Electro-magnetic doubly salient different-voltage direct-current starting power generation system and control method

Abstract

The invention relates to the technical field of direct-current starting power generation, in particular to an electro-magnetic doubly-salient different-voltage direct-current starting power generation system and a control method. An electro-magnetic doubly-salient motor is provided with an excitation winding and an armature winding which are arranged on stator teeth in a sleeving manner; the starting power generation controller is provided with a starting power generation control unit; the starting power generation control unit is electrically connected with the three-phase rectifier bridge, the excitation driver, the three-phase drive axle and the isolating switch respectively; the excitation drive is electrically connected with the excitation winding; one end of the isolation switch is electrically connected with the armature winding and the three-phase rectifier bridge, and the other end is electrically connected with the three-phase drive bridge. Different-voltage design is achieved through the disconnecting switch, the compatibility problem of starting (low voltage) and power generation (high voltage) is solved with low cost, and meanwhile the problems of a high-voltage-withstanding IGBT and complex controllable rectification are avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of DC starting and generating, and particularly to an electrically excited doubly salient variable-voltage DC starting and generating system and a control method therefor. Background Art

[0002] The statements in this section merely provide background technical information related to the present invention and do not necessarily constitute prior art.

[0003] An extended-range electric vehicle is a hybrid vehicle that combines pure electric drive and fuel power generation technologies. On the basis of a pure electric vehicle, it adds a fuel engine as a "range extender". The fuel engine burns fuel, and the generated power drives a generator to generate electricity, thereby extending the vehicle's cruising range. The extended-range electric vehicle solves the problem of cruising range anxiety. Moreover, the bus voltage level of the power battery of electric vehicles is continuously increasing, such as platforms of 380V, 540V, 600V, 700V, etc., making multiple different power supply voltages coexist in the vehicle power supply system.

[0004] In addition to the power generation function, the generator in the range extender also needs to have a starting function and be able to drag the engine to run to the successful ignition speed. Therefore, the rated power of the generator needs to meet the requirements of power battery charging and the operation of the drive motor of the electric vehicle, and also needs to meet the power requirement for dragging the engine when acting as a starter.

[0005] The starting time of the range extender does not exceed 2 seconds. The starting generator works in the electric state for a very short time, and the power required to drag the engine is dozens of times different from the power output by the engine during power generation. For example, the power of the starter equipped with a 2.5L diesel engine is less than 3KW, while the power output for power generation can reach 100Kw and the output voltage is high. If an integrated starting and generating controller is adopted, high-voltage and high-current IGBT tubes need to be selected as the driving switch tubes for the integrated controller, which will increase the cost of the range extender. Secondly, when using this type of controller to drag the engine to start, it is equivalent to using a high-power controller to achieve what a low-power controller can do. During power generation, the IGBT tube is used to achieve controlled rectification, which increases the rectification control difficulty and increases the potential failure modes of IGBT open circuit or short circuit.

[0006] For example, the prior art discloses a starting and generating controller for a doubly salient DC-excited generator and its control method. The generating controller therein includes an IGBT driving circuit, a diode rectifying circuit, an excitation control circuit, a rotor positioning sensor, and an MCU. The diode rectifying circuit is a full-bridge rectifying circuit composed of six diodes, and the IGBT driving circuit is a full-bridge driving circuit composed of six IGBTs. The IGBT driving circuit is coupled with the diode rectifying circuit, that is, the six IGBTs are respectively connected in parallel with the six diodes. For such an integrated starting and generating controller, when applied to a starting generator with a high voltage level, high-voltage withstand IGBT switching tubes need to be selected, increasing the cost of the controller. At the same time, when using IGBTs as controllable rectifying tubes, the control is complex and the open-circuit and short-circuit failure rates are high.

[0007] For example, the prior art discloses a doubly salient high-voltage DC starting and generating system and its control method. The starting generator therein includes a two-section electrically excited doubly salient motor and a permanent magnet exciter connected coaxially. The armature windings of the two-section electrically excited doubly salient motor are respectively connected to a bridge uncontrolled rectifying circuit and then connected in parallel as the generating output end of the starting and generating system. Among them, the three-phase armature windings of the first electrically excited doubly salient motor are sequentially connected to a three-phase full-bridge inverter and a push-pull forward converter. The input end of the push-pull forward converter serves as the starting input end of the starting and generating system, and the permanent magnet exciter provides excitation current for the excitation winding. Its generating control is simple. However, in order to solve the problem of imbalance between the starting power supply voltage and the generating output voltage, the starting circuit adopts a boost control unit from low voltage to high voltage. After boosting to high voltage, high-voltage withstand three-phase full-bridge inverters need to be selected, increasing the control cost and the complexity of control. Summary of the Invention

[0008] In order to solve the technical problems existing in the above-mentioned background art, the present invention provides an electrically excited doubly salient different-voltage DC starting and generating system and its control method. Through a disconnector, a different-voltage design is realized, and the compatibility problem between starting (low voltage) and generating (high voltage) is solved at low cost. At the same time, the pain points of high-voltage withstand IGBTs and complex controllable rectification are avoided.

