and synchronous rectification control on channel #A:

[0017] The voltage of channel #B and channel #C is adjusted using a secondary controller.

[0018] Theoretical derivation of the circuit structure of this invention reveals that: resonance is achieved through an LCC-S type compensation topology, ensuring zero-phase input, eliminating reactive power in the primary loop, creating soft-switching conditions, and realizing resonant wireless power transmission; secondly, for multiple different outputs, a control structure including two feedback PI controllers is proposed to achieve independent control of the output voltage, eliminating the need for additional communication equipment and simplifying system control complexity; to overcome input disturbances, a feedforward control strategy is introduced to compensate for input disturbances. Finally, a simulation experimental platform was built, and the system exhibited excellent stability and robustness, verifying the feasibility of the proposed method. This invention not only enables multiple positive and negative DC power outputs with input-output isolation, but also allows for independent control of each DC power output. The system not only has good regulation capability for load changes, but also effectively suppresses input disturbances.

[0019] This invention relates to a SIMO-WPT system based on different types of rectifiers. It includes a synchronous rectifier to achieve positive DC output and a bidirectional switch forming a half-wave rectifier to achieve positive / negative DC power output. The two half-wave rectifiers are integrated into a single branch via two anti-parallel series power transistors, saving space on the receiving side. Two adjustable receiving loops were successfully constructed, enabling applications with varying output power requirements. Furthermore, the system requires no additional detection circuitry or communication equipment, thus achieving a high-performance, cost-effective system. In summary, this invention has the following two innovative aspects:

[0020] (1) Unlike traditional single-input multiple-output, this invention combines a full-wave rectifier and a half-wave rectifier, considering two sets of output channels as a whole (channel #A, channel #B, and channel #C, where channel #B and channel #C constitute a half-wave rectifier, with group B outputting positive power and group C outputting negative power). Specifically, a synchronous rectifier is installed in channel #A, while half-wave rectifiers are installed in channels #B and #C using the positive and negative half-cycles of the AC voltage source, respectively, and the switching between the two half-wave rectifiers can be achieved without multiple sets of circuits.

[0021] (2) In terms of control strategy: For channel #A and channel #B, the present invention uses a composite control strategy of PI control plus feedforward control to achieve constant output voltage control. In particular, channel #A adopts voltage and current dual closed-loop PI control + feedforward compensation to achieve constant output voltage and reduces losses through synchronous rectification. For channel #B and channel #C, by detecting the current flowing through the receiving coil, the two reverse series switching transistors are controlled to turn on and off based on the PI voltage closed-loop controller, which enables the system to have efficient and stable output and meet the requirements of different output circuits. Attached Figure Description

[0022] Figure 1 This is a structural diagram of the vehicle-mounted multi-channel DC-DC output system of the present invention.

[0023] Figure 2a The equivalent circuit diagram for channel #B.

[0024] Figure 2b The equivalent circuit diagram for channel #C.

[0025] Figure 3 A flowchart illustrating the overall control strategy for a vehicle's onboard multi-channel DC-DC output method.

[0026] Figure 4 This is a waveform diagram of the inverter output voltage and current.

[0027] Figure 5a This is the logic diagram for turning on the switching transistors in a phase-shifted full-bridge converter.

[0028] Figure 5b This is a logic diagram showing the conduction of the switching transistors in a positive and negative half-wave rectifier composed of bidirectional switches.

[0029] Figure 6a This is the rectified output voltage of channel #A.

[0030] Figure 6b This is the rectified output voltage of channel #B (channel #C).

[0031] Figure 7a The output voltage waveform of channel #A under load variation.

[0032] Figure 7b The output voltage waveform of channel #B under load variation.

[0033] Figure 8 This is a waveform diagram of the output channel voltage when the input voltage changes.

[0034] Figure 9 For channels #B and #C, the output voltage is... Detailed Implementation

[0035] like Figure 1 As shown, the on-board multi-channel DC-DC output system for new energy vehicles of the present invention includes a primary-side inverter and a secondary-side synchronous rectifier. The primary-side inverter includes a phase-shifting full-bridge converter, an LCC resonant network, and a wireless power coupler. The secondary-side synchronous rectifier includes a series resonant network, a positive and negative half-wave rectifier composed of bidirectional switches, and a synchronous rectifier bridge. The components and their relationships are described in detail below.

