Method for switching between a full-winding mode and a half-winding mode in a three-phase machine

Abstract

A method for controlling switching between a full-winding control mode and a half-winding control mode for a symmetrical winding configuration of a multi-phase electric machine (10), the machine (10) including a stator (18) and a rotor (14), split stator windings for each phase of the machine (10), each stator winding (24) having a first winding portion and a second winding portion, an inverter circuit (50) including a pair of inverter switches (56) for each phase of the machine (10), the pair of inverter switches (56) for each phase being electrically coupled to the first and second winding portions for that phase in the stator (18) and a plurality of switching arrangements for switching between the full-winding mode and the half-winding mode,wherein each switch assembly is electrically coupled to the pair of inverter switches (56) and the first and second winding sections for a particular phase, and wherein each switch assembly includes a first AC switching device (90) and a second AC switching device (90), the method comprising: , identifying the motor speed and torque command signals for the machine; determining whether the motor speed and torque command signals require full winding mode or half winding mode; determining whether the winding control mode of the machine (10) transitions from the half-winding mode to the full-winding mode if the motor speed and torque command signals require the full-winding mode, and determining whether the winding control mode transitions from the full-winding mode to the half-winding mode if the motor speed and torque command signals require the half-winding mode; providing switching control commands for the plurality of switching arrangements for a direct-axis current, a quadrature-axis current, and the current loop gains for full stator windings, provided that the motor speed and torque command signals require the full-winding mode and the winding mode does not transition from the half-winding mode to the full-winding mode, or providing switching control commands for the plurality of switching arrangements for the direct-axis current, the quadrature-axis current, and the current loop gain for half-stator windings, provided that the motor speed and torque command signals require the half-winding mode and the winding mode does not transition from the full-winding mode to the half-winding mode; setting the direct-axis and quadrature-axis current to zero if the motor speed and torque command signals require the full-winding mode or the half-winding mode and it is determined that the winding mode is transitioning from the half-winding mode to the full-winding mode or from the full-winding mode to the half-winding mode; waiting for a phase current in each of the stator windings (24) to be less than a predetermined minimum current after the direct axis and quadrature axis currents have been set to zero; deactivating the inverter circuit switching signals and the half-winding mode switching signals transmitted to the AC switching devices (90) for the full-winding mode, or deactivating the inverter circuit switching signals and the full-winding mode switching signals transmitted to the AC switching devices (90) for the half-winding mode after the direct-axis and quadrature-axis currents are set to zero; waiting for a predetermined delay time after the inverter circuit switching signals and the half-winding mode switching signals or the full-winding mode switching signals are deactivated; setting the direct-axis current, the quadrature-axis current and the current loop gain to predetermined values ​​for the full-winding mode or the half-winding mode after the delay time has elapsed; activating the inverter switching signals and the full-winding mode switching signals transmitted to the AC switching devices (90) for the full-winding mode, or activating the inverter switching signals and the half-winding mode switching signals transmitted to the AC switching devices (90) for the half-winding mode; and providing the switching control commands for the plurality of switching arrangements for the direct axis current, the quadrature axis current, and the current loop gains for the full stator windings and the half stator windings, respectively.

Description

BACKGROUND OF THE INVENTIONField of the invention

[0001] This invention relates generally to a method for switching between a full winding control mode and a half winding control mode for an AC machine, and more particularly to a method for switching between a full winding control mode and a half winding control mode for a three-phase permanent magnet (PM) AC electric machine with split stator windings to reduce back EMF and increase machine torque and power at higher machine speeds. Explanation of the state of the art

[0002] For automotive powertrains such as hybrid vehicles, electric vehicles, fuel cell vehicles, etc., and for power generation applications, an electric machine with a wide speed range is essential. To maximize its torque / ampere ratio, an electric machine is typically designed to have the highest possible induced voltage-to-speed ratio. However, because the induced voltage is proportional, especially as the machine speed increases, the back-emf generated by the machine also increases with increasing machine speed until it reaches the intermediate circuit voltage, generally a battery voltage, resulting in a loss of the emf available to drive current to the motor, thereby limiting the machine speed.

