Boosted converter for pulsed electric machine control

Patent metadata

Field	Value
Publication number	US-10944352-B2
Application number	US-202016818570-A
Country	US
Kind code	B2
Filing date	Mar 13, 2020
Priority date	Mar 19, 2018
Publication date	Mar 9, 2021
Grant date	Mar 9, 2021

Abstract

A boost circuit is arranged to reduce rise and fall times of pulsed power used for pulsed control operation of electric machines. Magnetic energy present in the electric machine at the end of a pulse is extracted by the boost circuit to reduce the pulse fall time. The energy is stored by the boost circuit and then applied at the beginning of a subsequent pulse to reduce the rise time. By reducing rise and fall times compared to not using such a boost circuit, machine efficiency is improved.

First claim

What is claimed is:

1. An apparatus, comprising:
a power supply;
an electric machine having windings with magnetic energy stored in the windings;
an electric machine controller configured to selectively operate the electric machine in a pulsed mode; and
a power converter coupled between the power supply and the electric machine, the power converter arranged to deliver pulsed power to or receive pulsed power from the windings of the electric machine in response to the machine controller;
wherein the power converter includes a boost circuit arranged to extract at least some of the magnetic energy present in the electric machine at the end of a pulse to reduce the pulse fall time, store at least some of the energy, and apply at least some of the energy at the beginning of a subsequent pulse, thereby reducing rise and fall times of the pulsed power relative to the rise and fall times of the pulsed power without the boost circuit.

2. An apparatus as recited in claim 1 , wherein during a pulse of pulsed operation the electric machine operates at substantially its maximum efficiency operating point.

3. An apparatus as recited in claim 1 , wherein the power supply is a DC power supply.

4. An apparatus as recited in claim 3 , wherein the power converter is operated as a power inverter that converts a DC power produced by the DC power supply to an AC power to drive the electric machine.

5. An apparatus as recited in claim 3 , wherein the power converter is operated as a power rectifier that converts an AC power produced by the electric machine to a DC power that is stored in the DC power supply.

6. An apparatus as recited in claim 3 , wherein the boost circuit includes a switch electrically connected between a terminal of the DC power supply and a switching network that controls power to and from the electric machine.

7. An apparatus as recited in claim 6 , wherein the boost circuit includes a capacitor electrically selectively connected with the switching network by the switch.

8. An apparatus as recited in claim 3 , wherein the boost circuit includes a diode between the power supply and a switching network that controls power to and from the electric machine.

9. An apparatus as recited in claim 1 , wherein the boost circuit uses magnetic energy stored in the stator windings to temporarily boost the available electric potential to drive the electric machine.

10. An apparatus as recited in claim 1 , wherein the boost circuit boosts the available electric potential to drive the electric machine in a series of one or more boost steps during an off period of the electric machine.

11. The apparatus of claim 1 , wherein the power converter is further arranged to vary the delivered pulsed power to the electric machine in order to vary a duty cycle of a pulsed torque output generated by the electric machine to meet a requested torque demand.

12. The apparatus of claim 1 , wherein the boost circuit reduces rise or fall times of the pulsed power relative to the rise or fall times of the pulsed power without the boost circuit by at least a factor of two.

13. The apparatus of claim 1 , where in the electric machine has a switching frequency ranging from 10 Hz to 50 kHz.

14. A method of operating an electric machine, comprising:
operating the electric machine in a pulsed manner, such that a power applied to or taken from the electric machine consists of a series of pulses separated by periods of reduced power, wherein a duty cycle of the series of pulses is determined so as to deliver a desired torque magnitude;
extracting at least some of a magnetic energy present in the electric machine at the end of a pulse to reduce the pulse fall time;
storing at least some of the energy; and
applying at least some of the energy at the beginning of a subsequent pulse thereby reducing rise and fall times of the pulsed power.

15. A method as recited in claim 14 , wherein the power applied to or taken from the electric machine during a pulse in the series of pulses operates the electric machine at substantially a most efficient operating point for the electric machine.

16. A method as recited in claim 14 , wherein the series of pulses is produced by a power converter that includes a boost circuit and the boost circuit is arranged to reduce rise and fall times of pulses in the series of pulses relative to the rise and fall times of the pulses without the boost circuit.

17. A method as recited in claim 16 , wherein the power converter is operated as a power inverter that converts a DC power produced by a DC power supply to AC power to drive the electric machine.

18. A method as recited in claim 16 , wherein the power converter is operated as a power rectifier that converts AC power produced by the electric machine to DC power that is stored in the DC power supply.

19. A method as recited in claim 14 , wherein the electric machine is operated as an electric motor or an electric generator.

20. A method as recited in claim 14 , wherein the electric machine is operated as an electric motor and the series of pulses is produced by a power converter that includes a boost circuit, the boost circuit increases an available electric potential to drive the electric motor at the beginning of the at least one pulse in the series of pulses.

21. A method as recited in claim 20 , wherein the boost circuit increases the available electric potential to drive the electric motor at the end of a pulse preceding the at least one pulse in the series of pulses.

22. A method as recited in claim 20 , wherein the boost circuit increases the available electric potential to drive the electric motor during an off period preceding the at least one pulse in the series of pulses.

23. A method as recited in claim 22 , wherein the boost circuit increases the available electric potential to drive the electric motor in a series of one or more steps.

24. A method of operating an electric machine, comprising:
operating the electric machine in a pulsed manner, such that a power applied to or taken from the electric machine consists of a series of pulses separated by periods of reduced power, wherein a duty cycle of the series of pulses is determined so as to deliver a desired torque magnitude; and
increasing the electrical potential difference between a positive voltage bus and a negative voltage bus so as to reduce transition times of the series of pulses respectively.

25. A method as recited in claim 24 wherein the electric potential to drive the electric motor is increased in a series of one or more steps during the periods between the series of pulses.

26. A method as recited in claim 24 wherein the electrical potential difference exceeds the electrical potential difference of a power supply used to store or delivery energy to the electrical machine.

27. A method as recited in claim 24 wherein the power applied to or taken from the electric machine during the periods of negligible power is selected from a group consisting of less than 10%, 5%, 1%, 0.5%, and 0.1% of the power supplied to or taken from the electric machine during the series of pulses.

28. A system, comprising:
an electric motor;
a torque modulation module arranged to:
(a) receive a torque demand;
(b) ascertain if the received torque demand is less than a peak efficiency torque of the motor; and
(c) generate a modulated waveform if the torque demand is less

Assignees

• Tula Technology Inc

Inventors

• Mazda Babak
• Tripathi Adya S
• Carvell Paul

Classifications

• H02P27/085 Primary

  wherein the PWM mode is adapted on the running conditions of the motor, e.g. the switching frequency · CPC title

• Y02T10/70

  Energy storage systems for electromobility, e.g. batteries · CPC title

• H02P2201/09

  Boost converter, i.e. DC-DC step up converter increasing the voltage between the supply and the inverter driving the motor · CPC title

• B60L15/007

  Physical arrangements or structures of drive train converters specially adapted for the propulsion motors of electric vehicles · CPC title

• H02P21/02

  specially adapted for optimising the efficiency at low load · CPC title