[0036] The phase-shifted full-bridge converter includes an inverter body, which includes a first power transistor Q1, a second power transistor Q2, a third power transistor Q3, and a fourth power transistor Q4. The first power transistor Q1 is connected to the second power transistor Q2, the third power transistor Q3 is connected to both the first power transistor Q1 and the fourth power transistor Q4, and the fourth power transistor Q4 is also connected to the second power transistor Q2. In this embodiment, the first power transistor Q1 to the fourth power transistor Q4 are all IGBT switching transistors.

[0037] The LCC resonant network includes a first compensation coil L T First compensation capacitor C T Second compensation capacitor C P First compensation coil L T One end is electrically connected to the phase-shifted full-bridge converter, and the first compensation capacitor C T One end is connected to the first compensation coil L T The other end is connected.

[0038] The wireless power coupler includes a transmitting coil L P Receiver coil L S transmitting coil L P One end is connected to the first compensation coil L T The other end is connected to the transmitting coil L. P The other end is connected to the second compensation capacitor C P One end is connected to the first compensation capacitor C. T Second compensation capacitor C P The other end is connected to the phase-shifted full-bridge converter.

[0039] The series resonant network is connected to the wireless power coupler, and the series resonant network includes a third compensation capacitor C. S The third compensation capacitor C S One end is connected to the receiving coil L S Connection, third compensation capacitor C S The other end is connected to a positive and negative half-wave rectifier consisting of a bidirectional switch.

[0040] A bidirectional switch-based positive and negative half-wave rectifier is connected to a wireless power coupler and a series resonant network. The bidirectional switch-based positive and negative half-wave rectifier includes a first power switch Q. b Second power switch Q c First output capacitor C BC The first power switch Q b Second power switch Q c All are IGBT switching transistors, with the first power switching transistor Q. b With the second power switch Q c Reverse series connection, first output capacitor C BC With the second power switch Qc connect.

[0041] The synchronous rectifier bridge is connected to the positive and negative half-wave rectifiers formed by bidirectional switches. The positive and negative half-wave rectifiers formed by the bidirectional switches and the synchronous rectifier bridge constitute channels #A, #B, and #C. The synchronous rectifier bridge includes the fifth power transistor Q5, the sixth power transistor Q6, the seventh power transistor Q7, the eighth power transistor Q8, and the second output capacitor C. A The fifth power transistor Q5 is connected to the sixth power transistor Q6. The seventh power transistor Q7 is connected to both the fifth power transistor Q5 and the eighth power transistor Q8. The eighth power transistor Q8 is also connected to the sixth power transistor Q6. The second output capacitor C... A One end is connected to the seventh power transistor Q7, and the second output capacitor C A The other end is connected to the eighth power transistor Q8. Power transistors Q5 through Q8 are all IGBT switching transistors.

[0042] For synchronous rectifier bridges, it is typically required that the switching sequence be synchronized with the current direction, i.e., when the rectified current I... S When positive, the fifth power transistor Q5 (sixth power transistor Q6) and the eighth power transistor Q8 (seventh power transistor Q7) should be in the ON (OFF) state; when the rectified current I... S When the current is negative, the sixth power transistor Q6 (fifth power transistor Q5) and the seventh power transistor Q7 (eighth power transistor Q8) should be in the ON (OFF) state; for a positive half-wave rectifier (i.e., channel # B), when the rectified current I... S When positive, the output voltage can be controlled; however, for a negative half-wave rectifier (i.e., channel # C), when the rectified current I... S When it is negative, the output voltage can be controlled.

[0043] For LCC-S type compensation networks, the parameters of their compensation elements satisfy the following relationship:

[0044] (1)

[0045] Among them, C T For the first compensation capacitor, C P For the second compensation capacitor, C S For the third compensation capacitor, L T For the first compensation coil, L P For the transmitting coil, L S For the receiving coil, ω is the operating angular frequency of the inverter, which satisfies ω = 2πf.

[0046] By using the LCC-S type compensation topology, most high-order harmonics are filtered out. To simplify the analysis, this invention employs the fundamental frequency approximation method for theoretical derivation. Using phase-shifted modulation (PSM) to control the inverter, the fundamental component of the inverter output voltage can be written in phasor form as:

[0047] (2)

[0048] In the formula: U in V is the output voltage of the inverter body. dc It is a DC voltage source, and δ is the conduction angle.