[0003] It is known in the art that the stator windings for each phase of an electric machine must be separated into two split windings to reduce back EMF at high machine speeds. Switches are provided and controlled so that the split windings for each phase are electrically connected in series for low machine speeds and in parallel when the machine speed reaches the point where back EMF reduces machine torque. By providing twice the number of windings in the stator and the switches required to switch between an electrical series configuration and a parallel configuration, this winding reconfiguration solution increases the number of required AC switches to nine, while the total number for a three-phase machine is ten.Furthermore, there is the potential for currents to circulate in the parallel configuration due to coil EMF mismatches. Furthermore, the coils must be located in the same stator slot for parallel operation, while the lower coil inductance in parallel operation may require higher switching frequencies to reduce current ripple.

[0004] US Patent Application No. US 2014 / 0 239 876 A1 to Hao et al., published on August 28, 2014, assigned to the assignee of this application, discloses an electric drive system for a three-phase PM electric machine, wherein each phase of the machine includes a stator winding separated into a first winding section and a second winding section, and two switches in an inverter electrically coupled to the winding sections. The drive system includes a switch assembly for each phase electrically coupled to the inverter switches and the first and second winding sections, the switch assembly including at least two switching states.A first switching state of the switch arrangement electrically couples the first winding section and the second winding section in series with the inverter switches, while a second switching state, which is electrically coupled with the second winding section to the inverter switches, electrically disconnects the first winding section from the inverter switch.

[0005] DE 10 2012 209 080 A1 relates to a stator phase circuit for an electrical machine comprising a phase winding circuit comprising a plurality of serially coupled partial winding circuits, wherein each partial winding circuit comprises a respective partial winding coupled in parallel via a respective first controllable switch.

[0006] WO 2013 / 041202 A2 relates to an electric motor, in particular a pole-changing motor, and to a method for operating an electric motor and electric motor, wherein the stator winding is constructed from phases, in particular from three phases (U, V, W), wherein each phase has coil groups, in particular four coil groups, wherein each coil group is constructed from coils, in particular three concentrically arranged coils, wherein the connections of each coil group are led to an interconnection unit, wherein the interconnection produced by the interconnection unit has a number of coil groups of a respective phase arranged in parallel, wherein different interconnections can be produced by means of the interconnection unit, so that the number can be changed, in particular during operation of the electric motor.

[0007] EP 2 544 361 A2 relates to an inverter according to one embodiment comprising a constant power controller. The constant power controller calculates and outputs, when a value of a voltage reference for an AC motor exceeds a predetermined threshold, a d-axis current reference correction value based on the value of the voltage reference and the predetermined threshold. Furthermore, the constant power controller generates the d-axis current reference correction value using a constant power model determined by a torque reference or a speed reference and a supplied DC voltage at an output switching timing determined based on a winding switching signal, and outputs the d-axis current reference correction value for a predetermined time. SUMMARY OF THE INVENTION