[0009] In order to achieve the above object, the present invention adopts the following technical solutions: In a first aspect of the present invention, there is provided an electrically excited doubly salient different-voltage DC starting and generating system, including an electrically excited doubly salient motor and a starting and generating controller. The electrically excited doubly salient motor has an excitation winding and an armature winding sleeved on stator teeth. The starting and generating controller has a starting and generating control unit, and the starting and generating control unit is electrically connected to a three-phase rectifier bridge, an excitation drive, a three-phase drive bridge, and a disconnector respectively. The excitation drive is electrically connected to the excitation winding. One end of the disconnector is electrically connected to the armature winding and the three-phase rectifier bridge respectively, and the other end is electrically connected to the three-phase drive bridge.

[0010] Further, the starting and generating control unit is connected to the low-voltage battery through the key switch and is powered by the low-voltage battery after the key switch is turned on; the starting and generating control unit is connected to an external communication interface for receiving instructions.

[0011] Further, the starting and generating control unit is electrically connected to the armature winding through interface P, electrically connected to the excitation drive through interface F, and electrically connected to the excitation drive, three-phase rectifier bridge, filter capacitor, and high-voltage power battery through interface U respectively.

[0012] Further, the three-phase rectifier bridge is electrically connected to the high-voltage power battery, armature winding, filter capacitor, and isolation switch respectively.

[0013] Further, the excitation drive is electrically connected to the excitation winding and is also electrically connected to interface F and interface U of the starting and generating control unit for regulating the DC excitation current.

[0014] Further, the three-phase drive bridge is electrically connected to interfaces P1, P2, and P3 of the starting and generating control unit and the low-voltage battery respectively.

[0015] Further, the isolation switch is an electromagnetic switch or an electronic switch. The electromagnetic switch includes at least a DC relay, a DC contactor, and a solid-state relay, and the electronic switch includes at least IGBT and MOSFET.

[0016] Further, the three-phase rectifier bridge is any one or more of a rectifier diode, a silicon carbide diode, and a Schottky diode.

[0017] Further, the power switch device of the excitation drive is any one of IGBT (Insulated Gate Bipolar Transistor) or MOSFET (Metal Oxide Semiconductor Field Effect Transistor); all the switch devices of the three-phase drive bridge are MOSFET.

[0018] The second aspect of the present invention provides a control method for an electric-excitation doubly salient variable-voltage DC starting and generating system, including: When the starting and generating control unit receives a starting signal from the communication interface, the isolation switch closes, and an electrical connection is established between the three-phase drive bridge, the armature winding, and the three-phase rectifier bridge. The switching signal of the three-phase drive bridge from the low-voltage battery terminal is electrically isolated from the high-voltage battery terminal through the diode in the three-phase rectifier bridge and enters the armature winding. The starting and generating control unit controls the three-phase drive bridge to perform switching commutation on the armature winding by measuring the rotor position, and outputs torque to drive the engine speed to the ignition starting speed; when starting is completed, the isolation switch disconnects the electrical connection between the three-phase drive bridge, the armature winding, and the three-phase rectifier bridge. After successful starting, if the starting and generating control unit receives a generating command, the starting and generating control unit controls the interface F to output a PWM signal with an adjustable duty cycle to control the excitation drive by determining the SOC of the high-voltage power battery through interface U and the rotational speed through interface P, so as to adjust the working voltage of the excitation winding and control the magnitude of the excitation current. The induced electromotive force of the armature winding is rectified by a three-phase rectifier bridge to output a controllable DC voltage and current.

[0019] Compared with the prior art, the above one or more technical solutions have the following beneficial effects: 1. A disconnect switch is introduced between the starting (low-voltage) and generating (high-voltage) circuits to achieve physical isolation. The high- and low-voltage circuits are decoupled through the disconnect switch, simplifying the complexity and realizing that "low-voltage components handle low-voltage tasks, and high-voltage components handle high-voltage tasks". In the starting mode, the disconnect switch is closed, and the armature winding is connected to the three-phase drive bridge and powered by the low-voltage battery to start the engine. In the generating mode, the disconnect switch is opened, and the armature winding is connected to the three-phase rectifier bridge for high-voltage output, avoiding high-voltage backfeeding to the low-voltage side.

[0020] 2. The different-voltage design is realized through the disconnect switch, which solves the compatibility problem between starting (low-voltage) and generating (high-voltage) at low cost, and at the same time avoids the pain points of high-voltage withstand IGBT and complex controllable rectification. During low-voltage starting, the three-phase drive bridge converts the direct current of the low-voltage battery into three-phase alternating current to drive the generator to rotate; because the starting voltage is low (such as 24V), low-voltage withstand and low-cost switching tubes can be selected without high-voltage withstand components (such as IGBT). During high-voltage generating, the three-phase rectifier bridge rectifies the alternating current of the armature winding into high-voltage direct current to directly charge the high-voltage power battery. The three-phase rectifier bridge can use mature high-voltage diodes in the industry, with a cost far lower than that of IGBT, eliminating complex PWM control and unnecessary controllable rectification, thus improving the system reliability. Description of the Drawings

[0021] The specification drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0022] Figure 1 It is a schematic structural diagram of an electric-excitation double salient pole different-voltage DC starting and generating system provided by Embodiment 1 of the present invention; Figure 2 It is a schematic structural diagram of an electric-excitation double salient pole different-voltage DC starting and generating system provided by Embodiment 2 of the present invention.

