Hysteresis-controlled DC-DC boost converter for aerial vehicles

Patent metadata

Field	Value
Publication number	US-10536078-B2
Application number	US-201715717087-A
Country	US
Kind code	B2
Filing date	Sep 27, 2017
Priority date	May 4, 2017
Publication date	Jan 14, 2020
Grant date	Jan 14, 2020

Abstract

A power conversion unit may include two or more power modules for providing high-voltage direct current power to electrical loads, such as one or more propulsion motors aboard an aerial vehicle. Each of the power modules may be controlled by hysteresis, and may include one or more pairs of transistors that are switched by a gate driver with respect to differences between a reference current and a sensed current passing through a boost inductor. The number, size and shape of the power modules may be selected to accommodate the electrical loads, and may be switched on or off, as necessary. The power conversion unit may feature at least one more power module than is required to meet all anticipated electrical loads, thereby ensuring that the power conversion unit may continue to provide power even in the event that one of the power modules experiences a fault of any kind.

First claim

What is claimed is:

1. An aerial vehicle comprising:
a frame;
a direct current battery mounted to the frame;
a plurality of propulsion motors mounted to the frame, wherein each of the propulsion motors is configured to rotate a propeller about an axis defined by a shaft;
a power conversion unit configured to receive electrical power from the battery and to provide electrical power to each of the propulsion motors, wherein the power conversion unit comprises:
a housing mounted to the frame;
a plurality of power modules releasably mounted within the housing, wherein each of the power modules is configured to provide electrical power at up to a predetermined voltage level and a predetermined current level, and wherein each of the power modules comprises:
a boost inductor;
a current sensor aligned to sense a current flowing through the boost inductor and to generate a voltage signal corresponding to the current flowing through the boost inductor;
a pair of MOSFETs, wherein the pair of MOSFETs comprises a first MOSFET aligned in series between the boost inductor and at least one of the propulsion motors and a second MOSFET aligned in series between the boost inductor and ground;
a gate driver, wherein the gate driver is configured to supply a gate voltage to switch on or off each of the pair of MOSFETs;
an output capacitor in parallel with at least one of the propulsion motors;
an error amplifier, wherein a first input of the error amplifier is a reference voltage and a second input of the error amplifier is a voltage across the output capacitor, and wherein an output of the error amplifier is a voltage signal corresponding to a reference current; and
a hysteresis controller for controlling operations of the gate driver, wherein a first input of the hysteresis controller is the voltage signal corresponding to the reference current and a second input of the hysteresis controller is the voltage signal corresponding to the current flowing through the boost inductor sensed by the current sensor, and wherein an output of the hysteresis controller is a voltage signal to the gate driver for switching on one of the pair of MOSFETs and for switching off one of the pair of MOSFETs; and

a supervisory controller within the housing, wherein the supervisory controller is in communication with each of the power modules, and wherein the supervisory controller is configured to determine a predetermined number of the power modules required to provide electrical power in response to demand.

2. The aerial vehicle of claim 1 , wherein operating each of the propulsion motors requires electrical power from a first predetermined number of the power modules,
wherein the aerial vehicle comprises a second predetermined number of the power modules, and
wherein the second predetermined number is at least one greater than the first predetermined number.

3. The aerial vehicle of claim 1 , wherein each of the power modules further comprises a first isolation switch upstream of the boost inductor and a second isolation switch downstream of the first MOSFET, and
wherein each of the first isolation switch and the second isolation switch is in communication with the supervisory controller.

4. A power conversion unit comprising:
a housing;
a controller mounted within the housing;
a direct current power supply;
a first power module releasably mounted within the housing, wherein the first power module comprises:
a first boost inductor;
a first current sensor configured to sense a current passing through the first boost inductor;
a first pair of transistors;
a first gate driver configured to operate each of the first pair of transistors;
a first output capacitor;
a first error amplifier, wherein a first input to the first error amplifier is a first reference voltage associated with a first load on the first power module, wherein a second input to the first error amplifier is a first output voltage of the first power module, and wherein an output from the first error amplifier is a voltage signal representative of a first reference current determined based at least in part on a difference between the first reference voltage and the first output voltage of the first power module;
a first hysteresis controller, wherein a first input to the first hysteresis controller is the voltage signal representative of the first reference current, wherein a second input to the first hysteresis controller is a voltage signal representative of the current passing through the first boost inductor, and wherein an output from the first hysteresis controller is a first control signal for operating the first gate driver based at least in part on a difference between the first reference current and the current passing through the first boost inductor,
wherein a first one of the first pair of transistors is aligned in series between the first boost inductor and the load on the first power module, and wherein a second one of the first pair of transistors is aligned in series between the first boost inductor and ground;

a second power module releasably mounted within the housing, wherein the second power module comprises:
a second boost inductor;
a second current sensor configured to sense a current through the second boost inductor;
a second pair of transistors;
a second gate driver configured to operate each of the second pair of transistors;
a second output capacitor;
a second error amplifier, wherein a first input to the second error amplifier is a second reference voltage associated with a second load on the second power module, wherein a second input to the second error amplifier is a second output voltage of the second power module, and wherein an output from the second error amplifier is a second reference current determined based at least in part on a difference between the second reference voltage and the second output voltage of the second power module; and
a second hysteresis controller, wherein a first input to the second hysteresis controller is the voltage signal representative of the second reference current, wherein a second input to the second hysteresis controller is a voltage signal representative of the current passing through the second boost inductor, and wherein an output from the second hysteresis controller is a second control signal for operating the second gate driver based at least in part on a difference between the second reference current and the current passing through the second boost inductor;
wherein a first one of the second pair of transistors is aligned in series between the second boost inductor and the load on the second power module, and wherein a second one of the second pair of transistors is aligned in series between the second boost inductor and ground.

5. The power conversion unit of claim 4 , wherein the first control signal is configured to switch the first one of the first pair of transistors off and to switch the second one of the first pair of transistors on when the current flowing through the first boost inductor equals a zero voltage switching current, and
wherein the first control signal is configured to switch the first one of the first pair of transistors on and to switch the second one of the first pair of transistors off when the current flowing through the first boost inductor equals the first reference current.

6. The power conversion unit of claim 4 , wherein the first hysteresis controller is configured to select a switching frequency for the first one of the first pair of transistors and the second one of the first pair of transistors based at least in part on the difference between the first reference current and the current passing through the first boost inductor, and
wherein the first control signal is transmitted according to the switching frequenc

Assignees

• Amazon Tech Inc

Inventors

• Traube Joshua White

Classifications

• H02P7/29

  using pulse modulation · CPC title

• H02P7/291

  with on-off control between two set points, e.g. controlling by hysteresis · CPC title

• H02M3/1563

  without using an external clock (H02M3/158 takes precedence) · CPC title

• B64C27/14

  Direct drive between power plant and rotor hub · CPC title

• H02M3/1588

  comprising at least one synchronous rectifier element (H02M3/1582, H02M3/1584 take precedence) · CPC title