[0008] The present invention discloses and describes a method for controlling switching between a full winding control mode and a half winding control mode for a symmetrical winding configuration of a multi-phase electric machine.The machine includes a stator and a rotor, split stator windings for each phase of the machine, each stator winding including a first winding portion and a second winding portion, an inverter including a pair of inverter switches for each phase of the machine, the pair of inverter switches for each phase being electrically coupled to the first and second winding portions for that phase in the stator, and a plurality of switch assemblies for switching between the full winding mode and the half winding mode, each switch assembly being electrically coupled to the pair of inverter switches and the first and second winding portions for a particular phase, and each switch assembly including a first AC switching device and a second AC switching device.The method includes identifying motor speed and torque command signals for the machine and determining whether the motor speed and torque command signals require the full winding mode or the half winding mode. The method also includes determining whether the winding control mode of the machine transitions from the half winding mode to the full winding mode when the motor speed and torque command signals require the full winding mode, and determining whether the winding control mode transitions from the full winding mode to the half winding mode when the motor speed and torque command signals require the half winding mode.The method provides switching control commands for the plurality of switching arrangements for a direct-axis current, a quadrature-axis current, and current loop gains for full stator windings when the motor speed and torque command signals require the full-winding mode and the winding mode does not transition from the half-winding mode to the full-winding mode, or provides switching control commands for the plurality of switching arrangements for the direct-axis current, the quadrature-axis current, and the current loop gain for half stator windings when the motor speed and torque command signals require the half-winding mode and the winding mode does not transition from the full-winding mode to the half-winding mode.The method sets the direct-axis current and the quadrature-axis current to zero when the motor speed and torque command signals require the full-winding mode or the half-winding mode and it is determined that the winding control mode is transitioning from the half-winding mode to the full-winding mode or from the full-winding mode to the half-winding mode.The method waits for a phase current in each of the stator windings to be less than a predetermined minimum current after the direct-axis current and the quadrature-axis current are set to zero, and deactivates inverter switching signals and half-winding mode switching signals transmitted to the full-winding mode AC switching devices, or the inverter switching signals and full-winding mode switching signals transmitted to the half-winding mode AC switching devices after the direct-axis current and the quadrature-axis current are set to zero. The method waits for a predetermined delay time after the inverter switching signals and the half-winding mode switching signals or the full-winding mode switching signals are deactivated.The method sets the direct-axis current, the quadrature-axis current, and the current loop gain for the full-winding mode or the half-winding mode to predetermined values ​​after the delay time has elapsed, enables the inverter switching signals and the full-winding mode to be transmitted to the AC switching devices for the full-winding mode, or the inverter switching signals and the half-wave switching signals to be transmitted to the AC switching devices for the half-winding mode, and provides the switching control commands for the plurality of switching arrangements for the direct-axis current, the quadrature-axis current, and the current loop gain for the full-stator windings or for the half-stator windings.

[0009] Further features of the present invention will become apparent from the following description and the appended claims in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 shows a broken-away end view of a PM electric machine having a stator and a rotor; Fig. Figure 2 shows a schematic block diagram of a six-lead AC switching drive system for a PM electric machine using anti-parallel SCR AC switches; Fig. Figure 3 shows a schematic block diagram of a four-wire, nine-lead AC switching drive system for a PM electric machine using anti-parallel SCR AC switching devices; Fig. Figure 4 shows a schematic diagram of an SCR-RC suppressor circuit; Fig. 5 shows a schematic block diagram of an SCR drive system for the Fig. 2 power switches shown; Fig. 6 shows a schematic block diagram of an SCR drive system for the Fig. 3 power switch shown; Fig. Figure 7 shows a schematic diagram of an anti-series IGBT AC switching device used in the Fig. 2 and Fig. 3 drive systems shown; Fig. Figure 8 shows a schematic diagram of an anti-parallel RB-IGBT AC switching device used in the Fig. 2 and Fig. 3 drive systems shown; Fig. Figure 9 shows a flowchart illustrating a control scheme for switching between a full winding mode and a half winding mode for a symmetric winding reconfiguration of a three-phase PM machine using the SCR drive systems. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0010] The following explanation of embodiments of the invention directed to a method for switching between a full-winding control mode and a half-winding control mode in a three-phase PM electric machine is merely exemplary and is in no way intended to limit the invention or its applications or uses in any way. For example, the inventive method finds particular application in a three-phase PM machine on a vehicle. However, as those skilled in the art will recognize, the inventive method also finds application in other machines.

[0011] Fig. 1 shows a broken-away end view of a conventional PM three-phase electric machine 10. The electric machine 10 includes a central shaft 12 surrounded by and fixed to a cylindrical rotor 14. The rotor 14 includes a plurality of permanent magnets 16 disposed around an outer periphery of the rotor 14. The machine 10 also includes a cylindrical stator 18 having stator teeth 20 defining slots 22 therebetween, with stator windings 24 wound around the teeth 20 through the slots 22. An air gap 26 separates the rotor 14 from the stator 18 and allows it to rotate relative thereto.

[0012] As known to those skilled in the art, an alternating current is supplied to the stator windings 24 in the correct phase so that the magnetic field created by the current flowing through the windings 24 interacts with the magnetic field of the permanent magnets 16 in a manner that causes the rotor 14 to rotate relative to the stator 18 and thus causes the shaft 12 to rotate and perform physical work. A flux path around the windings 24 passes through the rotor 14, the permanent magnet 16, the air gap 26, and the stator 18 to form a closed loop path and connect the stator windings 24. The induced voltage of the stator 18 is proportional to the total flux connecting the stator windings 24. The interaction of the magnetic flux between the permanent magnet 16 and the current flow in the windings 24 creates the torque that drives the machine 10.

