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Table 1. Specifications of existing 3-phase BLDC Hub motor

Table 1 Specifications of existing 3-phase BLDC Hub motor

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Figure 1. Assembly of BLDC Hub motor The approach of VARCAS has set off the work of a Six-phase BLDC Hub motor. The existing 3—phase BLDC Hub motor specifications are given in table 1. This BLDC Hub motor is dismantled, and its stator is rewound with the six — phase winding layout, which is determined by author’s presented direct approach. The complete assembly of the Hub motor is shown in figure 1.
Figure 1. Assembly of BLDC Hub motor The approach of VARCAS has set off the work of a Six-phase BLDC Hub motor. The existing 3—phase BLDC Hub motor specifications are given in table 1. This BLDC Hub motor is dismantled, and its stator is rewound with the six — phase winding layout, which is determined by author’s presented direct approach. The complete assembly of the Hub motor is shown in figure 1.
Table 2. Each Coil offset angle and it’s associated In & Out slots phase double layer concentrated winding layout designed for the existing 48 slots, 52 poles Hub motor using the proposed direct approach method. This Six — phase winding layout developed is depicted in figure 2. A 15 strands copper conductor used in the winding and each strand gauge is 25S WG. There are 6 turns in each coil of phase. The winding was designed in such a way to keep the stator slot fill factor in practical limits [22]. Selecting coils numbered 5, 6, 7, 8, 29, 30, 31, and 32 from table 4 to form the phase D winding coils and its layout as shown in table 6. Keeping phase offset of 60° E (4 slots) w.r.t the phase D coils, phase B coils can be placed in the slots. Selecting coils numbered 9, 10, 11, 12, 33, 34, 35, and 36 gives the phase B winding coils. Similarly, phases E, C and F coils are placed in the slots keeping phase offset of 60° E with respect to each phase and choosing the coils close to 0° E. Table 7 shows Six —
Table 2. Each Coil offset angle and it’s associated In & Out slots phase double layer concentrated winding layout designed for the existing 48 slots, 52 poles Hub motor using the proposed direct approach method. This Six — phase winding layout developed is depicted in figure 2. A 15 strands copper conductor used in the winding and each strand gauge is 25S WG. There are 6 turns in each coil of phase. The winding was designed in such a way to keep the stator slot fill factor in practical limits [22]. Selecting coils numbered 5, 6, 7, 8, 29, 30, 31, and 32 from table 4 to form the phase D winding coils and its layout as shown in table 6. Keeping phase offset of 60° E (4 slots) w.r.t the phase D coils, phase B coils can be placed in the slots. Selecting coils numbered 9, 10, 11, 12, 33, 34, 35, and 36 gives the phase B winding coils. Similarly, phases E, C and F coils are placed in the slots keeping phase offset of 60° E with respect to each phase and choosing the coils close to 0° E. Table 7 shows Six —
Table 3. The principal angle of each coil with respect to the first coil and it’s associated In & Out slots
Table 3. The principal angle of each coil with respect to the first coil and it’s associated In & Out slots
Table 5. Phase A coils with In & Out slots
Table 5. Phase A coils with In & Out slots
Table 4. Changed winding direction of coils whose principal angle > 90° E and it’s associated In & Out slots Research Article | Volume 12, Issue 3 | Pages 981-990 | e-ISSN: 2347-470X PEECUTPIGQUiViicsi JUVUULTICI Ui Electrical and Electronics Research (IJEER)
Table 4. Changed winding direction of coils whose principal angle > 90° E and it’s associated In & Out slots Research Article | Volume 12, Issue 3 | Pages 981-990 | e-ISSN: 2347-470X PEECUTPIGQUiViicsi JUVUULTICI Ui Electrical and Electronics Research (IJEER)
Table 6. Phase D coils with In & Out slots
Table 6. Phase D coils with In & Out slots
of hall sensors begins with calculating the mechanical angle of each slot.
of hall sensors begins with calculating the mechanical angle of each slot.
2.2. Placing of Hall sensors The number of hall sensors used for BLDC hub motor is equal to the number of phases. Typically, more Hall sensors might be required to provide the necessary position feedback to handle the six phases effectively. This requires strategic placement to cover multiple phases and ensure reliable operation. Implications for the placement and utilization of Hall sensors, such as each sensor must be positioned to capture accurate rotor position data corresponding to the increased number of phases. The placement of Hall sensors must be carefully aligned to accurately detect the rotor position and facilitate the correct sequencing of the phase currents. Precise alignment of the Hall sensors becomes even more crucial with additional phases. The six hall sensors are to be placed 60° E apart from each other. There are two ways to place the hall sensor, one is by mounting it on a board inside the motor positioned to pick up the magnetic flux and the other is by mounting it in the stator slots. In this research work, it is proposed to place it in the stator slot. Placing Research Article | Volume 12, Issue 3 | Pages 981-990 | e-ISSN: 2347-470X
2.2. Placing of Hall sensors The number of hall sensors used for BLDC hub motor is equal to the number of phases. Typically, more Hall sensors might be required to provide the necessary position feedback to handle the six phases effectively. This requires strategic placement to cover multiple phases and ensure reliable operation. Implications for the placement and utilization of Hall sensors, such as each sensor must be positioned to capture accurate rotor position data corresponding to the increased number of phases. The placement of Hall sensors must be carefully aligned to accurately detect the rotor position and facilitate the correct sequencing of the phase currents. Precise alignment of the Hall sensors becomes even more crucial with additional phases. The six hall sensors are to be placed 60° E apart from each other. There are two ways to place the hall sensor, one is by mounting it on a board inside the motor positioned to pick up the magnetic flux and the other is by mounting it in the stator slots. In this research work, it is proposed to place it in the stator slot. Placing Research Article | Volume 12, Issue 3 | Pages 981-990 | e-ISSN: 2347-470X
Figure 3. Hall sensors placement (a) 6 hall sensors grouped into two sets with PCBs; (b) Final placement with packaging.