[0023] In the figure: 1. Starting and generating control unit; 2. Communication interface; 3. Key switch; 4. Low-voltage battery; 5. Three-phase drive axle; 6. Isolating switch; 7. Filter capacitor; 8. Three-phase rectifier bridge; 9. Excitation drive; 10. Excitation winding; 11. Armature winding; 12. High-voltage power battery. Detailed implementation manners

[0024] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0025] It should be noted that the following detailed descriptions are all exemplary and are intended to provide further descriptions of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0026] Term explanation: The wound-field doubly salient electrically excited DC starter / generator is a composite motor that combines a doubly salient structure, an electrically excited technology, and a DC power system. It has both starting and generating functions and is suitable for multi-voltage (heterogeneous voltage) application scenarios.

[0027] Most of the starting generators in range extenders mostly use permanent magnet synchronous motors (including permanent magnet synchronous radial field motors and permanent magnet synchronous axial field motors), and the cost of rare earth permanent magnet materials required for manufacturing such motors has been increasing year by year. The wound-field doubly salient electrically excited DC starter / generator is a doubly salient starting generator that does not use permanent magnet materials but uses electrical excitation. Its rotor has no winding, a concentrated armature winding is sleeved on the stator teeth, the three-phase winding is rectified by diodes, and an excitation winding is installed on the stator yoke or stator teeth. This kind of motor has a simple structure, high reliability, and low cost, and is suitable for the field of electric vehicles.

[0028] The structure and working principle of the wound-field doubly salient electrically excited DC starter / generator are as follows: Doubly salient stator and rotor: Both the stator and the rotor are of salient pole structure (tooth-slot design), without permanent magnets, and rely on the excitation winding to generate a magnetic field; Magnetic field modulation: By rotating the rotor, the reluctance is changed, the magnetic field path is modulated, and the electromechanical energy conversion is realized; The excitation winding is installed on the stator and generates a controllable magnetic field through DC current excitation, and the magnetic field intensity is adjustable (superior to the fixed magnetic field of the permanent magnet); Through multi-winding or tap design, it supports output of different voltage levels (such as 12V / 24V starting, 270V high-voltage generating), meeting the multi-voltage requirements of vehicles / aviation.

[0029] In the starting mode, it operates as a motor and is powered by a battery (power battery). The electro-excitation winding is energized to generate a magnetic field, and the armature current interacts with the magnetic field to generate torque, driving the engine to start. Since the electro-excitation magnetic field is adjustable, it can meet the starting requirements at low temperatures and with large torques.

[0030] In the power generation mode, the engine drives the rotor to rotate, and the stator excitation winding is energized. Alternating current is induced in the armature winding through the change of the double salient pole reluctance, and is rectified to output direct current. During this period, by controlling the magnitude of the excitation current, the output voltage is stabilized to adapt to the load change.

[0031] In the prior art, the controller of the starting generator selects the IGBT tube with high voltage withstand and large current as the driving switch tube. When dragging the engine to start, it is equivalent to using a high-power controller to achieve the function of a low-power controller, increasing the cost of the range extender; when generating power, using the IGBT tube for controllable rectification increases the difficulty of rectification control and increases the potential failure modes of IGBT open circuit or short circuit.

[0032] To solve the above problems, an electro-excitation double salient pole different-voltage DC starting and generating system and control method given in the following embodiments solve the problem that there are multiple different power supply voltages in the vehicle system, resulting in unbalanced starting power supply voltage and generating output voltage. Through the isolation switch, the generating output and electric drive are isolated and work independently; when starting and dragging the engine, a low-voltage three-phase drive bridge is used, which has low cost, and when generating power, a high-voltage three-phase rectifier bridge is used, and the power generation control is simple. At the same time, it solves the problems of increased cost caused by the need to select IGBT switch tubes with high voltage withstand when the starting and generating integrated controller has a high generating output voltage, and the complex control when using IGBT switch tubes for controllable rectification.

[0033] Embodiment 1: This embodiment takes the counterclockwise rotation as the starting direction as an example.

[0034] As shown in Figure 1 An electro-excitation double salient pole different-voltage DC starting and generating system includes an electro-excitation double salient pole motor and a starting and generating controller. Inside the electro-excitation double salient pole motor, there are an excitation winding 10 and an armature winding 11 sleeved on the stator teeth, and the tails of the three-phase armature windings are connected in a Y-shaped connection; inside the starting and generating controller, there are a three-phase rectifier bridge 8, an excitation drive 9, an isolation switch 6, a starting and generating control unit 1, a three-phase drive bridge 5, and a filter capacitor 7.

