Bidirectional power converter modules, and power system using paralleled modules
First Claim
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1. A bidirectional paralleled power converter apparatus for coupling between a first source of direct electrical energy and a second source of electrical energy, the voltage of said first source of direct electrical energy being less than the voltage of said second source of direct electrical energy, said converter comprising:
- a source of power converter apparatus reference voltage;
power converter apparatus error signal generating means including an output port, and also including a first input port coupled to said source of power converter apparatus reference voltage and also including a second input port coupled to receive a sample of power converter apparatus feedback voltage, for generating, at said output port of said power converter apparatus error signal generating means, a power converter apparatus error signal representative of voltage error;
at least one bidirectional switching power converter, said bidirectional switching power converter including a first power port coupled to said first source of direct electrical energy, and a second power port coupled to said second source of direct electrical energy, said bidirectional switching power converter further including a feedback signal input port coupled to said output port of said power converter apparatus error signal generating means, said bidirectional switching power converter further comprising;
(a) inductance means including first and second terminals;
(b) power coupling means coupled to said first and second power ports and to said first and second terminals of said inductance means, for, in a first (boost) mode of operation, periodically coupling said inductance means alternately (i) across said first power port and (ii) between said first and said second power ports, for transferring energy from said first source of direct electrical energy to said second source of direct electrical energy, and for, in a second (buck) mode of operation, periodically coupling said inductance means (i) between said first (1) and said second power port and (ii) across said first power port, for transferring energy from said second source of direct electrical energy to said first source of direct electrical energy, and for changing between said first and second modes of operation under the control of the duty cycle of a switching control signal;
(c) resistance-type current sensing means serially coupled with said inductance means, for generating a current representative voltage representative of the current flowing in said inductance means;
(d) control means including a first input port, and an output port, said output port of said control means being coupled to said power coupling means, and responsive to the sum of currents applied to said first input port of said control means, for generating said switching control signal for said power coupling means;
(e) second coupling means coupled to said first input port of said control means and to said feedback signal input port of said bidirectional switching power converter, for converting said power converter apparatus error signal into a power converter apparatus control current, and for coupling said power converter apparatus control current to said first input port of said control means;
(f) third coupling means coupled to said resistance-type current sensing means and to said first input port of said control means, for converting said current representative voltage representative of the current flowing in said inductance means into an inductance-current representative current, and for coupling said inductance-current representative current to said first input port of said control means;
whereby switching noise associated with said current-representative voltage representative of the current flowing in said inductance means tends to destabilize said bidirectional switching power converter;
said bidirectional switching power converter further comprising;
(g) low-pass filtering means coupled to said resistance-type current sensing means, for low-pass filtering said current representative voltage representative of the current flowing in said inductance means, to thereby produce a signal representative of the low frequency components of the current in said inductance means, and for applying said signal representative of the low-frequency components of the current in said inductance means to said first input port of said control means;
which thereby stabilizes said bidirectional switching power converter, but tends to destabilize said paralleled power converter apparatus, because the bandwidth of said inductance-current representative current is less than the bandwidth of said power converter apparatus error signal;
said bidirectional switching power converter further comprising;
(h) transformer-type current sensing means magnetically coupled to said inductance means, and coupled to said first input port of said control means, for generating a high frequency inductor signal current representative of the high-frequency components of current flowing in said inductance means, and for coupling said high-frequency inductor signal current to said first input port of said control means;
whereby signals representative of both said low-frequency components and said high-frequency components of said current in said inductance means are applied to said first port of said control means, the bandwidth of said bidirectional switching power converter is increased, and said paralleled power converter apparatus is thereby stabilized.
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Abstract
A bidirectional power converter array has overall voltage feedback, an error signal generator, and plural bidirectional power converter modules. Each module of the array includes a series inductor and local feedback based upon the inductor current. Each module also has a resistive current sensor, providing wideband local feedback. A low-pass filter is coupled to the current sensing resistor to reduce switching noise. The low-pass filter also reduces the bandwidth of the local feedback signal, so interactions with the overall feedback occur, which may result in instability. A winding transformer-coupled to the series inductor generates AC signal representing high-frequency components of the inductor current, relatively free of switching noise. The AC current sample is added to the low-frequency components derived from the resistor and low-pass filter, to form a low-noise local feedback signal, with sufficient bandwidth to reduce unwanted interactions with the overall system feedback. The feedback signals may be currents summed at a node. The combination of overall voltage feedback which is converted to local current feedback in each module allows modules to be paralleled without any adjustments to the system or to the individual modules.
