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EP-4736312-A1 - THREE-LEVEL GENERIC MOTOR DRIVER

EP4736312A1EP 4736312 A1EP4736312 A1EP 4736312A1EP-4736312-A1

Abstract

A driver for a brushless DC electric motor supplies direct voltage to each of two terminals of the individual stator coils to drive the motor. The driver comprises an input supply voltage which feeds the motor via three power terminals, a +vdc terminal, a middle point terminal, and a — vclc terminal. Each stator coil terminal of the motor is connected via switches to the power terminals and some of the terminals may be connected to those of other coils. The switches allow a state in which a respective terminal is left open. The driver includes a controller to operate the switches in accordance with a switching protocol to control the electric motor.

Inventors

  • AHARON, ILAN

Assignees

  • Ariel Scientific Innovations Ltd.

Dates

Publication Date
20260506
Application Date
20240628

Claims (20)

  1. 1. An electric motor and driver, the electric motor having at least three coils, the driver having three driver terminals to supply three levels of direct voltage to said coils selectively to drive said motor; the motor coils each having first and second coil terminals respectively, respective first coil terminals being selectively connectable to all three of said driver terminals and respective second coil terminals being selectively connectible to two of said driver terminals or to others of said respective second coil terminals.
  2. 2. The electric motor and driver of claim 1, wherein said three driver terminals comprise a +v clc terminal, a middle point terminal, and a — v clc terminal.
  3. 3. The electric motor and driver of claim 1 or claim 2, wherein each coil terminal of said motor is connected via switches to respective ones of said driver terminals.
  4. 4. The electric motor and driver of claim 3, comprising a controller to operate said switches in accordance with a switching protocol to drive said electric motor.
  5. 5. The electric motor and driver of claim 4, wherein said switching protocol comprises combinations wherein ones of said motor coils are connected to others of said motor coils.
  6. 6. The electric motor and driver of claim 4 or claim 5, wherein said switching protocol includes combinations in which ones of said coil terminals are left open.
  7. 7. The electric motor and driver of any one of claims 3 to 6, wherein said three driver terminals comprise a +v clc terminal and wherein one of said switches is located to connect said +vdc driver terminal to a common node of said respective second coil terminals.
  8. 8. The electric motor and driver of any one of claims 3 to 7, wherein said switches are controllable to provide current paths between any combination of said plurality of motor coils.
  9. 9. The electric motor and driver of any one of claims 3 to 8, wherein said switches are controllable to provide 120 degree commutation. SUBSTITUTE SHEET (RULE 26)
  10. 10. The electric motor and driver of any one of claims 3 to 9, wherein said switches are controllable to provide 180 degree commutation.
  11. 11. The electric motor and driver of any one of claims 3 to 10, wherein said switches are controllable to provide pulse width modulation.
  12. 12. The electric motor and driver of any one of claims 3 to 11, wherein said switches are controllable to provide a space vector-based switching algorithm.
  13. 13. The electric motor and driver of any one of the preceding claims, comprising three motor coils, and five switches per motor coil.
  14. 14. The electric motor and driver of any one of the preceding claims, comprising three motor coils, five switches per motor coil and one additional switch.
  15. 15. The electric motor and driver of any one of the preceding claims, comprising more than three motor coils, and five switches per motor coil.
  16. 16. The electric motor and driver of any one of the preceding claims, comprising more than three motor coils, five switches per motor coil and one additional switch.
  17. 17. A power source for the driver of any one of the preceding claims, the power source comprising a power train for an electric vehicle.
  18. 18. An electric motor having at least three coils, each coil extending between first and second terminals respectively, and wherein each of said first and second terminals are available to an external control system.
  19. 19. A control system to drive the motor of claim 14, comprising a DC power source having a positive power line, a negative power line and a neutral power line, and switches for selective connection, wherein one switch respectively connects each first terminal to said positive power line, one switch respectively connects each first terminal to said negative power line, one switch respectively connects each said first terminal to said neutral power line, one switch connects a common node of each said second terminal to said positive power line, one switch respectively SUBSTITUTE SHEET (RULE 26) 23 July 2024 16 connects each said second terminal to said common node, and one switch respectively connects each said second terminal to said negative power line.
  20. 20. A method of driving an electric motor, the electric motor having at least three coils, each coil extending between first and second terminals respectively, and wherein each of said first and second terminals are available to an external control system, the method comprising: selectively connecting each of said first terminals to a positive power line of a DC power source, to a negative power line of said DC power source and to a neutral power line; selectively connecting each of said second terminals to a common node or to said negative power line; and selectively connecting said common node to said positive power line, and wherein said selectively connecting of said first terminals, said second terminals and said common node is in accordance with a predetermined drive sequence. SUBSTITUTE SHEET (RULE 26)