[0035] The electro-excitation double salient pole motor uses electro-excitation instead of permanent magnet, allowing flexible control of the output voltage by adjusting the excitation current to meet the high and low voltage requirements.

[0036] As a further implementation, the starting and generating control unit 1 is connected to the low-voltage battery 4 through a key switch 3, and is powered by the low-voltage battery after the key switch is turned on.

[0037] As a further implementation, the starting and generating control unit 1 is connected to the communication interface 2 for receiving instructions.

[0038] As a further implementation, the P port of the starting and generating control unit 1 is electrically connected to the armature winding 11.

[0039] As a further implementation, the F port of the starting and generating control unit 1 is electrically connected to the excitation drive 9.

[0040] As a further implementation, the U port of the starting and generating control unit 1 is respectively electrically connected to the excitation drive 9, the three-phase rectifier bridge 8, and the high-voltage power battery 12.

[0041] As a further implementation, the excitation drive 9 is electrically connected to the excitation winding 10, and is also electrically connected to the interface F and interface U of the starting and generating control unit 1 for adjusting the DC excitation current.

[0042] In this embodiment, the excitation drive 9 is used to control the excitation winding current and adjust the motor magnetic field strength. It provides initial excitation in the starting mode, generates a certain magnetic field distribution in the motor, and the magnetic flux forms a closed loop through the stator yoke, stator teeth, air gap, rotor teeth, and rotor yoke; in the generating mode, it adjusts the output voltage (voltage regulation) according to the speed and load, and can control the generating voltage by adjusting the excitation current, without a complex topology.

[0043] As a further implementation, the starting and generating control unit 1 is electrically connected to the isolation switch 6. One end of the isolation switch 6 is electrically connected to the armature winding 11 and the three-phase rectifier bridge 8, and the other end is electrically connected to the three-phase drive bridge 5.

[0044] In this embodiment, the isolation switch 6 is used to physically isolate the high-voltage and low-voltage circuits: Starting mode: The isolation switch is closed, and the armature winding is connected to the three-phase drive bridge (low-voltage inversion) and powered by the low-voltage battery; Generating mode: The isolation switch is opened, and the armature winding is connected to the three-phase rectifier bridge (high-voltage output) to prevent high-voltage backflow to the low-voltage side.

[0045] The isolation switch can also solve the problem of different voltages: High-voltage components (such as IGBTs) are not required during low-voltage starting, only low-voltage switching devices are needed; During high-voltage generating, diodes (low cost, high voltage withstand) are used in the rectifier bridge, and controllable rectification is not required.

[0046] As a further implementation, the three-phase rectifier bridge 8 is respectively electrically connected to the high-voltage power battery 12, the armature winding 11, the filter capacitor 7, and the isolation switch 6.

[0047] In this embodiment, the three-phase rectifier bridge is used to rectify the alternating current of the armature winding into high-voltage direct current in the power generation mode, and directly charge the high-voltage power battery. Mature high-voltage diodes in the industry (such as 1200V Si diodes) can be used, and the cost is much lower than that of IGBT; the complex PWM control is omitted, and the system reliability is improved.

[0048] In this embodiment, the filter capacitor is used to smooth the rectified DC voltage and reduce the impact of high-frequency ripples on the high-voltage battery.

[0049] As a further implementation, the three-phase drive bridge 5 is electrically connected to the P1, P2, and P3 interfaces of the starting and generating control unit 1, and is also electrically connected to the low-voltage battery 4.

[0050] In this embodiment, the three-phase drive bridge 5 is used to perform power conversion on the direct current of the low-voltage battery in the starting mode and drive the motor to rotate. Since the starting voltage is low (such as 24V), low-breakdown-voltage (such as 60V) and low-cost switching tubes can be selected.

[0051] As a further implementation, the isolation switch 6 can be any one of an electromagnetic switch and an electronic switch. The electromagnetic switch includes but is not limited to a DC relay, a DC contactor, and a solid-state relay. The electronic switch includes but is not limited to IGBT and MOSFET.

[0052] MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) is a commonly used voltage-controlled semiconductor switching device, which is widely used in power switching, signal amplification, motor drive and other fields of electronic circuits.

[0053] IGBT (Insulated Gate Bipolar Transistor) is a composite power semiconductor device that combines the high input impedance of MOSFET and the low conduction loss of BJT (Bipolar Junction Transistor). It is widely used in high-voltage and high-current power electronic systems, such as frequency converters, inverters, and electric vehicle drives.

[0054] As a further implementation, the three-phase rectifier bridge 8 can be any one or more of a rectifier diode, a silicon carbide diode, and a Schottky diode.

[0055] As a further embodiment, the excitation drive 9 is any one of an IGBT and a MOSFET. In this embodiment, taking the MOSFET as an example, the F port of the starting and generating control unit 1 is electrically connected to the gate of the excitation drive 9, the source of the excitation drive 9 is electrically connected to the excitation winding 10, and the drain of the excitation drive 9 is respectively electrically connected to the U port of the starting and generating control unit 1, the three-phase rectifier bridge 8, and the positive electrode of the high-voltage power battery 12.

