Resonant inverter control system

• US 6,570,780 B2
• Filed: 04/30/2002
• Issued: 05/27/2003
• Est. Priority Date: 05/17/2001
• Status: Expired due to Fees

• Current Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Original Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Inventors: Shinohara, Sadao, Furukawa, Katsuhiko
• Primary Examiner(s): NGUYEN, MATTHEW VAN
• Application Number:
  US10/134,535
• Publication Number:
  US 20020172062A1
• Time in Patent Office: 392 Days
• Field of Search: 363/16, 363/17, 363/95, 363/97, 363/98, 363/131, 363/132
• US Class Current: 363/98
• CPC Class Codes: B60L 15/025 using field orientation; Vector control; Direct Torque Control [DTC]
• CPC Class Codes: B60L 50/51 characterised by AC-motors
• CPC Class Codes: H02M 7/53873 with digital control
• CPC Class Codes: H02M 7/53875 with analogue control of three-phase output
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

An inverter control apparatus is provided which controls a resonant soft switching inverter circuit according to the operational principle that the number of the resonant inductors be reduced. When the three phase control signal of the control CPU 5 changes from the (1, 0, 0) state to (0, 0, 1), the drive signal generating device 6 causes a current to flow to the inductor Lr by making the auxiliary switching elements conductive, and when the current I4 flowing to the inductor Lr is the same as the maximum among the currents I1, I2, and I3 flowing through the load, turns OFF the IGBT Q1 and IGBT Q6. Next, the voltage sensors Vs2 and Vs5, which are connected to the IGBTs Q2 and Q5 of the main switching circuit, detect whether or not the voltage across the collector terminal and emitter terminal has become “zero”, and when the outputs Z2 and Z5 of the zero voltage detecting device 8 output the respective logical values “1”, the device signal generating device 6 outputs the switching control signals S2 and S5 that force the IGBTs Q2 and Q5 to conduct, and transit to a stationary condition.

Claims

1. A resonant inverter control apparatus that controls an inverter circuit comprising six main switching elements connected to form a three-phase bridge;

six free wheeling diodes and six snubber capacitors respectively connected in parallel between two terminals of the main switching elements that are made conductive or non-conductive by the switching control;

main switching circuits in which each of the connection points between three groups of main switching circuits that form each phase of a three phase bridge structure connected serially by pairs to each end of a power source serve as three phase output terminals for connecting the motor; and

an auxiliary switching circuit in which six auxiliary switching elements that force current to flow in one direction are connected to form a three phase bridge connection and resonant inductors is connected to the bridge circuit that respectively connects each connection point between said auxiliary elements to said three phase output terminals, comprising;

a three phase control device that outputs a three phase control signal that serves as a reference for controlling said main switching elements of said inverter circuit;

six voltage measuring devices that measure the voltage across two terminals of said main switching element;

zero voltage detecting device that detects that the voltage across any two terminal of said six main switching elements is zero by the output of said voltage measuring device;

four current measuring devices that respectively measures the three phase current flowing to said load and the induced current flowing to said inductors;

a resonant current arrival determining device that calculates the absolute value of the maximum value of said three phase current and whether or not the induced current is larger than this maximum value based on the output of said current measuring device; and

a drive signal generating device in which a switching control signal that forces conduction across said two terminals of said main switching element is output when the zero voltage detecting device detects that a voltage across said two terminals of the switching elements to be controlled is zero based on the control by said three phase control signal, and a switching control signal that interrupts the conduction across said two terminals of said main switching element that is the phase of the main switching element corresponding to this maximum value and has two terminals in a conducting state is output when said resonant current arrival determining device has determined that said induced current is larger than the absolute value of the maximum value of said three phase current.

2. A resonant inverter control apparatus according to claim 1 wherein:

said main switching elements are separated into first, second, and third upper level switching elements corresponding to each phase of the three phase bridge and fourth, fifth, and sixth lower level switching elements corresponding to each phase of the three phase bridge, and said auxiliary switching elements are separated into the seventh, eighth, and ninth switching elements that are respectively connected to said three phase output terminals that conduct only in the direction in which the current flows to each of the connecting points between said auxiliary switching elements, and the tenth, eleventh, and twelfth switching elements that are respectively connected to said three phase output terminals that conduct only in the direction in which the current flows out from each of the connection points between said auxiliary switching elements, said drive signal generating device outputs switching control signals that force said seventh, eighth, and ninth switching elements to conduct in synchronism with the three phase control signal that directs the output of a switching control signals that force said first, second, and third switching elements to conduct, and outputs switching control signals that force said tenth, eleventh, and twelfth switching elements to conduct in synchronism with said three phase signals that direct the output of switching signals that force said fourth, fifth, and sixth switching elements to conduct.

3. A resonant inverter control apparatus according to claim 1 or claim 2, wherein, for the signal of each phase of said three phase control signal, when the case in which the switching control signal forces conduction across the two terminals of the first, second, and third switching elements and the interrupts the conduction across the two terminals of the fourth, fifth, and sixth switching elements is represented by the logical value “

1” and

the case in which the switching control signals force conduction across the two terminals of the fourth, fifth, and sixth switching elements and interrupts the conduction across the two terminals of the first, second, and third switching elements is represented by the logical value “

0”

, the exclusive logical OR of the logical values representing said three phase signals of said three phase control signal output by the three phase control device is always the logical value “

1”

.

