Reliable current sensing for inverter-controlled electronic machine

• US 9,455,653 B1
• Filed: 03/05/2015
• Issued: 09/27/2016
• Est. Priority Date: 03/05/2015
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Garcha, Jaswant S.
• Primary Examiner(s): DUDA, RINA I
• Application Number:
  US14/639,153
• Publication Number:
  US 20160261213A1
• Time in Patent Office: 572 Days
• Field of Search: 318/727, 318/800, 318/801, 318/400.38
• US Class Current: 1/1
• CPC Class Codes: B60L 50/51 characterised by AC-motors
• CPC Class Codes: G01R 15/202 using Hall-effect devices Hall elements in arrangements for measuring electrical power G01R21/08
• CPC Class Codes: G01R 31/343 in operation
• CPC Class Codes: G01R 31/42 AC power supplies
• CPC Class Codes: H02K 11/27 Devices for sensing current, or actuated thereby overcurrent protection responsive to temperature of the machines or parts thereof, e.g. windings, H02K11/25
• CPC Class Codes: H02K 11/33 Drive circuits, e.g. power electronics H02K11/38 takes precedence
• CPC Class Codes: H02P 27/06 using dc to ac converters or inverters H02P27/05 takes precedence
• CPC Class Codes: H02P 27/08 with pulse width modulation
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

Phase currents of an inverter-driven electric machine are measured by mounting phase conductors of each respective phase current into a central passage of a respective flux core. A plurality of current sensors are mounted into a gap of each respective flux core to generate a respective plurality of current signals for each phase current. The Hall-effect devices are connected to a plurality of multi-channel op amp devices for conditioning the current signals such that each set of Hall-effect devices is connected to a different one of the op amp devices and such that each op amp device receives one current signal corresponding to each phase current. Thus, a valid conditioned current signal corresponding to each phase conductor is generated by the op amp devices unless there are multiple simultaneous failures of the Hall-effect devices and the op amp devices.

Claims

1. An electric drive for an electric vehicle with a multi-phase electric machine, comprising:

an inverter bridge having inverter switches arranged in a plurality of phase legs;

an inverter controller for controllably switching the inverter switches;

first and second phase conductors coupled between respective inverter phase legs and respective phase windings of the electric machine;

first and second flux cores each having a central passage and a gap, respectively, wherein the first and second phase conductors pass through the central passages of the first and second flux cores, respectively;

a first plurality of current sensors comprised of a predetermined number of first Hall-effect devices, each of the first Hall-effect devices disposed in the gap of the first flux core to generate respective first current signals;

a second plurality of current sensors comprised of the predetermined number of second Hall-effect devices, each of the second Hall-effect devices disposed in the gap of the second flux core to generate respective second current signals; and

a plurality of multi-channel op amp devices for conditioning the current signals and coupling them to an inverter controller, wherein the number of multi-channel op amp devices equals the predetermined number;

wherein each one of the first Hall-effect devices is connected to a different one of the op amp devices, and wherein each one of the second Hall-effect devices is connected to a different one of the op amp devices, whereby a valid conditioned current signal corresponding to each phase conductor is received by the inverter controller unless there are multiple failures of the Hall-effect devices and the op amp devices.

2. The electric drive of claim 1 wherein the electric machine has three phases, and wherein the electric drive further comprises:

a third phase conductor coupled between a respective inverter phase leg and a respective phase winding of the electric machine;

a third flux core having a central passage and a gap, wherein the third phase conductor passes through the central passage of the third flux core; and

a third plurality of current sensors comprised of three Hall-effect devices, each of the third Hall-effect devices disposed in the gap of the third flux core to generate respective third current signals;

wherein the predetermined number is three, and wherein each one of the third Hall-effect devices is connected to a different one of the three op amp devices.

3. The electric drive of claim 1 wherein the inverter controller includes the predetermined number of analog-to-digital converters, and wherein each op amp device is connected to a different one of the analog-to-digital converters.

4. The electric drive of claim 1 wherein the inverter controller compares the conditioned current signals corresponding to each phase conductor in order to detect a faulty conditioned current signal.

5. The electric drive of claim 1 wherein each plurality of Hall-effect devices are mounted on a circuit board in a respective row, and wherein a respective flux core and the circuit board are installed in a housing so that the respective gap receives the respective row of Hall-effect devices.

6. A method of measuring phase currents of an inverter-driven electric machine, comprising:

mounting phase conductors of each respective phase current into a central passage of a respective flux core;

mounting a respective plurality of current sensors into a gap of each respective flux core to generate a respective plurality of current signals for each phase current, wherein each plurality of current sensors is comprised of a predetermined number of Hall-effect devices; and

connecting the Hall-effect devices to a plurality of multi-channel op amp devices for conditioning the current signals such that each one of a respective plurality of Hall-effect devices is connected to a different one of the op amp devices and such that each op amp device receives one current signal corresponding to each phase current;

whereby a valid conditioned current signal corresponding to each phase conductor is generated by the op amp devices unless there are multiple simultaneous failures of the Hall-effect devices and the op amp devices.

7. The method of claim 6 wherein an inverter controller controls an inverter bridge to supply the phase currents to the electric machine, the method further comprising:

converting to digital representation the conditioned current signals using a plurality of analog-to-digital converters, wherein each op amp device is connected to a different one of the analog-to-digital converters.

8. The method of claim 7 further comprising:

the inverter controller comparing the conditioned current signals corresponding to each phase conductor in order to detect a faulty conditioned current signal.