Three-phase current sensor and estimator
First Claim
1. A leg current estimator combination for estimating the load current in each of the legs A, B and C of a three-phase load, each leg being driven by a controlled power driver such as a pulse-width modulated field-effect transistor (FET) pair or insulated gate bipolar transistor (IGBT) pair, comprising:
- a) a low-resistance leg resistor in each leg of the load and means for deriving the voltage across each said resistor;
b) a first differential amplifier receiving as its two inputs the voltage across the resistors for legs A and C of the load and producing a first analog output signal representing the difference between the two inputs thereto;
c) a second differential amplifier receiving as its two inputs the voltage across the resistors for legs B and C of the load and producing a second analog output signal representing the difference between the two inputs thereto;
d) a first analog/digital converter for converting the output of the first differential amplifier to a digital signal;
e) a second analog/digital converter for converting the output of the second differential amplifier to a digital signal;
f) a leg A output circuit comprising in series a leg A output combiner receiving as a first input the output of the first analog/digital converter, a leg A integrator for integrating the output of the leg A combiner, and a leg A output amplifier for providing an output signal representing the estimated leg A load current;
g) a leg C output circuit comprising in series a leg C output combiner receiving as a first input the output of the second analog/digital converter, a leg C integrator for integrating the output of the leg C combiner, and a leg C output amplifier for providing an output signal representing the estimated leg C load current;
h) an intermediate combiner receiving as a first input the output of the first analog/digital converter and receiving as a second input the output of the second analog/digital converter and producing an intermediate output signal representing the difference between the two input signals thereto;
i) a leg B output circuit comprising in series a leg B output combiner receiving as a first input the intermediate output signal, a leg B integrator for integrating the output of the combiner, and a leg B output amplifier for providing an output signal representing the estimated leg B load current;
j) a leg A feedback loop comprising a leg A multiplier and a leg A feedback combiner connected in series, the leg A multiplier receiving as a first input the output of the leg A output amplifier and as a second input a signal representing the value (M−
α
)/M, and producing a multiplier output signal representing the product of the values of the first and second inputs to the leg A multiplier, said multiplier output signal being fed as a first input to the leg A feedback combiner;
k) a leg B feedback loop comprising a leg B multiplier and a leg B feedback combiner connected in series, the leg B multiplier receiving as a first input the output of the leg B output amplifier and as a second input a signal representing the value (M−
β
)/M, and producing a multiplier output signal representing the product of the values of the first and second inputs to the leg B multiplier, said multiplier output signal being fed as a first input to the leg B feedback combiner;
l) a leg C feedback loop comprising a leg C multiplier and a leg C feedback combiner connected in series, the leg C multiplier receiving as a first input the output of the leg C output amplifier and as a second input a signal representing the value (M−
γ
)/M, and producing a multiplier output signal representing the product of the values of the first and second inputs to the leg C multiplier, said multiplier output signal being fed as a first input to the leg C feedback combiner;
the leg A feedback combiner receiving as a second input the output of the leg C multiplier, and producing an output signal representing the difference between the two inputs thereto;
the leg B feedback combiner receiving as a second input the output of the leg A multiplier, and producing an output signal representing the difference between the two inputs thereto;
the leg C feedback combiner receiving as a second input the output of the leg B multiplier, and producing an output signal representing the difference between the two inputs thereto;
the leg A output combiner receiving as a second input the output of the leg A feedback combiner with optional amplification and producing as the leg A output combiner signal the difference between the two inputs thereto;
the leg B output combiner receiving as a second input the output of the leg B feedback combiner with optional amplification and producing as the leg B output combiner signal the difference between the two inputs thereto;
the leg C output combiner receiving as a second input the output of the leg C feedback combiner with optional amplification and producing as the leg C output combiner signal the negative of the sum of the two inputs thereto;
wherein each of the leg A, leg B and leg C combiners produces a respective output signal value uA, uB, or uC (each value generically referred to as “
u”
);
each of the integrators processes its associated input signal value u to produce an output signal value where s is the Laplace operator;
each of the leg A, leg B and leg C output amplifiers has a gain z;
M is the half-period of the pulse-width modulation carrier signal;
and the values α
, β and
γ
are derived from the equations
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Accused Products
Abstract
In a three-phase DC-to-AC inverter including, for driving each leg of the load, a controlled power driver such a pulse-width modulated field-effect transistor (FET) or insulated gate bipolar transistor (IGBT) pair, an estimator for estimating the current in each leg of the load. A low-resistance leg resistor is connected in series in the lower leg of each transistor pair. The voltages across the leg resistors are applied to two differential amplifiers to generate two discrete voltage difference values that are transmitted to an estimator. The estimator solves specified differential equations using suitably interconnected combiners, integrators, amplifiers and multipliers, or discrete digital equivalent or programmed computer equivalent, to derive a value for the estimated current in each leg of the load.