[0013] Fig. Figure 2 shows a schematic block diagram of a drive system 30 for a three-phase PM machine, such as machine 10, illustrating windings for a stator 32 of the machine. The windings include split stator windings with winding sections 34 and 36 for the first machine phase, winding sections 38 and 40 for the second machine phase, and winding sections 42 and 44 for the third machine phase.

[0014] The drive system 30 includes an inverter / rectifier circuit 50 having a plurality of MOSFET or IGBT switches that are selectively turned on and off to provide DC and AC inversion and rectification between a vehicle battery (not shown) coupled to nodes 52 and 54 and the winding sections 34-44 in the stator 32. In particular, the circuit 50 includes switches 56 and 58 for controlling the first phase winding sections 34 and 36, switches 60 and 62 for controlling the second phase winding sections 38 and 40, and switches 64 and 66 for controlling the third phase winding sections 42 and 44. The circuit 50 converts the DC power from the battery to an AC power when the machine is operating as a motor, for example, to start the vehicle.Circuit 50 also includes a plurality of diodes 68 that rectify the alternating current generated by winding sections 34-44 to a direct current to charge the battery. Switches 56-66 are switched by a controller 80 on six lines 70, with controller 80 receiving a torque command signal on line 82 and a machine speed signal on line 84 to provide the desired AC / DC conversion in a manner well known to those skilled in the art.

[0015] The drive system 30 also includes a silicon controlled rectifier (SCR) switching system 90 that switches the current signals from the inverter circuit 50 so that at low machine speeds, all winding sections 34-44 are electrically coupled to the inverter 50, and only winding sections 36, 40, and 44 are electrically coupled to the circuit 50 at high machine speeds. As explained above, by reducing the number of stator windings at high machine speeds, the back EMF of the machine is reduced by reducing the magnetic flux when the back EMF is significant enough to reduce the machine speed by limiting the current flow through the stator windings in a manner similar to that disclosed in the above-mentioned '876 application.

[0016] To provide this winding reconfiguration operation, the switching system 90 includes a switching circuit 92 having a first switch assembly 120 for switching the first phase winding sections 34 and 36, a second switch assembly 122 for switching the second phase winding sections 38 and 40, and a third switch assembly 124 for switching the third phase winding sections 42 and 44. The first switch assembly 120 includes AC switching devices 94 and 96 coupled to nodes A2 and A1, respectively, for switching the first phase winding sections 34 and 36 between the full-winding mode and the half-winding mode. The second switch assembly 122 includes AC switching devices 98 and 100 coupled to nodes B2 and B1 for switching the second phase winding sections 38 and 40 between the full-winding mode and the half-winding mode.The third switch assembly 124 includes AC switching devices 102 and 104 coupled to nodes C1 and C2, respectively, for switching the third phase winding sections 42 and 44 between the full-winding mode and the half-winding mode. Each of the switching devices 94, 96, 98, 100, 102, and 104 includes a pair of opposing thyristor switches 106 and 108 that provide a low turn-on voltage, for example, 1-1.5 volts, are very robust, offer high overload capability, and have a switching time of less than 10 ms.

[0017] The switching devices 94, 96, 98, 100, 102, and 104 are controlled by an SCR drive circuit 110, which receives commands from the control unit 80 to switch between the full-winding mode, provided by a command on line 112, and the half-winding mode, provided by a command on line 114. Six control lines 116 are coupled to the switching circuit 92 to switch the switching devices 96, 100, and 102 to the full-winding mode, while six control lines 118 are coupled to the switching circuit 92 to switch the switching devices 94, 98, and 104 to the half-winding mode. A more detailed explanation of how the SCR drive circuit 110 controls the switching devices 94 to 104 to provide the full winding mode and the half winding mode is provided below.

[0018] The winding switching topology illustrated in SCR drive system 90 requires six lines coupled between switching devices 94, 96, 98, 100, 102, and 104, as well as nodes A1, A2, B1, B2, C1, and C2. Alternative embodiments may be used within the scope of the present invention that provide the same type of AC switching between full-winding mode and half-winding mode, but require fewer switches and / or fewer lines.