4. A resonant inverter control apparatus according to claim 3 wherein the state transitions of the three phase control signals output from said three phase control device satisfy either the case that the logical OR of the logical values that represent the signals for each of the phases of said three phase control signals after the state transition are identical to the logical OR of the logical values that represent the signals for each of the phases of said three phase signal after the state transition, or the case in which the logical values that represents the signals of each of the phases of said three phase control signals after state transition are inversions of the logical values representing the signals of each of the phases of said three phase signals after the state transition.

5. A resonant inverter control apparatus according to claim 1 or 2 wherein, when the output time during which said three phase control device continues to output said identical three phase signals is greater than the time during which said induced current flows through said inductors, and the maximum time of the conduction continuation time of said auxiliary switching element is equal to or less than the time during which said induced current flows through said inductors when any of said three phase currents is flowing at a maximum, the drive signal generating device outputs to said auxiliary switching element in a non-conducting state a switching control signal that forces said auxiliary switching element to conduct in synchronism with said three phase control signal that directs the output of a switching control signal to said main switching element, or outputs a switching control signal to said auxiliary switching elements in a conducting state a switching control signal that forces the interruption of conduction of said auxiliary switching elements when the maximum time of the conducting continuation time of said auxiliary switching element has been attained in the case that the output time of said three phase control signal is longer than the maximum time for the conduction continuation time of said auxiliary switching elements, or outputs a switching control signal that forces the interruption of the conduction of said auxiliary switching elements in synchronism with said three phase control signal that directs the output of the switching control signals to said main switching elements in the case that the output time of said three phase control signal is shorter than a maximum time for the conduction continuation time of said auxiliary switching elements.

6. A resonant inverter apparatus comprising an inverter circuit in which a direct current output by a power source is converted to a three phase alternating current and supplied to a three phase motor, a resonant circuit that is connected to the output terminal of the inverter circuit, and a control circuit that control the resonant circuit and the inverter circuit, wherein:

said inverter circuit comprises a three phase main circuit in which three circuits, one for each phase, connected in parallel, wherein a main switching element that is connected to the plus terminal of said power source and the main switching elements that are connected to the minus terminal of the power source are connected in series, and connected in parallel to diodes respectively connected to these two main switching elements;

capacitors that are connected in parallel to the main switching elements in each of the circuits for each phase;

load current sensors that detect a load current flowing across main connection points, at which two main switching elements in each of the circuits for each phase are connected together, and said motor; and

cross-terminal voltage sensors that detect the cross-terminal voltage of the main switching elements in the each of the circuits for each phase;

said resonant circuit comprises auxiliary connection points in which three auxiliary circuits, one for each phase, connected serially to two auxiliary switching elements that allow a current to pass only in one direction are connected in parallel, and two auxiliary switching elements in each of the auxiliary circuits for each phase are connected together;

three phase auxiliary circuits connected to the main connection points of said inverter circuit;

resonant inductors connected between the auxiliary connection points in said auxiliary circuits for each phase and said terminals on the opposite side; and

a resonant current sensor that detects a resonant current flowing to the inductor;

said control circuit comprises a zero voltage detecting device that detects whether or not the cross-terminal voltage detected by each of the cross-terminal voltage sensors is zero and outputs a zero voltage detection signals that corresponds to each of the cross-terminal voltages in the case that they are zero;

a resonant current arrival determining device that determines whether or not the resonant current detected by said resonant current sensors is larger than the load current detected by said load current sensors and in the case that they are larger outputs an arrival determination signal;

a drive signal generating device that generates a main drive signal that turns OFF the main switching elements to a non-conducting state when the resonant current arrival determination device has output an arrival determination signal, generates a main drive signal that turns ON the main switching elements to a conducting state when said zero voltage detecting device has output a zero voltage detection signal corresponding to each cross-terminal voltage, generates an auxiliary drive signal that turn ON the auxiliary switching elements at a predefined switching timing, and turns OFF an auxiliary switching element that is in a conducting state after a predetermined on continuation time has passed from the predefined switching timing; and

current conducting device determining devices that determine whether or not a current is flowing in any of the main switching elements or diodes in each of the circuits for each phase in said inverter circuit; and

said drive signal generating device comprises a resonant action prohibiting device that prohibits the generation of an auxiliary drive signal that turns ON a corresponding auxiliary switching element in said resonant circuit during the turn-OFF of the main switching element in the case that said current conducting device determination device has determined that a current is flowing in a main switching element.

7. A resonant inverter apparatus according to claim 6 wherein said current conducting device determining device comprises a current conduction direction determining device that determines the direction that a load current detected by said load current sensor is flowing;

and a logic processing device that determines whether or not a current is flowing in any of the main switching elements or diodes in each main circuit for each phase in the inverter circuit based on the direction in which the load current determined by this current conduction direction determining means is flowing and the main drive signal generated by said drive signal generating device.