[0049] Kirchhoff's voltage and current loop equations for the proposed circuit topology can be written in phasor form as follows:

[0050] (3)

[0051]

[0052] R is the phasor of the output voltage of the inverter body. T R is the parasitic resistance of the first compensation coil, R is the phasor of the primary inverter input current, R is the phasor of the transmitting coil current, R is the phasor of the rectified current, R is the phasor of the secondary AC bus voltage, and R is the phasor of the primary inverter input current. S R is the parasitic resistance of the receiving coil. eq R is the secondary AC equivalent resistance. eqa R is the equivalent resistance of channel # A. eqb The equivalent resistance R of channel #B eqc For the equivalent resistance of channel #C, the following results can be obtained:

[0053] (4)

[0054] Where R a R is the equivalent resistance of channel # A. b The equivalent resistance R of channel #B c U is the equivalent resistance of channel # C. S It is the secondary side AC bus voltage, V b V is the output voltage of channel #B. c This is the output voltage of channel #C.

[0055] Substituting equations (1) and (2) into equation (3), we can obtain U S I T Phasor expressions:

[0056] (5)

[0057] X M = X CT = M is the mutual inductance between the transmitting coil and the receiving coil, and R... P This is the parasitic resistance of the transmitting coil.

[0058] Regarding channel #A, based on the relationship between the input and output voltages of the synchronous rectifier bridge, the rectified voltage V... a It can be represented in the following form:

[0059] (6)

[0060] Figure 2a The equivalent circuit of output channel #B is given. Figure 2b The equivalent circuit of output channel #C is given, where U S This refers to the secondary side AC bus voltage.

[0061] from Figure 2a and Figure 2b As can be seen, the SIMO-WPT proposed in this invention integrates output channels #B and #C into a single circuit, which undoubtedly reduces additional components and the volume occupied. Moreover, the switching between the positive half-wave rectifier (channel #B) and the negative half-wave rectifier (channel #C) can be achieved simply by controlling the turn-on and turn-off of two reverse-connected switching transistors. The specific control strategy will be described in detail later.

[0062] The output voltage V of channel #B (positive half-wave rectifier) b It can be represented in the following form:

[0063] (7)

[0064] Where D Qb It is the duty cycle of the pulse width modulation during the positive half-cycle of channel #B.

[0065] Similarly, the output voltage V of channel #C (negative half-wave rectifier) c It can be represented in the following form:

[0066] (8)

[0067] In the formula: D Qc This represents the duty cycle of pulse width modulation during the negative half-cycle of channel #C.

[0068] The system's input impedance Z in It can be given by the following formula:

[0069] (9)

[0070] By calculating equations (4), (7), and (8), the following R can be obtained. eq :

[0071] (10)

[0072] As can be seen from (9) and (10), due to R eq It is purely resistive, Z in It is also purely resistive, which means that the entire system can achieve zero-phase input (ZPA).

[0073] like Figure 3 As shown, the on-board multiplex DC-DC output method for new energy vehicles of the present invention is applied to the aforementioned on-board multiplex DC-DC output system of new energy vehicles, and the process is as follows:

[0074] The primary controller employs a dual closed-loop control system (voltage and current), a feedforward control loop, and a receiving loop current I. S In the polarity detection stage, two stages respectively perform phase-shift voltage regulation control on the primary-side inverter and synchronous rectification control on channel #A:

[0075] The voltage of channel #B and channel #C is adjusted using a secondary controller.

[0076] The process of phase-shift voltage regulation control is as follows:

[0077] 1) Use the A / D module of the DSP controller to sample the rectified voltage V of channel #A. a With rectified current I a The acquired signal is then fed back to the primary controller, a voltage and current dual closed-loop controller based on PI control.

[0078] 2) The controller picks up the rectified voltage V a With rectified current I a The signal will rectify the voltage V. a With reference output voltage V aref The resulting error is fed into the PI controller, and after being controlled by the voltage outer loop, the input signal is compared with the reference output current I. aref The error signal is then sent to the inner loop PI controller for comparison.

[0079] 3) To perform feedforward control, first obtain an approximate model of the controlled system. The closer this model is to the real system, the more obvious the control effect. Assume the frequency domain model of a controlled object is as follows:

[0080] (11)

[0081] Where A and B are system constants, and S is a complex frequency domain variable.