48 Citations
27 Claims
-
1. A leg current estimator combination for estimating the load current in each of the legs A, B and C of a three-phase load, each leg being driven by a controlled power driver such as a pulse-width modulated field-effect transistor (FET) pair or insulated gate bipolar transistor (IGBT) pair, comprising:
-
a) a low-resistance leg resistor in each leg of the load and means for deriving the voltage across each said resistor;
b) a first differential amplifier receiving as its two inputs the voltage across the resistors for legs A and C of the load and producing a first analog output signal representing the difference between the two inputs thereto;
c) a second differential amplifier receiving as its two inputs the voltage across the resistors for legs B and C of the load and producing a second analog output signal representing the difference between the two inputs thereto;
d) a first analog/digital converter for converting the output of the first differential amplifier to a digital signal;
e) a second analog/digital converter for converting the output of the second differential amplifier to a digital signal;
f) a leg A output circuit comprising in series a leg A output combiner receiving as a first input the output of the first analog/digital converter, a leg A integrator for integrating the output of the leg A combiner, and a leg A output amplifier for providing an output signal representing the estimated leg A load current;
g) a leg C output circuit comprising in series a leg C output combiner receiving as a first input the output of the second analog/digital converter, a leg C integrator for integrating the output of the leg C combiner, and a leg C output amplifier for providing an output signal representing the estimated leg C load current;
h) an intermediate combiner receiving as a first input the output of the first analog/digital converter and receiving as a second input the output of the second analog/digital converter and producing an intermediate output signal representing the difference between the two input signals thereto;
i) a leg B output circuit comprising in series a leg B output combiner receiving as a first input the intermediate output signal, a leg B integrator for integrating the output of the combiner, and a leg B output amplifier for providing an output signal representing the estimated leg B load current;
j) a leg A feedback loop comprising a leg A multiplier and a leg A feedback combiner connected in series, the leg A multiplier receiving as a first input the output of the leg A output amplifier and as a second input a signal representing the value (M−
α
)/M, and producing a multiplier output signal representing the product of the values of the first and second inputs to the leg A multiplier, said multiplier output signal being fed as a first input to the leg A feedback combiner;
k) a leg B feedback loop comprising a leg B multiplier and a leg B feedback combiner connected in series, the leg B multiplier receiving as a first input the output of the leg B output amplifier and as a second input a signal representing the value (M−
β
)/M, and producing a multiplier output signal representing the product of the values of the first and second inputs to the leg B multiplier, said multiplier output signal being fed as a first input to the leg B feedback combiner;
l) a leg C feedback loop comprising a leg C multiplier and a leg C feedback combiner connected in series, the leg C multiplier receiving as a first input the output of the leg C output amplifier and as a second input a signal representing the value (M−
γ
)/M, and producing a multiplier output signal representing the product of the values of the first and second inputs to the leg C multiplier, said multiplier output signal being fed as a first input to the leg C feedback combiner;
the leg A feedback combiner receiving as a second input the output of the leg C multiplier, and producing an output signal representing the difference between the two inputs thereto;
the leg B feedback combiner receiving as a second input the output of the leg A multiplier, and producing an output signal representing the difference between the two inputs thereto;
the leg C feedback combiner receiving as a second input the output of the leg B multiplier, and producing an output signal representing the difference between the two inputs thereto;
the leg A output combiner receiving as a second input the output of the leg A feedback combiner with optional amplification and producing as the leg A output combiner signal the difference between the two inputs thereto;
the leg B output combiner receiving as a second input the output of the leg B feedback combiner with optional amplification and producing as the leg B output combiner signal the difference between the two inputs thereto;
the leg C output combiner receiving as a second input the output of the leg C feedback combiner with optional amplification and producing as the leg C output combiner signal the negative of the sum of the two inputs thereto;