[0019] Fig. Figure 3 shows a schematic diagram of a drive system 130 with a winding switching topology architecture that uses nine leads and four AC switching devices, wherein like elements of the drive system 30 have the same reference numerals. The control unit 80 and the switching system 90 are shown in FIG. Fig. 3 has been removed. In this embodiment, the six AC switching devices 94, 96, 98, 100, 102, and 104 have been replaced by four AC switching devices, namely an AC switching device 132 electrically coupled between nodes B1 and B2, an AC switching device 134 electrically coupled between nodes C1 and C2, an AC switching device 136 electrically coupled between nodes B2 and B3, and an AC switching device 138 electrically coupled between nodes C2 and C3, as shown. In this embodiment, the number of control lines 116 and 118 is four each. For full-winding mode, the AC switching devices 134 and 138 are turned on, and the AC switching devices 132 and 136 are turned off.This essentially creates a neutral point connecting nodes C1, C2, and C3, with winding sections 34 and 36 through nodes A1, B1, and C1, winding sections 38 and 40 through nodes A2, B2, and C2, and winding sections 42 and 44 through nodes A3, B3, and C3 conducting the current generated by circuit 50. For half-winding mode, AC switching devices 132 and 136 are turned on, and AC switching devices 134 and 138 are turned off.This essentially creates a neutral point connecting nodes B1, B2, and B3, with only winding section 34 through nodes A1 and B1, winding section 38 through nodes A2 and B2, and winding section 42 through nodes A3 and B3 conducting the current generated by circuit 50, and with winding section 36 through nodes B1 and C1, winding section 40 through nodes B2 and C2, and winding section 44 through nodes B3 and C3 being open and not conducting current because switching devices 134 and 138 are off. A more detailed discussion of how SCR drive circuit 110 controls switching devices 132-138 to provide full-winding mode and half-winding mode is set forth below.

[0020] For the embodiments discussed above that use the SCR drive system, circuit elements may be required to measure the voltage change dV / dt and the maximum voltage V max the AC switch to limit. Fig. Figure 4 shows a schematic diagram of an SCR suppressor circuit 170 with an AC switching device 172 of the type described above, as well as circuit elements for limiting the voltage change dV / dt and the maximum voltage V maxThe suppression circuit 170 could be included as part of the respective AC switching devices in the SCR drive circuit in the system 30 or 130. The suppression circuit 170 includes a resistor 174 and a capacitor 176 that define an RC circuit that limits, for example, the voltage change dV / dt to less than 1 kV / µs. In this embodiment, the resistor 174 corresponds to a low-inductance resistor, such as Ls<0.4 µH, while the capacitor 176 is a high-pulse suppression capacitor that causes the voltage change dV / dt to be greater than 2 kV / µs. The voltage change rate dV / dt can be defined by an equivalent circuit as follows: (dVddt)0=R[VL+IRMτ], where R is the resistance of resistor 174, V is the voltage across switch 172, L is the inductance of resistor 174, I RMcorresponds to the current flow through resistor 174 and capacitor 176 and τ is the decay time constant of the SCR reverse recovery current from its peak value of I RM corresponds.

[0021] The suppression circuit 170 also includes a metal oxide varistor (MOV) 178, which provides a voltage clamp to limit the maximum voltage V max and, in one embodiment, limits the SCR voltage below 1.2 kV. Furthermore, the AC switching devices can be mounted on a liquid-cooled cold plate to keep the temperature below 0.01 °C / W.

[0022] Fig. 5 shows a block diagram of an SCR drive system 180, which serves as drive circuit 110 for the Fig. 2 may be used. The system 180 includes a 12-output isolated power supply 182 receiving 12 VDC on line 184 and, in this example, providing 3.3 volts at 1 watt per output for each output line 186. The drive system 180 also includes an isolated drive logic input block 188 receiving twelve inputs, each input turning on one of the thyristor switches 106 and 108 in the switching devices 94-104. More specifically, block 188 receives a group 190 of inputs 192 that control the half-winding mode, each of the inputs 192 turning on a particular one of the thyristor switches 106 and 108 in each of the switching devices 94, 98 and 104, and a group 194 of inputs 196 that control the full-winding mode, each of the inputs 196 turning on one of the thyristor switches 106 and 108 in each of the switches 96, 100 and 102.The signals from the logic input block 188 are then transmitted to a gate drive output block 198 having twelve outputs which control the AC switching devices 94, 96, 98, 100, 102 and 104 to switch between the full winding mode and the half winding mode as described.