[0082] Since the feedforward controller is the reciprocal of the controlled object, the input-output expression of the feedforward controller is derived as follows:

[0083] (12)

[0084] Among them, U f x(t) is the output expression of the feedforward controller, and x(t) is the time-domain expression of the controlled object. By discretizing x(t), we can obtain the output formula of the feedforward controller. The input of the feedforward controller is the setpoint, as shown below:

[0085] (13)

[0086] T is the period of the controlled object, k is the current time sampling point, x(k), x(k-1), and x(k-2) are the expressions of the controlled object at sampling points k, k-1, and k-2, respectively, and U f (k) is the output expression of the feedforward controller at sampling point k. The corresponding feedforward control parameters can be set according to the actual system requirements; the rectified voltage V is obtained from the following formula. a and DC voltage source V dc Relationship with phase shift angle:

[0087] (14)

[0088] Obtain the rectified voltage V a and DC voltage source V dc The relationship between the phase angle and the phase shift angle is:

[0089] (15)

[0090] U s For the secondary side AC bus voltage, C T For compensation capacitance, M is the mutual inductance between the transmitting and receiving coils, and U... in V is the output voltage of the phase-shifted full-bridge converter. dc σ is a DC voltage source, ω is the phase shift angle, and ω is the operating angular frequency of the inverter.

[0091] The phase shift angle in equation (15) can be changed by feedforward control, thereby accelerating the response speed of the DC-DC system.

[0092] 4) The input signal after voltage and current dual closed-loop control and feedforward control is generated by the PWM generator into two pairs of complementary PWM pulse waves, which control the turn-on and turn-off of the upper and lower transistors of the front and rear bridge arms of the primary inverter respectively.

[0093] The specific control process for the synchronous rectification of channel #A is as follows:

[0094] 1) Use the DSP controller's A / D conversion module to sample the receiving coil current and determine the rectified current I. S The polarity of.

[0095] 2) According to I S The different polarities generate two pairs of complementary PWM pulse waves, when the rectified current I... S When the current is greater than 0, the fifth power transistor Q5 and the eighth power transistor Q8 in the synchronous rectifier bridge are turned on; when the rectified current I... S When the value is less than 0, the sixth power transistor Q6 and the seventh power transistor Q7 of the synchronous rectifier bridge are turned on.

[0096] Through the above logical judgment, synchronous rectification of channel #A is achieved.

[0097] The process of the secondary controller adjusting the voltage of channel #B and channel #C is as follows:

[0098] (1) First, set the rectified current I S When <0, channel #B is turned on, and when the rectified current I... S When the value is greater than 0, channel #C is activated.

[0099] (2) The secondary controller uses the A / D module of the DSP controller to sample the output voltage V of channel #B. b and the output voltage V of channel #C c The preset output voltage is calculated by subtracting the sampled output voltage, and the error information is sent to the PI controller. This error is then controlled by the D... Qb and D Qc Adjust the voltage V respectively b and V c ;

[0100] In the above, D Qb It is the duty cycle of pulse width modulation in the positive half-cycle of channel #B, D Qc This represents the duty cycle of pulse width modulation during the negative half-cycle of channel #C.

[0101] To verify the feasibility of the proposed SIMO-WPT system, a simulation model was built using Matlab / Simulink software, and the results were analyzed. The system simulation parameters are shown in Table 1, which provides examples of the units and values ​​of the parameters used in the above formulas.

[0102] Table 1 System Simulation Parameters

[0103]

[0104] The simulation data given in Table 1 can provide a good reference basis for subsequent experimental verification.

[0105] ZPA Verification

[0106] As shown in equations (9) and (10), the input impedance of the system designed in this invention exhibits a purely resistive load, meaning the system achieves zero-phase input. To verify this theory, a simulation model was built for verification, and the results are as follows: Figure 4 As shown.

[0107] from Figure 4 It can be seen that after inversion, the output voltage and current are basically in phase, indicating that the input impedance of the system has eliminated the imaginary part and exhibits the characteristics of a purely resistive load, thus achieving ZPA.

[0108] Control strategy verification

[0109] This invention employs two controllers, a primary controller and a secondary controller, whose functions are respectively to control the inverter for phase-shift voltage regulation, to achieve synchronous rectification (#A), and to control the switching of channels #B and #C, thereby enabling the output voltage of both channels to quickly stabilize to the reference voltage. The output pulse waveforms of the phase-shift voltage regulation switch and the output pulse waveforms of the channel #B and #C switches are shown below. Figure 6a and Figure 6b As shown.