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3 Claims
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1. A bidirectional paralleled power converter apparatus for coupling between a first source of direct electrical energy and a second source of electrical energy, the voltage of said first source of direct electrical energy being less than the voltage of said second source of direct electrical energy, said converter comprising:
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a source of power converter apparatus reference voltage; power converter apparatus error signal generating means including an output port, and also including a first input port coupled to said source of power converter apparatus reference voltage and also including a second input port coupled to receive a sample of power converter apparatus feedback voltage, for generating, at said output port of said power converter apparatus error signal generating means, a power converter apparatus error signal representative of voltage error; at least one bidirectional switching power converter, said bidirectional switching power converter including a first power port coupled to said first source of direct electrical energy, and a second power port coupled to said second source of direct electrical energy, said bidirectional switching power converter further including a feedback signal input port coupled to said output port of said power converter apparatus error signal generating means, said bidirectional switching power converter further comprising; (a) inductance means including first and second terminals; (b) power coupling means coupled to said first and second power ports and to said first and second terminals of said inductance means, for, in a first (boost) mode of operation, periodically coupling said inductance means alternately (i) across said first power port and (ii) between said first and said second power ports, for transferring energy from said first source of direct electrical energy to said second source of direct electrical energy, and for, in a second (buck) mode of operation, periodically coupling said inductance means (i) between said first (1) and said second power port and (ii) across said first power port, for transferring energy from said second source of direct electrical energy to said first source of direct electrical energy, and for changing between said first and second modes of operation under the control of the duty cycle of a switching control signal; (c) resistance-type current sensing means serially coupled with said inductance means, for generating a current representative voltage representative of the current flowing in said inductance means; (d) control means including a first input port, and an output port, said output port of said control means being coupled to said power coupling means, and responsive to the sum of currents applied to said first input port of said control means, for generating said switching control signal for said power coupling means; (e) second coupling means coupled to said first input port of said control means and to said feedback signal input port of said bidirectional switching power converter, for converting said power converter apparatus error signal into a power converter apparatus control current, and for coupling said power converter apparatus control current to said first input port of said control means; (f) third coupling means coupled to said resistance-type current sensing means and to said first input port of said control means, for converting said current representative voltage representative of the current flowing in said inductance means into an inductance-current representative current, and for coupling said inductance-current representative current to said first input port of said control means; whereby switching noise associated with said current-representative voltage representative of the current flowing in said inductance means tends to destabilize said bidirectional switching power converter;
said bidirectional switching power converter further comprising;(g) low-pass filtering means coupled to said resistance-type current sensing means, for low-pass filtering said current representative voltage representative of the current flowing in said inductance means, to thereby produce a signal representative of the low frequency components of the current in said inductance means, and for applying said signal representative of the low-frequency components of the current in said inductance means to said first input port of said control means; which thereby stabilizes said bidirectional switching power converter, but tends to destabilize said paralleled power converter apparatus, because the bandwidth of said inductance-current representative current is less than the bandwidth of said power converter apparatus error signal;
said bidirectional switching power converter further comprising;(h) transformer-type current sensing means magnetically coupled to said inductance means, and coupled to said first input port of said control means, for generating a high frequency inductor signal current representative of the high-frequency components of current flowing in said inductance means, and for coupling said high-frequency inductor signal current to said first input port of said control means; whereby signals representative of both said low-frequency components and said high-frequency components of said current in said inductance means are applied to said first port of said control means, the bandwidth of said bidirectional switching power converter is increased, and said paralleled power converter apparatus is thereby stabilized. - View Dependent Claims (2, 3)
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Current AssigneeLockheed Martin Corporation (Martin Marietta Corporation)
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Original AssigneeMartin Marietta Corporation
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InventorsLinkowsky, Frank A., Bingley, John D.
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Primary Examiner(s)Wong, Peter S.
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Assistant Examiner(s)HAN, YOUNGHUIE JESSICA
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Application NumberUS08/505,939Time in Patent Office568 DaysField of Search323/222, 323/224, 323/271, 323/272, 323/282, 323/284, 323/285, 323/906, 307/43US Class Current323/272CPC Class CodesG05F 3/22 wherein the transistors are...H02M 3/1582 Buck-boost converters H02M3...