wherein each of the leg A, leg B and leg C combiners produces a respective output signal value uA, uB, or uC (each value generically referred to as “
u”
);
each of the integrators processes its associated input signal value u to produce an output signal value where s is the Laplace operator; each of the leg A, leg B and leg C output amplifiers has a gain z;
M is the half-period of the pulse-width modulation carrier signal;
and the values α
, β and
γ
are derived from the equations - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
-
-
14. An estimator combination for estimating the load current in each of the legs A, B and C of a three-phase load, each leg being driven by a controlled power driver, comprising:
-
a) a low-resistance leg resistor in each leg of the load and means for deriving the voltage across each said resistor;
b) first differential means for producing a first differential digital signal representing the voltage difference between the voltages across the low-resistance leg resistors of legs A and C of the load;
c) second differential means for producing a second differential digital signal representing the voltage difference between the voltages across the low-resistance leg resistors of legs B and C of the load;
d) a leg A output circuit comprising in series a leg A output combiner receiving as a first input the first differential digital signal, a leg A integrator for integrating the output of the leg A combiner, and a leg A output amplifier for providing an output signal representing the estimated leg A load current;
e) a leg C output circuit comprising in series a leg C output combiner receiving as a first input the second differential digital signal, a leg C integrator for integrating the output of the leg C combiner, and a leg C output amplifier for providing an output signal representing the estimated leg C load current;
f) an intermediate combiner receiving as a first input the first differential digital signal and receiving as a second input the second differential digital signal and producing an intermediate output signal representing the difference between the two input signals thereto;
g) a leg B output circuit comprising in series a leg B output combiner receiving as a first input the intermediate output signal, a leg B integrator for integrating the output of the combiner, and a leg B output amplifier for providing an output signal representing the estimated leg B load current;
h) a leg A feedback loop comprising a leg A multiplier and a leg A feedback combiner connected in series, the leg A multiplier receiving as a first input the output of the leg A output amplifier and as a second input a signal representing the value (M−
α
)/M, and producing a multiplier output signal representing the product of the values of the first and second inputs to the leg A multiplier, said multiplier output signal being fed as a first input to the leg A feedback combiner;
i) a leg B feedback loop comprising a leg B multiplier and a leg B feedback combiner connected in series, the leg B multiplier receiving as a first input the output of the leg B output amplifier and as a second input a signal representing the value (M−
β
)/M, and producing a multiplier output signal representing the product of the values of the first and second inputs to the leg B multiplier, said multiplier output signal being fed as a first input to the leg B feedback combiner;
j) a leg C feedback loop comprising a leg C multiplier and a leg C feedback combiner connected in series, the leg C multiplier receiving as a first input the output of the leg C output amplifier and as a second input a signal representing the value (M−
γ
)/M, and producing a multiplier output signal representing the product of the values of the first and second inputs to the leg C multiplier, said multiplier output signal being fed as a first input to the leg C feedback combiner;
the leg A feedback combiner receiving as a second input the output of the leg C multiplier, and producing an output signal representing the difference between the two inputs thereto;
the leg B feedback combiner receiving as a second input the output of the leg A multiplier, and producing an output signal representing the difference between the two inputs thereto;
the leg C feedback combiner receiving as a second input the output of the leg B multiplier, and producing an output signal representing the difference between the two inputs thereto;
the leg A output combiner receiving as a second input the output of the leg A feedback combiner with optional amplification and producing as the leg A output combiner signal the difference between the two inputs thereto;
the leg B output combiner receiving as a second input the output of the leg B feedback combiner with optional amplification and producing as the leg B output combiner signal the difference between the two inputs thereto;
the leg C output combiner receiving as a second input the output of the leg C feedback combiner with optional amplification and producing as the leg C output combiner signal the negative of the sum of the two inputs thereto;
wherein each of the leg A, leg B and leg C combiners produces a respective output signal value uA, uB or uC (each value generically referred to as “
