Resonant inverter control system
First Claim
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.
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Accused Products
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.
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Citations
7 Claims
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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. - View Dependent Claims (2, 3, 4, 5)
- 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;
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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:
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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. - View Dependent Claims (7)
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Specification