Figure 3. Hall sensors placement (a) 6 hall sensors grouped into two sets with PCBs; (b) Final placement with packaging.
Figure 4. (a) Block diagram of 6-phase BLDC Hub motor; (b) Circuit diagram of the 6-phase windings excited with two inverter sets. Research Article | Volume 12, Issue 3 | Pages 981-990 | e-ISSN: 2347-470X The block diagram of the closed loop control system of developed Six-phase BLDC Hub motor and circuit diagram of stator winding excitation with two inverter sets is shown in figure 4. Launchpad F28069M Piccolo™, a specific model of a development board of Texas Instruments™ is used to generate the PWM pulses to two Inverter sets with the help of feedback signals of hall sensors. This control board is equipped with a TMS320F28069M 32-bit MCU featuring 90 MHz C28x CPU, 256 KB Flash, 12-bit ADC, 2 encoder interfaces (eQEP) and 16 PWM pins. HEIL TIGUVilal JUULTICN Ui Electrical and Electronics Research (IJEER)
Figure 4. (a) Block diagram of 6-phase BLDC Hub motor; (b) Circuit diagram of the 6-phase windings excited with two inverter sets. Research Article | Volume 12, Issue 3 | Pages 981-990 | e-ISSN: 2347-470X The block diagram of the closed loop control system of developed Six-phase BLDC Hub motor and circuit diagram of stator winding excitation with two inverter sets is shown in figure 4. Launchpad F28069M Piccolo™, a specific model of a development board of Texas Instruments™ is used to generate the PWM pulses to two Inverter sets with the help of feedback signals of hall sensors. This control board is equipped with a TMS320F28069M 32-bit MCU featuring 90 MHz C28x CPU, 256 KB Flash, 12-bit ADC, 2 encoder interfaces (eQEP) and 16 PWM pins. HEIL TIGUVilal JUULTICN Ui Electrical and Electronics Research (IJEER)
Table 8. Three — phase Inverter Set1 and Set2 switching logic 2.4. Development of hardware system The switching control logic to generate PWM pulses to the two sets of 3 — phase Inverters is shown in table 8. The developed logic implemented by programming a TI C2000™ based MCU platform through the MATLAB Simulink. The Six — phase winding of BLDC Hub motor is grouped into two sets of Three — phase and the six Hall sensors grouped into
Table 8. Three — phase Inverter Set1 and Set2 switching logic 2.4. Development of hardware system The switching control logic to generate PWM pulses to the two sets of 3 — phase Inverters is shown in table 8. The developed logic implemented by programming a TI C2000™ based MCU platform through the MATLAB Simulink. The Six — phase winding of BLDC Hub motor is grouped into two sets of Three — phase and the six Hall sensors grouped into
two sets, since two 3-phase inverter sets are used to supply the stator of the six-phase BLDC Hub motor. The phase offset between the two inverters on each leg is maintained at 60° E through the gate switching pulses of corresponding legs. The hardware setup of inverters, a gate driver board, F28069 Controller, and six-phase hub motor are shown in figure 5. Increasing the number of winding phases from three to six in BLDC Hub motor has certain implications for the inverter system used to drive the motor. Such as the commutation control becomes complex as each phase needs precise timing for switching. The control algorithm for the inverter becomes sophisticated, inverter requires more electronic components than its three-phase counterpart, including additional power switches, gate drivers, and potentially more complex digital signal processing capabilities. This increase in components can lead to a rise in the overall cost and size of the inverter system. But the shift to a six-phase offers notable benefits in terms of performance, reliability, and efficiency. These advantages can make the transition appealing for applications demanding high- performance and robust electric motor solutions.
two sets, since two 3-phase inverter sets are used to supply the stator of the six-phase BLDC Hub motor. The phase offset between the two inverters on each leg is maintained at 60° E through the gate switching pulses of corresponding legs. The hardware setup of inverters, a gate driver board, F28069 Controller, and six-phase hub motor are shown in figure 5. Increasing the number of winding phases from three to six in BLDC Hub motor has certain implications for the inverter system used to drive the motor. Such as the commutation control becomes complex as each phase needs precise timing for switching. The control algorithm for the inverter becomes sophisticated, inverter requires more electronic components than its three-phase counterpart, including additional power switches, gate drivers, and potentially more complex digital signal processing capabilities. This increase in components can lead to a rise in the overall cost and size of the inverter system. But the shift to a six-phase offers notable benefits in terms of performance, reliability, and efficiency. These advantages can make the transition appealing for applications demanding high- performance and robust electric motor solutions.