[0023] A similar type of SCR drive system can be used for the Fig. 3, which includes the four AC switching devices 132-138. Fig. Figure 6 shows a schematic block diagram of a drive system 200 illustrating this construction, with like elements of the drive system 180 being designated by the same reference numerals. In this embodiment, the power supply 182 is replaced by an isolated eight-output power supply 202, the isolated drive with logic input block 188 is replaced by an isolated drive with logic input block 204, and the gate drive output block 198 is replaced by an eight-output gate drive output block 206. A group 208 of inputs 210 controls the half-winding mode, with each of the inputs 210 turning on one of the thyristor switches 106 or 108 in the switching devices 132 and 136, and a group 212 of inputs 214 controls the full-winding mode, with each of the inputs 214 turning on one of the thyristor switches 106 or 108 in the switching devices 134 and 138.

[0024] In the embodiments discussed above, the switching devices 94, 96, 98, 100, 102, 104, 132, 134, 136, and 138 utilize SCR switches. In alternative embodiments, the thyristor switches 106 and 108 may be replaced with insulated gate bipolar transistor (IGBT) switches. For example, FIG. 7 shows a schematic diagram of an AC switching circuit 150 that includes two anti-series IGBT switches 152 and 154, and two opposing diodes 156 and 158 that are electrically coupled and, as shown, may be used in place of the AC switching devices 94, 96, 98, 100, 102, 104, 132, 134, 136, and 138.

[0025] Alternatively, Fig. 8 is a schematic diagram of an AC switching circuit 160 having two anti-parallel reverse current blocking (RB) IBGT switches 162 and 164 that are electrically coupled and, as shown, may be used in place of the AC switching devices 94, 96, 98, 100, 102, 104, 132, 134, 136, and 138.

[0026] Fig.Figure 9 shows a flowchart 220 illustrating a control scheme for switching between a full-winding control mode and a half-winding control mode for symmetrical winding reconfiguration of a three-phase PM machine using the SCR drive systems described above. At box 222, the algorithm reads the motor speed and torque command signals communicated to the control unit 80 on lines 82 and 84 and identifies any diagnostic fault codes that may affect machine performance and operation. The algorithm then determines whether all possible faults are clear for the inverter circuit 50 at decision diamond 224, and if not, the gate signals sent to the inverter switches 56-66 at box 226 are deactivated and waits for the faults to be reset at box 228.

[0027] If all inverter circuit faults are clear at decision diamond 224, the algorithm reads a winding configuration bit at box 230 to determine whether the motor speed and torque command signals require full-stator winding mode or half-stator winding mode. The winding configuration bit can be set by reading an external digital half-winding input / output line or determined based on the machine's speed and torque error. Once the winding configuration bit is read at box 230, the algorithm determines whether the winding configuration bit is set to full-winding mode at decision diamond 232. If so, a switching control scheme for full-winding mode is provided.Specifically, the algorithm first determines whether the winding configuration has just transitioned from half-winding mode to full-winding mode at decision diamond 234, meaning that the winding control mode was in half-winding mode at the previous sample time. If the winding configuration does not transition from half-winding mode to full-winding mode at decision diamond 234, the algorithm uses switching elements for an appropriate direct-axis current I. d , a quadrature axis current I q and the current loop gains K ip and K ii for full stator windings at Box 236, where the loop gains K ip and K ii for direct and quadrature axis current control and the currents I d and I q from value tables. It is understood in the art that the loop gains K ip and K iiin direct-axis and quadrature-axis current control. The direct-axis current I d , the quadrature axis current I q , as well as the current loop gains K ip and K ii are well-known variables for PID control. The output commands for the currents I d and I q are then sent to box 238 for full winding mode based on the speed and torque commands, while the algorithm returns to box 222 to read the motor speed and torque command signals.