[0056] As a further embodiment, the three-phase drive bridge 5 is composed of MOSFETs.

[0057] In this embodiment, as Figure 1 shown, the three-phase rectifier bridge 8 has six groups of diodes, simply referred to as D1 - D6. Among them, D1 and D4 are in series, D3 and D6 are in series, D5 and D2 are in series. The cathodes of D1, D3, and D5 are all connected to the positive electrode of the high-voltage power battery, and the anodes are respectively connected to the cathodes of D4, D6, and D2. The anodes of D4, D6, and D2 are all connected to the negative electrode of the power battery; the armature winding 11 has three-phase windings A, B, and C, and the three-phase windings are respectively connected between D1 and D4, between D3 and D6, and between D5 and D2; at the same time, one end of the isolation switch 6 is respectively connected between D1 and D4, between D3 and D6, and between D5 and D2 of the three-phase rectifier bridge 8 to realize the electrical connection between the isolation switch 6, the armature winding 11, and the three-phase rectifier bridge 8.

[0058] In this embodiment, the filter capacitor 7 is connected in parallel between the cathode of D5 and the anode of D2.

[0059] In this embodiment, the three-phase drive bridge 5 has six groups of MOSFETs, simply referred to as T1 - T6 tubes. Among them, the gates of the T1 - T6 tubes are all electrically connected to the starting and generating control unit 1. T1, T4, and the sampling resistor R1 are in series, T3, T6, and the sampling resistor R2 are in series, T5, T2, and the sampling resistor R3 are in series. The drains of T1, T3, and T5 are all connected to the positive electrode of the low-voltage battery 4, and the sources are respectively connected to the drains of T4, T6, and T2 correspondingly. The sources of T4, T6, and T2 are respectively electrically connected to the corresponding sampling resistors R1, R2, and R3. The other ends of the sampling resistors R1, R2, and R3 are all connected to the negative electrode of the low-voltage battery 4; the P1 interface, P2 interface, and P3 interface of the starting and generating control unit 1 are respectively connected between T4 and the sampling resistor R1, between T6 and the sampling resistor R2, and between T2 and the sampling resistor R3.

[0060] In this embodiment, the other end of the isolation switch 6 is respectively connected between T1 and T4, between T3 and T6, and between T5 and T2 of the three-phase drive bridge 5, thereby realizing the electrical connection between the isolation switch 6 and the three-phase drive bridge 5.

[0061] The system given in this embodiment has a dual-mode operation function. In the starting mode, the doubly salient electro-magnetic motor is used as a motor to convert the electrical energy of the low-voltage battery into mechanical energy (such as starting an internal combustion engine). In the power generation mode, the doubly salient electro-magnetic motor is used as a generator to convert mechanical energy into electrical energy to charge or supply the high-voltage power battery.

[0062] The system given in this embodiment can be compatible with different voltage levels, that is, "different voltages". The automatic switching between low-voltage starting (such as 24V) and high-voltage power generation (such as 540V) is realized through a three-phase rectifier bridge and a disconnector to meet different load requirements.

[0063] In the system, the three-phase rectifier bridge rectifies the alternating current of the armature winding into high-voltage direct current to charge the power battery in the power generation mode. The three-phase drive bridge performs power conversion on the low-voltage direct current to drive the motor to rotate in the starting mode. The disconnector is used to physically isolate the starting and power generation circuits to prevent the low-voltage circuit from being damaged by high-voltage backflow. The excitation drive is used to independently control the current of the excitation winding to achieve precise regulation of the power generation voltage (such as voltage stabilization when the load changes suddenly).

[0064] In summary, this solution avoids the costs and complexities of high-voltage withstand IGBTs and controlled rectifiers through the combination of a disconnector + diode rectifier bridge + low-voltage inverter bridge. The uncontrolled rectification (diode) is adopted in the power generation mode, without switching losses and the risk of drive failure; the physical isolation by the disconnector completely eliminates the mutual series connection of high and low voltages; it is a low-voltage open-loop control (V / f control) during starting, and only the excitation current needs to be adjusted during power generation (without PWM rectification).

[0065] In this embodiment, the disconnector is a DC contactor. The static contact is electrically connected to the armature winding and the three rectifier bridges, the moving contact is electrically connected to the three-phase drive bridge, and the DC contactor coil is electrically connected to the starting and power generation control unit.

[0066] After the key switch is turned on, the starting and power generation control unit is powered on and standby, waiting for instructions. When the starting instruction is obtained through the communication interface, the starting and power generation control unit outputs a voltage signal to control the DC contactor coil, so that the moving contact of the contactor closes, connecting the three-phase drive bridge and the armature winding.