Experimental wave forms of hall sensor feedback, switching gate pulses, line voltages and current are shown through figure 6 to figure 7. The experimental loading values of 3—phase and six—phase BLDC Hub motors are listed in table 9.
Experimental wave forms of hall sensor feedback, switching gate pulses, line voltages and current are shown through figure 6 to figure 7. The experimental loading values of 3—phase and six—phase BLDC Hub motors are listed in table 9.
Figure 6. (a) Hall Sensor Ha & Hb feedback signals of set1 having 120° phase offset; (b) Gate Pulses of T11 & T13 with 120° phase offset An existing 3—phase BLDC Hub motor converted to a six—phase BLDC Hub motor. Six-phase and 3—phase BLDC Hub motors are loaded at common load conditions, for performance comparison.
Figure 6. (a) Hall Sensor Ha & Hb feedback signals of set1 having 120° phase offset; (b) Gate Pulses of T11 & T13 with 120° phase offset An existing 3—phase BLDC Hub motor converted to a six—phase BLDC Hub motor. Six-phase and 3—phase BLDC Hub motors are loaded at common load conditions, for performance comparison.
: 4, CONCLUSIONS dynamic radial forces on the rotor resulting in less vibration and noise. Hence the presented direct approach is a good choice for determining the winding layout for conversion. It is also valid for other poly — phase winding layouts of more than three — phases. Six-phase and 3—phase BLDC Hub motors are loaded at common load conditions, for performance comparison, and experimental results of both the motors presented. The results show that, at the rated output power of about 850W, the 3 — Phase Hub motor produced 15.56 N-m torque whereas the 6 — Phase Hub motor produced 18.87 N-m. Thus, an increase of 21.7% of torque is obtained in the proposed Six — phase BLDC Hub motor than the three phase BLDC motor Hub of same The Six — Phase concentrated the double layer winding layout was developed for existing 48 slots, 52 magnets BLDC Hub motor using the proposed direct approach method. The winding layout has a winding factor of 0.98 and the no-load cogging torque pulsations over one revolution of the rotor is 624. Cros’ method does not indicate phase offset and angular spread of coils around the slots of the stator periphery is unsymmetric even though the number of coils in a phase is an even number. Whereas in the proposed method phase offset is clearly indicated and it is symmetric with minimum angular spread. The proposed six-phase winding layout produces balanced
: 4, CONCLUSIONS dynamic radial forces on the rotor resulting in less vibration and noise. Hence the presented direct approach is a good choice for determining the winding layout for conversion. It is also valid for other poly — phase winding layouts of more than three — phases. Six-phase and 3—phase BLDC Hub motors are loaded at common load conditions, for performance comparison, and experimental results of both the motors presented. The results show that, at the rated output power of about 850W, the 3 — Phase Hub motor produced 15.56 N-m torque whereas the 6 — Phase Hub motor produced 18.87 N-m. Thus, an increase of 21.7% of torque is obtained in the proposed Six — phase BLDC Hub motor than the three phase BLDC motor Hub of same The Six — Phase concentrated the double layer winding layout was developed for existing 48 slots, 52 magnets BLDC Hub motor using the proposed direct approach method. The winding layout has a winding factor of 0.98 and the no-load cogging torque pulsations over one revolution of the rotor is 624. Cros’ method does not indicate phase offset and angular spread of coils around the slots of the stator periphery is unsymmetric even though the number of coils in a phase is an even number. Whereas in the proposed method phase offset is clearly indicated and it is symmetric with minimum angular spread. The proposed six-phase winding layout produces balanced
Figure 7. (a) Line Voltage VAB & VDE of Six-phase Hub motor with 600 phase difference; (b) Line voltage VAB & Current IA waveforms of Set 1 winding of Six-phase Hub motor
Figure 7. (a) Line Voltage VAB & VDE of Six-phase Hub motor with 600 phase difference; (b) Line voltage VAB & Current IA waveforms of Set 1 winding of Six-phase Hub motor
Figure 9. Plot between Efficiency and Torque Figure 8. (a) Plot between Input power and Torque; (b) Plot between Output power and Torque Table 9. Three — phase & Six — Phase BLDC Hub motor experimental loading summary data
Figure 9. Plot between Efficiency and Torque Figure 8. (a) Plot between Input power and Torque; (b) Plot between Output power and Torque Table 9. Three — phase & Six — Phase BLDC Hub motor experimental loading summary data
Research Article | Volume 12, Issue 3 | Pages 981-990 | e-ISSN: 2347-470X PEETUUTTIGUIVIIGs JUVUULLTICI Ui Electrical and Electronics Research (IJEER)
Research Article | Volume 12, Issue 3 | Pages 981-990 | e-ISSN: 2347-470X PEETUUTTIGUIVIIGs JUVUULLTICI Ui Electrical and Electronics Research (IJEER)
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BLDC MotorHub Motor
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