[0028] If the winding configuration transitions from half-winding mode to full-winding mode at decision diamond 234, the algorithm first sets the direct-axis current I d and the quadrature axis current I qto zero and then waits for the phase current in each of the stator windings to be less than a predetermined minimum current ε at box 242. The algorithm also deactivates the inverter switching signals, as well as the half-winding switching signals transmitted at box 244 to the gate terminals of the thyristor switches in the AC switching devices. The algorithm then waits for a predetermined delay time T Verzögerung , which typically corresponds to a calibration number of 1 ms to 10 ms in Box 246, and then sets the direct axis current I in Box 248 d , the quadrature axis current I q , as well as the current loop gains K ip and K iito full-winding mode. The algorithm then activates the inverter switching signals and the full-winding mode switching signals, which are transmitted to the gate terminals of the thyristor switches in the AC switching devices at box 250, and issues the direct-axis and quadrature-axis current commands for full-winding mode at box 238.

[0029] If the full-winding mode winding configuration bit 232 is not set at decision diamond 232, the algorithm determines whether the half-winding mode winding configuration bit is set at decision diamond 252. If not, it returns to box 222 and waits to read the motor speed and torque command.

[0030] If the winding configuration bit is set to half-winding mode at decision diamond 252, the algorithm provides a switching control scheme for half-winding mode. Specifically, the algorithm first determines whether the winding configuration has just transitioned from full-winding mode to half-winding mode at decision diamond 254, meaning that the winding control mode was in full-winding mode at the previous sample time. If the winding mode does not transition from full-winding mode to half-winding mode at decision diamond 254, the algorithm uses switching controls for the direct-axis current I d , the quadrature axis current I q , as well as the current loop gains K ip and K ii for half-stator windings at Box 256, where the current loop gains K ip and K iifor the direct axis and quadrature axis current control of the partial stator windings and the currents I d and I q are provided from value tables. It is understood that K ip and K ii They differ in the direct-axis and quadrature-axis current control of the partial stator winding, but also differ in the gain in the d-axis or q-axis current control of the full stator winding. The output commands for the currents I d and I q are then provided at box 258 for the half-winding mode based on the speed and torque commands, while the algorithm returns to box 222 to read in the motor speed and torque command signals.

[0031] If the winding configuration transitions from full winding mode to half winding mode at decision diamond 254, the algorithm first sets the direct axis current I d and the quadrature axis current I q to zero and then waits for the phase current in each of the stator windings to be less than the predetermined minimum current ε at box 262. The algorithm also deactivates the inverter switching signals and the full-winding switching signals, which are transmitted at box 264 to the gate terminals of the thyristor switches in the AC switching devices. The algorithm then waits for the predetermined delay time T Verzögerung at Box 266 and then sets the direct axis current I at Box 268 d , the quadrature axis current I q , as well as the current loop gains K ip and K iito half-winding mode. The algorithm then activates the inverter switching signals and the half-winding mode switching signals transmitted at box 270 to the gate terminals of the thyristor switches in the AC switching devices, and outputs the direct-axis current command and the quadrature-axis current command for half-winding mode at box 258.

[0032] As is well known to those skilled in the art, the various steps and methods discussed herein to describe the invention may relate to operations utilized by a computer, processor, or other electronic computing device that manipulates and / or alters data using electrical operations. These computers and electronic devices may include various volatile and / or non-volatile memories, including a non-transitory computer-readable medium having an executable program stored thereon, including various codes or executable instructions capable of being executed by computers or processors, wherein the memory and / or computer-readable medium may be any and all forms and types of memory and other computer-readable media.

[0033] The foregoing discussion discloses and describes merely exemplary embodiments of the present invention. Those skilled in the art will readily appreciate from said discussion and the accompanying drawings and claims that various changes, modifications, and variations may be made therein without departing from the spirit and scope of the invention as defined in the following claims.