[0110] Figure 5a This demonstrates the PWM output pulse under dual closed-loop control of voltage and current, and feedforward control. The first power transistor Q1 and the second power transistor Q2 are the switches for the front and rear upper arms of the bridge, respectively. After passing through the voltage outer loop, the current inner loop control, and the feedforward control, the input signal is sent to the PWM generator. The generator performs phase-shift voltage regulation based on the signal difference, enabling the system to react quickly and control the on and off of the switches from the first power transistor Q1 to the fourth power transistor Q4.

[0111] Figure 5b The display shows the PWM output pulses of control channels #B and #C, and the first power switch Q. b Second power switch Q c These are forward and reverse switching transistors, respectively. The polarity of the receiving coil current is detected to control the on and off states of the two reverse-connected switching transistors.

[0112] The rectified output voltages of channels #A and #B (#C) are as follows: Figure 6a , 6b As shown. Figure 6a This is the rectified output voltage of channel #A. Figure 6b The rectified output voltage of channel #B (#C).

[0113] exist Figure 6a , 6bIn the diagram, the output reference voltage of channel #A is set to 100V, and the output reference voltage of channel #B (#C) is set to 50V. As shown in the figure, after being controlled by the control strategy proposed in this invention, the two output voltage channels of the circuit can quickly respond and reach the ideal voltage value, verifying the feasibility of the proposed method and demonstrating its ability to meet the increasingly diverse power consumption needs.

[0114] Dynamic response verification

[0115] (a) Verification of independent output power adjustment

[0116] Dynamic adjustment capability is a key factor in measuring system stability. Figure 7a , Figure 7b The inverter output voltage and current waveforms and the output voltage waveforms of the rectifier side of the two circuits are given when the load of channel #A and channel #B fluctuates.

[0117] exist Figure 7a In the experiment, the rectified output voltage of channel #A is set to 120V, and the load is switched from 10Ω to 20Ω. The rectified output voltage of channel #B is set to 40V, while its load remains unchanged at 10Ω. Observe the results. Figure 7a It can be seen that when the load changes in channel #A, its rectified output voltage fluctuates slightly at the load switching point and then immediately remains unchanged at 120V, while the rectified output voltage of channel #B remains unchanged at 40V. At this time, the primary controller also controls the phase shift angle to change and performs phase shift voltage regulation.

[0118] exist Figure 7b In the experiment, the rectified output voltage of channel #B is set to 60V, and the load is switched from 5Ω to 10Ω. The rectified output voltage of channel #A is set to 100V, and its load remains unchanged at 20Ω. Observe the results. Figure 7b It can be seen that when the load of channel #B changes, its rectified output voltage remains unchanged at 60V, while the rectified output voltage of channel #A remains unchanged at 100V. Similarly, the primary controller also performs phase-shift voltage regulation control.

[0119] The above results demonstrate that, using the circuit topology and control strategy proposed in this invention, different output loops can independently adjust their output power according to requirements, without being affected by other loops.

[0120] (b) Verification of constant output voltage under input voltage fluctuations

[0121] In practical applications, voltage fluctuations due to grid-side imbalances can cause instability in the input voltage, leading to overall system output instability. Therefore, it is necessary to control this fluctuation. Figure 8 The voltage waveforms of the two output channels #A and #B are shown when the input voltage fluctuates.

[0122] exist Figure 8 In the configuration, the input voltage is switched from 120V to 100V. The rectified output voltage of channel #A is 100V, and the rectified output voltage of channel #B is 60V. Figure 8 It can be seen that when the input voltage changes, the output voltage of the two channels remains unaffected and remains constant, proving that the proposed system has good anti-interference capability and can adapt to relatively extreme power consumption scenarios.

[0123] (c) Verification of multiple positive / negative DC power outputs

[0124] In this invention patent, channel #B is configured as a positive power supply rectified output, and channel #C is configured as a negative power supply rectified output. Figure 9 The output waveforms of channels #B and #C are displayed.