[0067] According to the different rotor positions of the doubly salient electro-magnetic motor, the starting and power generation control unit obtains the corresponding inductance differences of the three-phase armature windings, controls the upper and lower arm switches in the three-phase drive bridge, injects pulse voltages with the same time and amplitude into the three-phase windings respectively, and determines the rotor position by collecting the current magnitudes of the three-phase armature windings within the same time through the P1, P2, and P3 interfaces, determines the energized phase of the starting power-on in the counterclockwise rotation, energizes it, outputs torque to drive the engine to the ignition speed, and realizes sensorless starting.

[0068] In the starting mode, when the three-phase armature windings are connected in a Y shape in this embodiment, the flow direction of the low-voltage drive current to the A-phase winding and the B-phase winding is illustrated by way of example.

[0069] As Figure 1 shown, when the starting and generating control unit controls T1 and T6 to conduct simultaneously, the current flows from the positive terminal of the low-voltage battery, through the T1 tube of the three-phase drive bridge, then through the closed contact of the disconnector, to the A end to the X end of the A-phase armature winding, then through the Y end to the B end of the B-phase winding, through the closed contact of the disconnector, through the T6 tube, and then through the sampling resistor R2 to the negative terminal of the low-voltage battery, forming a loop; during this period, it passes through the nodes of the three-phase rectifier bridges D1 and D4, D3 and D6, where the cathodes of D1 and D3 are connected to the positive terminal of the high-voltage power battery, and the anodes of D4 and D6 are connected to the negative terminal of the power battery. Since the diode has the characteristic of unidirectional conduction, that is, it conducts when a forward voltage is applied from the anode to the cathode of the diode and blocks when a reverse voltage is applied. The cathode voltages of D1 and D3 connected to the positive terminal of the high-voltage power battery are greater than the anode voltages of D1 and D3 applied by the low-voltage drive. At the same time, the anode voltages of D1 and D3 (which are also the cathode voltages of D4 and D6) are greater than the voltage of the negative terminal of the power battery. D1, D3 and D4, D6 show a blocking characteristic, and high voltage cannot flow back into the A-phase armature winding and the B-phase armature winding, achieving high-voltage and low-voltage electrical isolation.

[0070] When the engine is dragged to the ignition speed, the starting and generating control unit controls the DC contactor coil to power off, so that the moving contact of the contactor disconnects, and the three-phase drive bridge is disconnected from the armature winding and the three-phase rectifier bridge, completing the counterclockwise start.

[0071] After the counterclockwise start is completed, if a power generation command is received, the starting and generating control unit controls the excitation drive by outputting a PWM signal with an adjustable duty cycle through the F interface based on the SOC of the high-voltage power battery determined through the U interface and the speed determined through the P interface, so as to adjust the working voltage of the excitation winding and control the magnitude of the excitation current. The induced electromotive force of the armature winding is rectified by the three-phase rectifier bridge to output a controllable DC voltage and current.

[0072] In this embodiment, when the disconnector is disconnected, the electrical connection between the three-phase armature winding and the three-phase drive bridge is disconnected, achieving high-voltage and low-voltage electrical isolation. The three-phase armature winding is electrically connected to the three-phase rectifier bridge, and one of the windings is connected to the P terminal of the starting and generating control unit. After the starting and generating control unit receives a power generation command, it controls the excitation drive through the U terminal and the F terminal to provide an excitation current. The three-phase armature winding induces an electromotive force, which is rectified by the three-phase rectifier bridge to output high-voltage direct current.

[0073] The flow direction of the current output by the A-phase winding and the B-phase winding when the three-phase armature windings are connected in a Y shape is illustrated by way of example.

[0074] The three-phase electromotive forces induced in the three-phase windings have a phase difference. When the potential of one-phase electromotive force is at its maximum, the potential of another-phase electromotive force is at its minimum. For example, when the induced electromotive force of phase A winding is positive and greater than the terminal voltage of the high-voltage power battery, D1 conducts forward. At the same time, the induced electromotive force of phase B winding is negative and less than the negative voltage of the high-voltage power battery, D6 conducts forward. The current flows from terminal A of phase A winding through D1 to the positive pole of the high-voltage power battery, passes through the inside of the battery to the negative pole of the battery, and then from the negative pole of the battery through D6 to terminal B of phase B winding to terminal Y, that is, returns from terminal X of phase A winding to terminal A, forming a loop to charge the high-voltage power battery. During this period, the current flows through the nodes of D1, D4 and D3, D6 and the static contacts of the disconnector. Because the moving contact of the disconnector is disconnected, the high voltage will not flow into the low-voltage drive axle, realizing the electrical isolation between high voltage and low voltage.

[0075] To sum up, this solution decouples the high-voltage and low-voltage circuits through the disconnector, simplifies the complex, realizes that "low-voltage components do low-voltage work, and high-voltage components do high-voltage work", and realizes different-voltage design, solving the compatibility problem of starting (low voltage) and generating electricity (high voltage) at low cost. At the same time, it avoids the pain points of high-voltage withstand IGBT and complex controllable rectification.

[0076] The electric-excited doubly salient different-voltage DC starting and generating system has low cost and high reliability, especially used in the field of range extenders for electric vehicles. Since the starting time of the range extender for electric vehicles is less than 2 seconds, the working time of the low-voltage three-phase drive axle of this solution is short during starting and dragging the engine, with less heat loss, high overall efficiency, simple power generation control, and high economic and social benefits.