Claims

[1] A method for controlling switching between a full-winding control mode and a half-winding control mode for a symmetrical winding configuration of a multi-phase electric machine (10), the machine (10) including a stator (18) and a rotor (14), split stator windings for each phase of the machine (10), each stator winding (24) having a first winding portion and a second winding portion, an inverter circuit (50) including a pair of inverter switches (56) for each phase of the machine (10), the pair of inverter switches (56) for each phase being electrically coupled to the first and second winding portions for that phase in the stator (18) and a plurality of switching arrangements for switching between the full-winding mode and the half-winding mode,wherein each switch assembly is electrically coupled to the pair of inverter switches (56) and the first and second winding sections for a particular phase, and wherein each switch assembly includes a first AC switching device (90) and a second AC switching device (90), the method comprising: identifying the motor speed and torque command signals for the machine; determining whether the motor speed and torque command signals require full winding mode or half winding mode; determining whether the winding control mode of the machine (10) transitions from the half-winding mode to the full-winding mode if the motor speed and torque command signals require the full-winding mode, and determining whether the winding control mode transitions from the full-winding mode to the half-winding mode if the motor speed and torque command signals require the half-winding mode; providing switching control commands for the plurality of switching arrangements for a direct-axis current, a quadrature-axis current, and the current loop gains for full stator windings, provided that the motor speed and torque command signals require the full-winding mode and the winding mode does not transition from the half-winding mode to the full-winding mode, or providing switching control commands for the plurality of switching arrangements for the direct-axis current, the quadrature-axis current, and the current loop gain for half-stator windings, provided that the motor speed and torque command signals require the half-winding mode and the winding mode does not transition from the full-winding mode to the half-winding mode; setting the direct-axis and quadrature-axis current to zero if the motor speed and torque command signals require the full-winding mode or the half-winding mode and it is determined that the winding mode is transitioning from the half-winding mode to the full-winding mode or from the full-winding mode to the half-winding mode; waiting for a phase current in each of the stator windings (24) to be less than a predetermined minimum current after the direct axis and quadrature axis currents have been set to zero; deactivating the inverter circuit switching signals and the half-winding mode switching signals transmitted to the AC switching devices (90) for the full-winding mode, or deactivating the inverter circuit switching signals and the full-winding mode switching signals transmitted to the AC switching devices (90) for the half-winding mode after the direct-axis and quadrature-axis currents are set to zero; waiting for a predetermined delay time after the inverter circuit switching signals and the half-winding mode switching signals or the full-winding mode switching signals are deactivated; setting the direct-axis current, the quadrature-axis current and the current loop gain to predetermined values ​​for the full-winding mode or the half-winding mode after the delay time has elapsed; activating the inverter switching signals and the full-winding mode switching signals transmitted to the AC switching devices (90) for the full-winding mode, or activating the inverter switching signals and the half-winding mode switching signals transmitted to the AC switching devices (90) for the half-winding mode; and providing the switching control commands for the plurality of switching arrangements for the direct axis current, the quadrature axis current, and the current loop gains for the full stator windings and the half stator windings, respectively. [2] The method of claim 1, further comprising identifying diagnostic trouble codes or errors that may affect machine performance and operation before determining whether the motor speed and torque command signals require full winding mode or half winding mode, and disabling the switching signals transmitted to the inverter if an error code or error is detected. [3] The method of claim 1, wherein waiting for a predetermined delay time comprises waiting for a time between 1 and 10 ms. [4] The method of claim 1, wherein the electric machine (10) corresponds to a three-phase permanent magnet (PM) AC machine. [5] The method of claim 4, wherein the plurality of switch assemblies corresponds to three switch assemblies and wherein the first AC switching device (90) is electrically coupled to the inverter switches and to both the first and second winding sections to provide the full winding control mode, while the second AC switching device (90) is electrically coupled to the inverter switches and only to the first winding section to provide the half winding control mode for each phase. [6] The method of claim 4, wherein the plurality of switching arrangements corresponds to two switching arrangements, wherein a first switching arrangement includes a first AC switching device (90) electrically coupled between the first and second winding sections of a first winding and first and second winding sections of a second winding, and a second AC switching device (90) electrically coupled to the first winding section of the first winding and the first winding section of the second winding, and a second switching arrangement including a first AC switching device (90) electrically coupled between the first and second winding sections of the second winding, and the first and second winding sections of a third winding and a second AC switching device (90),which is electrically coupled to the first winding section of the second winding and the first winding section of the third winding., [7] The method of claim 1, wherein the electric machine (10) is mounted on a vehicle.

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