[0125] Depend on Figure 9 As shown in the figure, the rectified output of channel #A is set to 100V, the positive voltage output of channel #B is 60V, and the negative voltage output of channel #C is -60V. Observing the figure above, it can be seen that when channel #B and channel #C switch, the output voltage of channel #A fluctuates slightly during the switching of channel #B and channel #C. In practice, this is within the specified error range. Both channel #B and channel #C can respond quickly and reach the set output voltage. The system responds rapidly and has good dynamic adjustment capability.

[0126] Summarize

[0127] This invention provides a multi-channel DC-DC output system for new energy vehicles. First, two sets of adjustable output channels are successfully constructed, comprehensively considering different types of rectifiers, including a set of synchronous rectifiers to achieve one DC output and a set of half-wave rectifiers to achieve positive / negative DC power output. Then, an LCC-S type compensation topology is used to achieve resonance, and the conditions for the system to achieve ZPA (Zero-Point Power Achievement) are theoretically derived. A feedforward-feedback composite control strategy is proposed, consisting of primary and secondary controllers, enabling the system to respond quickly and achieve stable output under load and input disturbances. Finally, a simulation model is built to verify the effectiveness of the proposed circuit topology and control strategy in achieving multi-channel output regulation.

[0128] The above embodiments are some embodiments of the present invention. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be simply construed as limiting the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A method for on-board multi-channel DC-DC output for new energy vehicles, characterized in that, Includes the following steps: 1) Establish an on-board multi-channel DC-DC output system for new energy vehicles. This system includes a primary-side inverter and a secondary-side synchronous rectifier. The primary-side inverter includes: Phase-shifting full-bridge converter; The LCC resonant network comprises a first compensation coil (L T ), a first compensation capacitor (C T ), a second compensation capacitor (C P ), one end of the first compensation coil (L T ) is electrically connected with the phase-shifted full-bridge converter, and one end of the first compensation capacitor (C T ) is connected with the other end of the first compensation coil (L T ). Wireless power coupler, the wireless power coupler includes a transmitting coil (L P ), receiving coil (L) S ), transmitting coil (L P One end of ) is connected to the first compensation coil (L) T The other end is connected to the transmitting coil (L) P The other end of the capacitor is connected to the second compensation capacitor (C). P One end of the capacitor is connected to the first compensation capacitor (C). T ) and second compensation capacitor (C P The other end is connected to the phase-shifted full-bridge converter; The secondary-side synchronous rectifier includes: A series resonant network is connected to a wireless power coupler. A bidirectional switch-based positive and negative half-wave rectifier is connected to a wireless power coupler and a series resonant network. The synchronous rectifier bridge is connected to the positive and negative half-wave rectifiers formed by the bidirectional switch. The positive and negative half-wave rectifiers formed by the bidirectional switch and the synchronous rectifier bridge form channels #A, #B, and #C. 2) The primary controller includes a dual closed-loop control system for voltage and current, a feedforward control loop, and a receiving loop current I. S In the polarity detection stage, two stages respectively perform phase-shift voltage regulation control on the primary-side inverter and synchronous rectification control on channel #A: The voltages of channels #B and #C are adjusted using a secondary controller; The phase-shift voltage regulation control process is as follows: 1) Use the A / D module of the DSP controller to sample the rectified voltage V of channel #A. a With rectified current I a The collected signal is then fed back to the primary controller, which is a voltage and current dual closed-loop controller based on PI control. 2) The controller picks up V a I a The signal will rectify the voltage V. a With reference output voltage V aref The resulting error is fed into the PI controller, and after being controlled by the voltage outer loop, the input signal is compared with the reference output current I. aref The error signal is then sent to the inner loop PI controller for comparison. 3) To perform feedforward control, first obtain an approximate model of the controlled system. Assume the frequency domain model of the controlled object is as follows: ； Where A and B are system constants, and S is a complex frequency domain variable; Since the feedforward controller is the reciprocal of the controlled object, the input-output expression of the feedforward controller is derived as follows: ； Among them, U f x(t) is the output expression of the feedforward controller, and x(t) is the time-domain expression of the controlled object. By discretizing x(t), we can obtain the output formula of the feedforward controller. The input of the feedforward controller is the setpoint, as shown below: ； T is the period of the controlled object, k is the current time sampling point, x(k), x(k-1), and x(k-2) are the expressions of the controlled object at sampling points k, k-1, and k-2, respectively, and U f (k) is the output expression of the feedforward controller at sampling point k; Based on the actual system requirements, the corresponding feedforward control parameters can be set; V can be obtained from the following formula. a and V dc Relationship with phase shift angle: ； ； U s For the secondary side AC bus voltage, C T For compensation capacitance, M is the mutual inductance between the transmitting and receiving coils, and U... in V is the output voltage of the phase-shifted full-bridge converter. dc For DC voltage source, σ is phase shift angle, and ω is the operating angular frequency of inverter; 4) The input signal after voltage and current dual closed-loop control and feedforward control is generated by the PWM generator into two pairs of complementary PWM pulse waves, which control the turn-on and turn-off of the upper and lower transistors of the front and rear bridge arms of the primary inverter respectively.