u”
);
each of the integrators processes its associated input signal value u to produce an output signal valuewhere s is the Laplace operator;
each of the leg A, leg B and leg C output amplifiers has a gain z;
M is the half-period of the pulse-width modulation carrier signal; and
the values α
, β and
γ
are derived from the equations - View Dependent Claims (15)
-
-
16. A three-phase DC-to-AC inverter, including three pairs of FET transistors and control means to pulse-width modulate said transistors, comprising:
-
(a) an estimator combination for deriving the estimated current in each of the legs A, B and C of the load, said estimator comprising;
(i) first, second and third low-resistance leg resistors in respective return legs of each pair of transistors;
(ii) first and second differential amplifiers;
(iii) means to apply the voltage appearing at the junction of the return leg of the first pair of transistors and the associated first resistor to a first terminal of said first differential amplifier;
(iv) means to apply the voltage appearing at the junction of the return leg of the third pair of transistors and the associated third resistor to a second terminal of said first differential amplifier;
(v) means to apply the voltage appearing at the junction of the return leg of the second pair of transistors and the associated second resistor to a first terminal of said second differential amplifier; and
(vi) means to apply the voltage appearing at the junction of the return leg of the third pair of transistors and the associated third resistor to a second terminal of said second differential amplifier; and
(b) a signal processor to process the output signal Dvac of the first differential amplifier and the output signal Dvbc of the second differential amplifier;
where the output signal Dvac of the first differential amplifier is - View Dependent Claims (17, 18)
-
-
19. An estimator combination for estimating the load current in each of the legs A, B and C of a three-phase load, each leg being driven by a controlled power driver such as a pulse-width modulated field-effect transistor (FET) pair or insulated gate bipolar transistor (IGBT) pair, comprising:
-
a) a low-resistance leg resistor in each leg of the load and means for deriving the voltage across each said resistor;
b) a first differential amplifier receiving as its two inputs the voltage across the resistors for legs A and C of the load and producing an analog output signal representing the difference between the two inputs thereto;
c) a second differential amplifier receiving as its two inputs the voltage across the resistors for legs B and C of the load and producing an analog output signal representing the difference between the two inputs thereto;
d) a first analog/digital converter for converting the output of the first differential amplifier to a digital signal;
e) a second analog/digital converter for converting the output of the second differential amplifier to a digital signal;
f) a leg A output circuit comprising in series a leg A output combiner receiving as a first input the output of the first analog/digital converter, a leg A integrator for integrating the output of the leg A combiner, and a leg A output amplifier for providing an output signal representing the estimated leg A load current;
g) a leg C output circuit comprising in series a leg C output combiner receiving as a first input the output of the second analog/digital converter, a leg C integrator for integrating the output of the leg C combiner, and a leg C output amplifier for providing an output signal representing the estimated leg C load current;
h) an intermediate combiner receiving as a first input the output of the first analog/digital converter and receiving as a second input the output of the second analog/digital converter and producing an intermediate output signal representing the difference between the two input signals thereto;
i) a leg B output circuit comprising in series a leg B output combiner receiving as a first input the intermediate output signal, a leg B integrator for integrating the output of the combiner, and a leg B output amplifier for providing an output signal representing the estimated leg B load current;
j) a leg A feedback loop comprising a leg A multiplier and a leg A feedback combiner connected in series, the leg A multiplier receiving as a first input the output of the leg A output amplifier and as a second input a signal representing the value (M−
α
)/M, and producing a multiplier output signal representing the product of the values of the first and second inputs to the leg A multiplier, said multiplier output signal being fed as a first input to the leg A feedback combiner;
k) a leg B feedback loop comprising a leg B multiplier and a leg B feedback combiner connected in series, the leg B multiplier receiving as a first input the output of the leg B output amplifier and as a second input a signal representing the value (M−
β