[0077] Embodiment 2: As Figure 2 shown, taking the counterclockwise rotation as the starting direction, an electric-excited doubly salient different-voltage DC starting and generating system includes: an electric-excited doubly salient motor and a starting and generating controller. The electric-excited doubly salient motor internally contains an excitation winding 10 and an armature winding 11 sleeved on the stator teeth; the starting and generating controller internally contains a three-phase rectifier bridge 8, an excitation driver 9, a disconnector 6, a starting and generating control unit 1, a three-phase drive axle 5, and a filter capacitor 7.

[0078] The system structure of this embodiment is the same as that of Embodiment 1. The disconnector in it uses 3 silicon carbide MOSFET tubes K1-K3. The sources of the 3 MOSFET tubes are electrically connected to the armature winding 11 and the three-phase rectifier bridge 8, the drains are electrically connected to the three-phase drive axle 5, and the gates are electrically connected to the starting and generating control unit 1.

[0079] When the ignition key switch is turned on, the starting and generating control unit gets powered and stands by waiting for an instruction. When the starting instruction is obtained through the communication interface, the starting and generating control unit outputs a signal to control the 3 MOSFET tubes to conduct simultaneously, connecting the three-phase drive axle and the armature winding.

[0080] According to different rotor positions, the inductance of the three-phase armature winding is different. The starting and generating control unit controls the switches of the upper and lower arms of the three-phase drive bridge, injects pulse voltages with the same time and amplitude into the three-phase armature winding respectively, collects the current magnitudes of the three-phase armature winding within the same time through interfaces P1, P2, and P3, determines the rotor position based on different currents, determines the energized phase for counterclockwise rotation starting to conduct electricity, outputs torque to drive the engine to the ignition speed, and realizes sensorless starting.

[0081] When dragging the engine to the ignition speed, the starting and generating control unit controls the three MOSFETs to cut off simultaneously, disconnecting the three-phase drive bridge from the armature winding and the three-phase rectifier bridge, and completing counterclockwise starting.

[0082] After completing counterclockwise starting, if a power generation command is received, the starting and generating control unit determines the SOC of the power battery through interface U and the speed determined by interface P, controls the F interface to output a PWM signal with adjustable duty cycle to control the excitation drive, adjusts the working voltage of the excitation winding, controls the magnitude of the excitation current, realizes sensorless current control, and the induced electromotive force of the three-phase armature winding is rectified by the three-phase rectifier bridge to output adjustable DC voltage and current.

[0083] Embodiment 3: A control method for an electric-excited doubly salient variable-voltage DC starting and generating system includes the following steps: When the starting and generating control unit receives a starting signal from the communication interface, the isolating switch closes, and an electrical connection is established between the three-phase drive bridge, the armature winding, and the three-phase rectifier bridge. The switch signal of the three-phase drive bridge from the low-voltage battery terminal is electrically isolated from the high-voltage power battery terminal through the diodes in the three-phase rectifier bridge and enters the armature winding; The starting and generating control unit calculates the rotor position, controls the three-phase drive bridge to perform switch commutation on the armature winding, outputs torque to drive the engine speed to the ignition starting speed, and after completion of starting, the isolating switch disconnects the electrical connection between the three-phase drive bridge, the armature winding, and the three-phase rectifier bridge.

[0084] After completion of starting, if a power generation command is received, the starting and generating control unit determines the SOC of the high-voltage power battery determined by interface U and the speed determined by interface P, controls the F interface to output a PWM signal with adjustable duty cycle to control the excitation drive, so as to adjust the working voltage of the excitation winding and control the magnitude of the excitation current, and the induced electromotive force of the armature winding is rectified by the three-phase rectifier bridge to output adjustable DC voltage and current.

[0085] As a further embodiment, the starting and generating control unit controls the adjustable voltage applied to the exciting winding through the F interface, and can obtain an adjustable exciting current without a current sensor. When the doubly salient electro-magnetic motor starts, the three-phase windings are energized in sequence using the standard switching angle for chopped current limiting starting.

[0086] As a further embodiment, based on the inductance differences of the three-phase armature windings caused by different rotor positions, the starting and generating control unit controls the upper and lower arm switches in the three-phase drive bridge to inject pulse voltages of the same time and amplitude into the three-phase windings respectively, and determines the rotor position by collecting the current magnitudes of the three-phase armature windings within the same time through the P1, P2, and P3 interfaces, thus realizing sensorless starting.