2. The on-board multi-channel DC-DC output method for new energy vehicles according to claim 1, characterized in that, The phase-shifted full-bridge converter includes an inverter body, which includes a first power transistor (Q1), a second power transistor (Q2), a third power transistor (Q3), and a fourth power transistor (Q4). The first power transistor (Q1) is connected to the second power transistor (Q2), the third power transistor (Q3) is connected to both the first power transistor (Q1) and the fourth power transistor (Q4), and the fourth power transistor (Q4) is also connected to the second power transistor (Q2).

3. The on-board multi-channel DC-DC output method for new energy vehicles according to claim 1, characterized in that, The series resonant network includes a third compensation capacitor (C). S ), third compensation capacitor (C S One end of the receiver coil (L) is connected to the receiving coil. S ) connection, third compensation capacitor (C S The other end is connected to a positive and negative half-wave rectifier consisting of a bidirectional switch.

4. The on-board multi-channel DC-DC output method for new energy vehicles according to claim 1, characterized in that, The bidirectional switch-based positive and negative half-wave rectifier includes a first power switch (Q). b ), second power switch (Q) c ), first output capacitor (C) BC ), first power switch (Q) b ) and the second power switch (Q) c ) in reverse series, the first output capacitor (C) BC ) and the second power switch (Q) c )connect.

5. The on-board multi-channel DC-DC output method for new energy vehicles according to claim 1, characterized in that, The synchronous rectifier bridge includes the fifth power transistor (Q5), the sixth power transistor (Q6), the seventh power transistor (Q7), the eighth power transistor (Q8), and the second output capacitor (C). A The fifth power transistor (Q5) is connected to the sixth power transistor (Q6), the seventh power transistor (Q7) is connected to both the fifth power transistor (Q5) and the eighth power transistor (Q8), and the eighth power transistor (Q8) is also connected to the sixth power transistor (Q6). The second output capacitor (C) A One end of the capacitor is connected to the seventh power transistor (Q7), and the second output capacitor (C) is connected to the seventh power transistor (Q7). A The other end of the transistor is connected to the eighth power transistor (Q8).

6. The on-board multi-channel DC-DC output method for new energy vehicles according to claim 1, characterized in that, The specific control process for synchronous rectification in channel #A is as follows: 1) Use the DSP controller's A / D conversion module to sample the receiving coil current and determine the rectified current I. S polarity; 2) According to I S The different polarities generate two pairs of complementary PWM pulse waves, when the rectified current I... S When the value is greater than 0, the fifth power transistor (Q5) and the eighth power transistor (Q8) in the synchronous rectifier bridge are turned on; When the rectified current I S When the value is less than 0, the sixth power transistor (Q6) and the seventh power transistor (Q7) of the synchronous rectifier bridge are turned on; Through the above logical judgment, synchronous rectification of channel #A is achieved.

7. The on-board multi-channel DC-DC output method for new energy vehicles according to claim 1, characterized in that, The process of adjusting the voltage of channel #B and channel #C by the secondary controller is as follows: (1) First, when the rectified current I S When <0, channel #B is turned on, and when the rectified current I... S When the value is >0, channel #C is activated; (2) The secondary controller uses the A / D module of the DSP controller to sample the output voltage V of channel #B. b and the output voltage V of channel #C c The preset output voltage is calculated by subtracting the sampled output voltage, and the error information is sent to the PI controller. This error is then controlled by the D... Qb and D Qc Adjust the voltage V respectively b and V c ; In the above, D Qb It is the duty cycle of pulse width modulation in the positive half-cycle of channel #B, D Qc This represents the duty cycle of pulse width modulation during the negative half-cycle of channel #C.

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