)/M, and producing a multiplier output signal representing the product of the values of the first and second inputs to the leg B multiplier, said multiplier output signal being fed as a first input to the leg B feedback combiner;
l) a leg C feedback loop comprising a leg C multiplier and a leg C feedback combiner connected in series, the leg C multiplier receiving as a first input the output of the leg C output amplifier and as a second input a signal representing the value (M−
γ
)/M, and producing a multiplier output signal representing the product of the values of the first and second inputs to the leg C multiplier, said multiplier output signal being fed as a first input to the leg C feedback combiner;
the leg A feedback combiner receiving as a second input the output of the leg C multiplier, and producing an output signal representing the difference between the two inputs thereto;
the leg B feedback combiner receiving as a second input the output of the leg A multiplier, and producing an output signal representing the difference between the two inputs thereto;
the leg C feedback combiner receiving as a second input the output of the leg B multiplier, and producing an output signal representing the difference between the two inputs thereto;
the leg A output combiner receiving as a second input the output of the leg A feedback combiner with optional amplification and producing as the leg A output combiner signal the difference between the two inputs thereto;
the leg B output combiner receiving as a second input the output of the leg B feedback combiner with optional amplification and producing as the leg B output combiner signal the difference between the two inputs thereto;
the leg C output combiner receiving as a second input the output of the leg C feedback combiner with optional amplification and producing as the leg C output combiner signal the negative of the sum of the two inputs thereto;
wherein each of the leg A, leg B and leg C combiners produces a respective output signal value uA, uB or uC (each value generically referred to as “
u”
);
each of the integrators processes its associated input signal value u to produce an output signal value
where s is the Laplace operator;
each of the leg A, leg B and leg C output amplifiers has a gain z;
M is the half-period of the pulse-width modulation carrier signal; and
the values α
, β and
γ
are derived from the equations - View Dependent Claims (20, 21, 22)
-
-
23. A combination for estimating the load current in each of three legs A, B, C of a three-phase load, each said leg being driven by a controlled power driver such as a pulse-width modulated field-effect transistor (FET) pair or insulated gate bipolar transistor (IGBT) pair, in response to pulse-width modulation provided by a microcontroller connected to the controlled power drivers;
- wherein the microcontroller produces selected parameter signals representing the values of parameters α
, β
, γ
, M and z of the inverter;
comprising;a) a low-resistance leg resistor in each leg of the load and means for deriving the voltage across each said resistor;
b) first differential means for producing a first differential digital signal representing the voltage difference between the voltages across the low-resistance leg resistors of legs A and C of the load;
c) second differential means for producing a second differential digital signal representing the voltage difference between the voltages across the low-resistance leg resistors of legs B and C of the load;
d) a signal processor for receiving the first and second differential digital signals and the selected parameter signals and processing said signals to derive an estimated current for each leg of the load;
where the value M is the half-period of the pulse-width modulation carrier signal; and
the values α
, β and
γ
are derived from the equations
α
=VL sin(ω
t−
Φ
) - View Dependent Claims (24)
- wherein the microcontroller produces selected parameter signals representing the values of parameters α
-
25. A combination for estimating the load current in each of three legs A, B, C of a three-phase load, each leg being driven by a controlled power driver such as a pulse-width modulated field-effect transistor (FET) pair or insulated gate bipolar transistor (IGBT) pair in response to pulse-width modulation provided by a microcontroller connected to the controlled power drivers;
- wherein the microcontroller produces selected parameter signals representing the values of parameters α
, β
, γ
, M and z of the inverter;
comprising;a) a low-resistance leg resistor in each leg of the load and means for deriving the voltage across each said resistor; and
b) a signal processor receiving (i) signals derived from the voltages across the low-resistance leg resistors and (ii) the selected parameter signals, and processing said signals to derive an estimated current for each leg of the load;
where the value M is the half-period of the pulse-width modulation carrier signal; and
the values α
, β and
γ
are derived from the equations - View Dependent Claims (26, 27)
- wherein the microcontroller produces selected parameter signals representing the values of parameters α
Specification