[0087] As a further embodiment, when the starting and generating control unit receives a generating command and the isolation switch disconnects the electrical connection between the three-phase drive bridge connected to the low-voltage battery and the armature winding, the starting and generating control unit obtains the battery voltage SOC through interface U, and outputs a PWM signal with adjustable duty ratio through interface F to control the exciting drive. By adjusting the working voltage of the exciting winding, an adjustable exciting current is provided. After the induced electromotive forces of the three-phase armature windings are rectified by the three-phase rectifier bridge, a controllable DC voltage and current can be output. As a further embodiment, the starting and generating control unit collects the induced electromotive force of one phase in the armature winding through interface P, calculates the instantaneous speed based on the phase electromotive force period, and outputs a PWM signal with controllable duty ratio through interface F according to the speed to control the exciting drive, providing an adjustable exciting current. Without a speed sensor, the induced electromotive force of the armature winding is rectified by the three-phase rectifier bridge, and a controllable DC voltage and current can be output.

[0088] Through the isolation switch, the problem of different starting power supply voltages and generating output voltages is solved at a lower cost. At the same time, the problems that the existing integrated starting and generating controller needs to select high-voltage withstand IGBT switch tubes when generating high voltages, increasing the cost of the controller and the complexity of control when using IGBT switch tubes for controllable rectification are solved. It has low cost and high reliability, especially used in the field of range extenders for electric vehicles. Since the starting time of the range extender for electric vehicles is less than 2 seconds, the working time of driving the engine during starting is short, the heat loss is small, the overall efficiency is high, and the generating control is simple, with high economic and social benefits.

[0089] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An electric-excited doubly salient variable-voltage DC starting and generating system, characterized in that It includes an electrically excited doubly salient motor and a start - generator controller. The electrically excited doubly salient motor has an exciting winding and an armature winding sleeved on the stator teeth; the start - generator controller has a start - generator control unit, and the start - generator control unit is electrically connected to a three - phase rectifier bridge, an exciting driver, a three - phase drive bridge and a disconnector respectively; the exciting driver is electrically connected to the exciting winding; one end of the disconnector is electrically connected to the armature winding and the three - phase rectifier bridge respectively, and the other end is electrically connected to the three - phase drive bridge.

2. The electro-excited doubly salient variable-voltage DC starting and generating system according to claim 1, characterized in that, The start - generator control unit is connected to a low - voltage battery through a key switch and is powered by the low - voltage battery after the key switch is turned on; the start - generator control unit is connected to an external communication interface for receiving instructions.

3. A doubly salient electro-excited variable-voltage DC starting / generating system according to claim 1, characterized in that, The start - generator control unit is electrically connected to the armature winding through interface P, electrically connected to the exciting driver through interface F, and electrically connected to the exciting driver, the three - phase rectifier bridge, a filter capacitor and a high - voltage power battery through interface U.

4. The electro-excited doubly salient variable-voltage DC starting and generating system according to claim 1, characterized in that, The three - phase rectifier bridge is electrically connected to the high - voltage power battery, the armature winding, the filter capacitor and the disconnector respectively.

5. A doubly salient electro-excited variable-voltage DC starting / generating system according to claim 1, characterized in that, The exciting driver is electrically connected to the exciting winding and is also electrically connected to interface F and interface U of the start - generator control unit for regulating the DC exciting current.

6. The electro-excited doubly salient variable-voltage DC starting / generating system according to claim 1, characterized in that The three - phase drive bridge is electrically connected to interfaces P1, P2 and P3 of the start - generator control unit and the low - voltage battery respectively.

7. A doubly salient electro-excited variable-voltage DC starting and generating system according to claim 1, wherein The disconnector is an electromagnetic switch or an electronic switch. The electromagnetic switch includes at least a DC relay, a DC contactor and a solid - state relay, and the electronic switch includes at least an IGBT and a MOSFET.

8. A doubly salient electro-magnetic variable-voltage DC starting / generating system according to claim 1, wherein The three - phase rectifier bridge is any one or more of a rectifier diode, a silicon carbide diode and a Schottky diode.

9. The electro-excited doubly salient variable-voltage DC starting / generating system according to claim 1, wherein The power switch device of the exciting driver is any one of an IGBT or a MOSFET; all the switch devices of the three - phase drive bridge are MOSFETs.

10. A control method for an electric-excited double salient variable-voltage DC starting / generating system as described in any one of claims 1-9, characterized in that, It includes the following steps: When the start - generator control unit receives a start signal from the communication interface, the disconnector closes, and the electrical connection between the three - phase drive bridge and the armature winding and the three - phase rectifier bridge is established. The switch signal of the three - phase drive bridge from the low - voltage battery terminal is electrically isolated by the diodes in the three - phase rectifier bridge and enters the armature winding. The start - generator control unit controls the three - phase drive bridge to perform switch commutation on the armature winding by calculating the rotor position, and outputs torque to drive the engine speed to the ignition starting speed; when starting is completed, the disconnector disconnects the electrical connection between the three - phase drive bridge and the armature winding and the three - phase rectifier bridge. After successful starting, if the start - generator control unit receives a power - generation instruction, the start - generator control unit determines the SOC of the high - voltage power battery through interface U and the speed through interface P, and controls interface F to output a PWM signal with adjustable duty cycle to control the exciting driver, regulating the working voltage of the exciting winding to control the magnitude of the exciting current. The induced electromotive force of the armature winding is rectified by the three - phase rectifier bridge to output a controllable DC voltage and current.

Images