Description

THREE-LEVEL GENERIC MOTOR DRIVER RELATED APPLICATION/S This application claims the benefit of priority of U.S. Provisional Patent Application No. 63/523,662, filed on June 28, 2023, the contents of which are incorporated herein by reference in their entirety. FIELD AND BACKGROUND OF THE INVENTION The present invention, in some embodiments thereof, relates to a driver for an electric motor and, more particularly, but not exclusively, to a three-level generic motor driver. Electronic drivers are important tools since they are used in electric motors in the domestic and work environments as well as transportation, and various industrial processes. The evolution of electric vehicles catalyzed the massive growth of electric motor drivers. Many types of electric motors are employed in electric vehicles, and such motors include inductance machines, permanent magnet synchronous machines, switched reluctance motors, and permanent brushless de motors. In most cases, the supply voltage source is direct current (de), while the three-phase motor requires an alternating current (ac) source; thus, a driver is necessary. There are four basic types of power electronics converters. A rectifier (ac-dc), ac-ac, dc- dc, and inverter (dc-ac). The relevant converters for driving three-phase motors are the ac-ac when there is an ac Grid source or ac micro-grid, and inverters when there is a de source such as a battery. In ac-ac converters, the output terminal has an amplitude which is different from the input amplitude and may also be at a different frequency. When the driver varies the output frequency, the ac-ac converter contains a rectifier, de bus, and inverter. Besides the synchronous machine, all the other electric motor types require a variable frequency source. As mentioned earlier, the motors are characterized by three-phase coils governed mainly by a voltage or current source inverter that allows for control of the amplitude and frequency. Different loads are characterized by their torque and speed, where the load power deviates or remains constant. In the transportation category, during the start of driving, the vehicle accelerates, the torque is stable, and the speed rises linearly. Then, in cruising, the torque falls as the angular velocity increases, resulting in constant power operation. During the breaking period, the speed decreases, and the torque is negative. Reference is now made to Fig. 1, which is a simplified illustration of a closed-loop control system required to conserve the operating point at a determined value in a three-level T-type universal inverter. In most cases, the reference signal for the controller is the speed or the torque. Energy source 10 provides power to driver 12 which in turn provides pulse width modulated (pwm) signals to motor 14. The motor in turn drives load 16. However, the motor and the driving circuit elements must operate within allowed limits; therefore, a current limit control loop is commonly added in cascade to the control system. Controller 18 thus receives feedback from the motor, such as voltage, current, speed and torque. Input from throttle 20 sets a control point, and the control system’s main tasks are to improve efficiency, enable stable speed/torque/power control for transient and steady- state for operations in all four quadrants, and enhance optimal control strategies. Several control methods apply to motor speed control. Techniques include scalar control, field-oriented control, direct torque control, space vector-based algorithms, fuzzy logic control, voltage-level-based algorithms, and neural network control. These control methods can be employed for many types of dc-ac converters. The three-phase voltage source inverter (VSI) is the most common driver, whereas a two-level de voltage source may provide a feed. In motor applications, the VSI coils utilize the motor inductors; thus, the driving circuit is minimized and requires only six switches, as presented in Figure 2, which shows a full bridge voltage source inverter. Specifically, Fig. 2 shows an energy source 22, which is connected via six switches Q1..Q6 to three motor windings, a-a’, b-b’ and c-c’. The paired switches, Q1-Q4, Q2- Q5 and Q3- Q6 cannot be set at the same time or that would cause a short circuit, and each winding input may be selectively connected to the positive or the negative power line. The winding outputs are all connected together at neutral node 24 and are not available to the control system. The full bridge voltage source inverter is also named the six -block commutation, and significant downsides include a relatively high torque ripple and unwanted d-axis currents. Specific topologies include the multilevel VSI, the neutral point clamped, the flying capacitor, the cascaded h-bridge, and others, and their use may reduce the current ripple and total harmonic distortion (THD). The drawback is that switching count rises, and the control circuitry is more complex. The main modulation